Posted by Lyle in: Battery, Engineering, Generator, Original GM-Volt Interviews, Performance with 226 Comments
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The way the Volt is designed, the first 40 miles of driving are powered by the electric energy stored in the battery. After that distance from full charge, somewhere around 30% state of charge, the on-board generator kicks in. The generator’s job is to keep the battery at that 30% level all the way until the driver can get to where he or she will begin charging again. That level is called the “customer depletion point”. Below is Volt chief engineer Andrew Farah explaining how the Volt will behave at and beyond that level.
How will the vehicle’s propulsion system work when you get to the customer depletion point?
When you get to the customer depletion point, the engine will come on seamlessly as it’s supposed to. But when the engine comes on to spin the generator, it does so with the idea that we’re generating electric energy to drive the wheels, not to charge the battery. People say the engine comes on to charge the battery, but that’s not what really goes on. The engine comes on to make enough electric energy to turn the wheels, because the wheels are always turning electrically.
Now comes the fun part. Remember the electric generator is about half the size of the motor. So you say, how come you don’t have performance problems if you’re trying to go up a hill with only basically half the power capability? That’s where the battery comes back into play. Because the customer depletion point is not full depletion, there’s still energy available. That’s by design. The idea is during certain other peak situations such as climbing a hill or merging into traffic, you will actually take some more energy out of the battery. So you may actually come down a little bit below customer depletion level.
And then when you take your foot off the gas, as an example when you’re done doing the merge, we had taken a little bit out and the battery has a little less in it. So what we’ll do then is we will opportunistically put that energy back into the battery either through regenerative braking or if we have to we will take some of the energy that’s not needed to turn the wheels and bring the battery up to the customer depletion level.
So we don’t recharge the battery. The customer wont actually see any of this, as their electric range indicator in the car will only say zero.
We are actually using that battery at that point as a peak buffer and we will keep trying to recapture energy as the opportunities allow.
Is the customer depletion point going to be exactly 30% state of charge (SOC)?
We are continuing to tweak and tune and develop exactly what that number is.
Aug 25th, 2008 (5:59 am)Cool. So we can deplete the battery slightly below 30% SOC and the car will bring it back up to 30% SOC. I’m curious. What was the reason why they can’t charge the battery up to 80% SOC with the ICE? I honestly can’t remember the reason.
Aug 25th, 2008 (6:22 am)Rashid -
You don’t want to use the ICE to recharge the battery up to 80% SOC, because that defeats the purpose of a plug-in hybrid: which is to replace the burning of gasoline with electricity as much as possible.
Aug 25th, 2008 (6:23 am)Very sophisticated, although it defies a neat summary in today’s “sound-bite” world. They would do themselves a favor by staying away from phrases like “customer depletion point.” But that’s an engineer for you. They need to use language the layman will understand.
But it validates my gut feeling that GM is thinking this vehicle through very carefully.
Oh, and kudos to Lyle for getting this on the record.
Aug 25th, 2008 (6:23 am)Customer Depletion Point ?
Who in the hell came up with that Techno Babble phrase ?
Aug 25th, 2008 (6:25 am)Rashiid:
I don’t think it is that it can’t be done, it is a decision “NOT” to do it.
Because obviously if you use some of the battery power as a buffer for the generator, and then later the generator or re-gen braking brings the battery back up to 30%, it is recharging the battery.
But the question is: If they have “energy that is not needed to turn the wheels” available, but do not want to charge the battery with it, what are they doing with it? Or will they just shut down the ICE at that point?
Like I said before, it gets complicated…..
Aug 25th, 2008 (6:27 am)Rashiid, the reason is simple: that would be economically impractical.
Aug 25th, 2008 (6:28 am)I wonder what happens if you deplete the battery to 30% and then start up a large mountain chain with 4 heavy passengers and a clamshell full of luggage on the roof? The battery would be called on for extra power but the regen braking would not make it up.
This is an extreme case but is one that the reviewers will look into when the car arrives.
I would assume that you ultimately loose power down to the ICE/Gen output capacity and then you would be limited in power?
Aug 25th, 2008 (6:36 am)#1 Amul
To bring the battery back to 80% SOC would use more gasoline. Also when arriving at your charging station you want your battery in a depleted state to take full advantage of propeling your Volt by means of on-grid electrical energy or alternative electrical energy.
Aug 25th, 2008 (6:48 am)Jim @ 5,
But the question is: If they have “energy that is not needed to turn the wheels” available, but do not want to charge the battery with it, what are they doing with it? Or will they just shut down the ICE at that point?
I’ve been wondering about that too. Maybe the ICE will turn at variable RPMs so that only the necessary amount of energy to propel the car and run whatever accessories happen to be turned on is generated. That’s essentially how a normal ICE vehicle works. Regardless of where the battery SOC is, I think that you would always want to recapture energy from the regenerative braking, as that is as close to “free” energy as you are going to get.
Aug 25th, 2008 (6:49 am)Lyle,
Great article. This really addresses the heart of how it works.
I wonder if Andrew Farah could tell us more about how the engine behaves. Is it constant RPM or variable RPM? Does the gas engine turn off at low speeds? Will the engine ever turn on above the customer depletion point in order to prevent stale gas and/or make sure the engine still runs?
Aug 25th, 2008 (6:53 am)#9 MDDave Says: “Maybe the ICE will turn at variable RPMs so that only the necessary amount of energy to propel the car and run whatever accessories happen to be turned on is generated. Regardless of where the battery SOC is, I think that you would always want to recapture energy from the regenerative braking, as that is as close to “free” energy as you are going to get.”
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With either constant or variable RPM engine designs, the gas engine output can be varied to accommodate a varying load. With a constant RPM engine, the fuel mixture is varied.
When regenerative braking occurs, the engine output will be reduced dramatically, or perhaps the engine will even be shut off.
Aug 25th, 2008 (6:54 am)7 Nuclearboy:
There is actually a perfect testing scenario for that. I-40 from Tennessee heading to Asheville.
24 miles of switchbacks and inclines. from West-East Tenn-Asheville there are no declines. It is all uphill.
This is also the area that BMW uses to test their cars handling for the states and I think they also used it to test the Corvette.
Aug 25th, 2008 (6:57 am)#5 jim, I was thinking the same thing as you.
Does the engine actually shut off if you are in ICE mode? Let’s assume you just went up a big hill in ICE mode and are down to %25 now you are sitting in the parking lot with the AC on. After reading the article I get the impression that the ice will run the AC and charge the battery up to %30. Now, at %30 you still have the AC on, so does the ICE
A. Stay on to keep the AC going and continue to charge the battery with the remaining power. And if so to what percent will it do this?
B. Stay on to keep the AC going but waste the extra electricity.
C. turn off and let the battery power the AC for some time down to say %25 and then the ICE will kick back on
D. Turn off and let the battery run the AC untill the battery is dead.
Personally I think there needs to be a range say %25 to %35 that when the battery gets below %25 the ICE will stay on and power the car and charge the batt until it gets up to %35. At %35 you are back to straight battery. A range like that won’t have your engine charging the battery needlessly and won’t be wasting electricity. The article just seemed a little ambiguous and clarification would be helpful.
Aug 25th, 2008 (7:02 am)About the variable RPM stuff, I thought we were told that the engine would be constantly running at it’s peak operating RPM constantly. Maybe I got that wrong but that was the impression I got. After reading this article it seems to me that the peak RPM efficiency is probably matched up with the maximum generating capacity of the generator. If that is the case, more RPM’s wouldn’t translate into more energy for the battery. But that also means if only a little energy is needed, you are either charging the battery too or wasting the extra energy.
Hey Lyle, thanks for the monday morning mental stimulation!
Aug 25th, 2008 (7:09 am)This is about how I thought it would work.
Nuclearboy #7 – I brought this up some months ago but added headlights, wipers and HVAC to the equation. I guess there will be a point at which these factors could affect performance just as they do in an ICE powered vehicle. I once owned one of those small motor homes on a Toyota chassis. Had a 4 cylinder engine which was adequate about 90% of the time. But if you were in the mountains or had a head wind then there were issues.
Aug 25th, 2008 (7:12 am)The 80% limit (and 20% low limit) is there because lithium batteries are damaged slightly when they’re either fully charged or fully depleted.
The limits aren’t economical or environmental, it’s to extend the life of the battery.
Aug 25th, 2008 (7:13 am)I find Farah’s explanation very confusing.
I also have to wonder what happens to the car if you run into a situation where your power demand is large and sustained for a long period of time. It takes a lot of juice to climb the Rockies… what happens if you leave Denver after driving around for 40 miles and depleting the battery, then head into the hills? Climbing takes a lot of power. Will a 1.4L engine provide enough electricity to keep the battery from becoming severely depleted?
Aug 25th, 2008 (7:22 am)I don’t care what they call it for now…..as long it works. The Volt is only in the building stage and by the time the car gets in the customers hand, the wording in the manual will have been carefully scrutinized.
Aug 25th, 2008 (7:24 am)Oh my heart be still…. the posted pic is an EV1 dash!
It’s cool to see the power up sequence.
http://www.youtube.com/watch?v=bsdUfAEIEos
To the point… I’m glad they finally cleared up the phrase “charge the battery”, very misleading, confusing etc…
The engine may very well always run at a constant speed with loading added or removed via the power electronics, not speed the engine up or down. A standard run of the mill power generator works that way, it doesn’t slow down or speed up based on load… the engine powering a generator tries to maintain a constant speed, feeding more gas to the engine as the load increases, less gas as the load decreases. The goal in an AC generator is to maintain cycles per second. Just my opinion… they could have it vary it’s speed but I doubt it. We had an ac generator that would drop to idle if it detected no load and then quickly speed up to running speed when a load was detected.
Aug 25th, 2008 (7:31 am)If you vary the speed of gas engine, you now are taking it out of the “sweet spot” which in the previous article was the reason you could get such great efficiency (see 50mpg article)
Aug 25th, 2008 (7:33 am)#2 capricorn, #5 Jim I, #6 Alexander, #8 Dick G,
Thanks for the responses.
I should have been more descriptive in my question.
I was thinking of a long highway trip of several hundred miles.
I would get the first 40 from the plug-in and the rest from the ICE.
Would it make sense that while the ICE was running, to charge the battery to 80% SOC and then shut off again. I would get the next 40 miles on battery alone, then the ICE turns on, charges to 80% SOC, turns off and I get the next 40 …………………. You get the picture.
This scenario, for me anyway, supports Jim I’s question in #5.
Aug 25th, 2008 (7:34 am)My first impression of this was…gee, I hope they arent overthinking this….
but looking at the big picture…I’ll agree w/ #3, they are being careful and thorough here… you’ve got to be able to make that battery last and use that ICE as efficiently as possible.
As a layman — I actually follow this logic and at the same time agree that the term “Customer Depletion Point” doesnt have to be so fancy — how about “Bettery Charge Level” ?
Aug 25th, 2008 (7:35 am)I have seen little talk about the actual genset itself. The gas part of the motor matters little. It is the generator part that matters what is that configuration?
gensets run at certain rpms to generate certain levels of electricity, as the load increases they up the RPM’s, however even gensets are not supposed run at full throttle for extended periods of time.
It would seem very practical to run everything at a certain rpm and then dip into the battery for certain levels of surge.
my guess is that they can spin the generator up to a certain level and then would need to go to the battery for max RPM’s.
anything over redline you could not sustain for very long with any engine.
GM is a car company so the know the tests.
I mean if i lived in colorado i doubt i would buy a 4 cylinder motor home as described!!
tomatolord
Aug 25th, 2008 (7:37 am)LyleL #19.
Thanks for the link.
I had no idea one could hear the whine of the electric motor on the EV-1. I wonder if the Volt will be that loud. I was expecting no noise at all.
Aug 25th, 2008 (7:39 am)So its exactly as others on this blog have surmised. Still its good to see it written down.
GsNed57.
I would expect the motor/generator to cycle on and off as needed.
Aug 25th, 2008 (7:40 am)This sounds very complex…how simple it sounds to make a BEV Volt. No E-REV, generator, etc. Once you’re out of juice, you’re out. Maintenance is much simpler. Volt 2.0 should be a BEV!
Aug 25th, 2008 (7:49 am)To me, there may be scenarios where you’re not using all the energy that the generator is creating to drive the vehicle. In those cases, that energy should be put back into the battery, even if it charges it all the way to 80% SOC.
Since the generator will always be on after you reach 80% SOC, why not take advantage of any extra energy being generated? The gas is getting burned anyway.
I’m not saying run the generator harder to charge the batteries, just to take whatever energy is available, if it’s avialable, when the generator is running at its lowest level, and stick it into the battery.
Aug 25th, 2008 (7:52 am)Actually, the Fisker Karma has a rtechnique similar, but more pronounced : by swithc the car to “High performance,” both the battery AND the generator supply power, in this case to provide fast acceleration, rather than any need for hill-climbing, as in the Volt instance. When the Vette goes plug-in, look for this feature.
Aug 25th, 2008 (7:57 am)I think the driver should be given the decision of how to use the battery when driving long distances. The drive should be able to select long range or normal. Normal being the above described mode and Long range would drain the battery based on demand and to maximize fuel savings with the ICE. If you added in some info from the driver like distance to be driven imputed to the computer that controls the ICE then you could use the battery to best advantage. This car begs for this type of control. We should not think of this as a battery only car. Real world driving means that we do drive long distances.
Aug 25th, 2008 (7:58 am)That explaination was certainly unexpected.
If what Mr. Farah says is correct, then the engine/generator needs to produce enough juice to power the vehicle at all speeds and grade inclinations; all of this while having the engine operate within a relatively narrow RPM range.
Secondly, according to the MotorTrend SOC chart, the engine periodically shuts off during “charge sustaining mode”. If the engine shuts off, how can the generator power the electric motor during charge sustaining mode ?
And, why do they call it “charge sustaining mode” when the battery really isn’t being charged ?
Aug 25th, 2008 (7:59 am)I think there is a misconception about running the generator and what happens to the juice if not needed by the car at somepoints . The juice will flow into the battery, not be “dumped on the floo” as
some think. The system doesn’t try to always maintain a charge at ‘exactly” 30%, that would be a silly thing to do, even if you could do it (you can’t).
Aug 25th, 2008 (8:08 am)#27 Eric C.:
“that energy should be put back into the battery, even if it charges it all the way to 80% SOC.”
Once you get to, e.g. 40% of SOC or whatever, then turn the ICE off and run back down to 30% SOC on pure electric. If you’re going I-40 westbound from Asheville, downhill into Tennessee, and regen gives you 80% for free, then by all means take it.
This article is making me wonder if I may have been wrong about throttle position on the 50 MPG thread. In any case, I would bet GM will figure out what scenario is the best in a given circumstance and program it into the system. I’m still guessing the ICE will cycle on and off sometimes.
Aug 25th, 2008 (8:09 am)A couple of points. Electrical generators can be configured so they generate more power as RPM increases, like the old bicycle generators we used as kids. They can also be configured to produce more power as speed remains constant but torque increases.
Yes, if because of a long period of hill climbing at high speed, you used up the battery capacity reserved for charge sustaining mode of operation, performance would drop off. Instead of using up to 120 KW, you would be only able to use up to 53 KW. But you could still get where you were going, only at a lower speed. But this circumstance seems rather hypothetical, because the design envelope will be able to handle the typical grades we encounter on an interstate with no performance degradation.
Aug 25th, 2008 (8:10 am)#31 Kent, This quote is what makes us question what happens to the extra energy once the battery is at %30 and you are running in ICE mode.
“And then when you take your foot off the gas, as an example when you’re done doing the merge, we had taken a little bit out and the battery has a little less in it. So what we’ll do then is we will opportunistically put that energy back into the battery either through regenerative braking or if we have to we will take some of the energy that’s not needed to turn the wheels and bring the battery up to the customer depletion level.”
He’s talking about bringing the charge back up to the CDL. But then he goes on to say they aren’t recharging the battery. Just a little confusing, but I think I understand what he’s getting at
Aug 25th, 2008 (8:10 am)Well, thank you for all your thoughts and comments. There is a lot of sense in them. But I think that even if Lyle got a very good info from A. Farah this is definitively not the whole story, we have to be patient and continue to ask what we think that is important.
JC
Aug 25th, 2008 (8:17 am)I think it’s a red herring to discuss what the Volt should do with the extra energy being generated (store it or dump it?).
Sure the Volt might generate a few extra watts here and there but it’s I really doubt it’s going to be generating so much power than it could actually charge the battery up. I would imagine GM will have an intelligent system that says ‘whoa, we’re generating 25% more power than needed. Let’s turn the generator down a few notches’.
GM is going to have some way of controlling the power output of the generator (whether that’s through variable RPM or variable throttle position). It seems only logical that the Volt will be regularly adjusting the output of the ICE to match the generators needs. Accordingly, there might be a temporary surplus of power that gets you to 32%. It would be silly to dump the power (waste it) or to store the power (lose opportunity to charge electrically) when a simple solution like turn down the generator exists. I think we can assume they’ll do this and the real question is how.
Aug 25th, 2008 (8:18 am)_____________________________________________________
The VOLT program is without a doubt helping GM gain a stronger industry leadership position both in terms of meaningful innovation and positive consumer perception. This will result in more cars sold.
Here is another opportunity for GM to demonstrate industry leadership:
GM should consider being the first automaker to announce that they are making a PV Cabin Exhaust standard on ALL GM cars. If GM did this, it would force other automakers to follow suite and GM would be positively credited with setting this standard. GM should take the opportunity to do this before some other large automaker takes the lead on this item. It is also just simply the right thing to do.
Here is today’s reason for PV Cabin Exhaust as a standard feature:
http://www.foxnews.com/story/0,2933,409721,00.html
I have heard the argument on this blog site and other venues that a PV Cabin Exhaust will invite additional child-left-in-car deaths due to people intentionally leaving children in cars because they will assume the PV Cabin Exhaust will keep the children safe from over-heating. This erroneous argument is similar to arguing that we are better off not having air-bags in cars because in encourages people to drive more recklessly. Are we better off without ABS brakes and seat belts? How about removing engineered crumple zones because it fools us into a sense of security?
Placing a PV Cabin Exhaust on all GM cars as a standard feature will drive the per unite implementation cost way down and will be a very positive selling feature especially for those prospective customers tired of getting into “oven” cars during the summer months (think Florida, Georgia, Texas, Arizona, Nevada, etc…).
A PV Cabin Exhaust as a standard feature would be a tipping feature for me any many other car buyers.
_____________________________________________________
Aug 25th, 2008 (8:19 am)#7 nuclearboy asks: “I wonder what happens if you deplete the battery to 30% and then start up a large mountain chain with 4 heavy passengers and a clamshell full of luggage on the roof? The battery would be called on for extra power but the regen braking would not make it up.”
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Sure, I can answer this with some simple math.
We know that the gas engine generator’s maximum output is around 53 Kw. For the peak power from the electric motor, we’ve heard numbers of 100 Kw and 120 Kw, so let’s call it about 110 Kw. This means that when you floor it uphill, the batteries will have to produce about 57 Kw.
We know that the total energy storage of the battery pack is 16 KWh, so if the customer depletion point is 30% SOC, that would be 4.8 KWh. So the amount of time the Volt can deliver peak power would be 4.8 KWh / 57 Kw.
Bottom line: if you constantly floor it uphill, you’ll be able to go around 5 minutes before the batteries completely drain and you lose peak power.
Note that this assumes that there are no level or downhill parts of the grade and you’re flooring it all the way. If there are downhill parts of the grade, the extra weight in the vehicle would make regen braking work better.
So this corresponds to a very long steep mountain road, something like a 5 mile 6% grade. The only such road I know of is going west out of Death Valley, CA. In this case, there are pull-off areas with running water to cool off your radiator, or if you’re going down hill, so you’re brakes can cool down. The point is that regular cars also have problems on such grades, so the Volt is not alone here.
Aug 25th, 2008 (8:25 am)Re: post 17, dagwood55, et al…..
Question: Could a Volt weighing 4,000 Lbs including passengers climb a (steep) 6% grade up a 10,000 ft mountain using only ice/gen power?
Answer (approximation):
Power(Hp) = [F(lbs) x V(mph)]/375* = (4,000lbs x 4.2mph**)/375
= 44.8 Hp (….or 44.8 x 746 = 33.4Kw)
Therefore, a Volt should be able to climb a steep mountain (6% grade) at a steady speed of 70 mph, with reserve power & without need for battery assist. Since there is an ample power margin, a climb of 10,000 ft should be achievable even at 70 mph.
**(Assumes the velocity is 70mph up a 6% grade, so the vertical velocity would be 6% x 70mph = 4.2mph)
*375 is a constant for force in pound feet & velocity in miles/hr
Aug 25th, 2008 (8:27 am)#36 Dan Says: “GM is going to have some way of controlling the power output of the generator (whether that’s through variable RPM or variable throttle position). It seems only logical that the Volt will be regularly adjusting the output of the ICE to match the generators needs.”
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Yes, GM said this last summer:
http://gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/
Also, just as you say, there is no wasted electricity. If the ICE/genset temporarily generates more power than required, it will charge the battery very slightly, and then the ICE output will be decreased to discharge the battery very slightly, maybe a couple of percentage points around the customer depletion point.
Aug 25th, 2008 (8:29 am)Okay, this may be a dumb question, but if the depletion point is 30%, then is the all electric range somewhere around 28 miles (40 mile all electric range minus 30% of 40 miles (12) ?
Aug 25th, 2008 (8:32 am)Did we all read a different post?
Where does it actually say that the generator won’t stay on until 80% SOC?
All-in-all, a nice glossing over of some of the major problems with the Volt design (i.e. hauling around 1/3 of the battery that you never really get to use in all-electric mode).
On the flip side, if they are not getting the range they want, I am pretty sure that 30% will become 25% or 20% to make up the difference.
Aug 25th, 2008 (8:32 am)#39 nasaman,
If this is true, then the Volt is over-designed.
Do your numbers account for aero or rolling resistance? Would this be significant? Are there other factors?
Aug 25th, 2008 (8:33 am)Regarding the conversation on how the Volt will handle extended climbs (i.e. I-40). It seems to me that even crossing the rockies in a fully loaded down Volt is not going to require (on average) more power than the 1.4L engine can generate (on average). It’s not like it requires full throttle at all times to cross the rockies.
I bet GM has figured out what the highest sustained power draw is that you could expect to encounter and it has made the ICE capable of delivering that indefinately. In other threads, poster have provided info on the HP required to cruise around 60-70mph. If I recall correctly it was around 20-30hp. Accordingly, I can’t imagine you’d need an average higher than 50-70hp to climb a mountain pass.
Maybe I’m wrong and if so, once your battery was depleted to the ultimate cut off point (20%?) then you’d simply be limited to the power output of the ICE which is what, 80-90hp?
Aug 25th, 2008 (8:33 am)(PS: My calculations in post #39 are an approximation because they neglect the Hp needed to propel the Volt on a horizontal road; however, I would estimate the Hp needed to move the Volt at a steady 70mph on a flat surface would be <20, so the conclusion of post #39 should still be OK or very close to OK)
Aug 25th, 2008 (8:36 am)#41 benson asks: “Okay, this may be a dumb question, but if the depletion point is 30%, then is the all electric range somewhere around 28 miles (40 mile all electric range minus 30% of 40 miles (12) ?”
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The 40 miles AER only represents 1/2 of the available energy in the battery. See here for details:
http://gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/
By the way, the figure of 28 miles is important. This is about how long you can run on batteries after you run out of gas.
Aug 25th, 2008 (8:41 am)Two points:
1) There must be a deadband around the targeted 30% SOC.
2) GM should allow operating mode selection by the driver.
1) Deadbands are used to eliminate inefficient starting and stopping of the range extending engine (say 30% to start and 35% to stop). GM is certainly testing different deadband widths against different driving scenarios. No one approach can effectively fit all use cases.
2) If GM would mistakenly only support one approach, say the more general one described above, then an owner who reaches the foot of the Appalachians or the Rockies at 30% SOC will conclude that the Volt is a worthless piece of trash. The vehicle will quickly exhaust its remaining charge as it begins to climb and then will slowly crawl along in the truck lane in a patheticly embarassing manner. By the time the owner eventually reaches the top of the climb, they will likely start looking for a cliff to shove it off, and I wouldn’t blame them.
Instead, GM should offer the driver a selection of operating modes so that they can “inform” the car of the expected use case for that drive. In this way, an “energy saving” operating mode like the one described above (flat, start and stop, low speed) will still be available to produce exceptional efficiency.
On the other hand, a “power intense” operating mode (hills and mountains, constant high speed, racing) could be available when needed. This latter operating mode might attempt to keep the battery fully charged (80% SOC) at all time using the range extending engine. This would give the Volt the best chance of keeping up with other traffic along the entire hill climb.
These operating mode selections should be able to be changed easily by the driver while the car is in motion. Displays should reflect which mode the car is in, and how well the operating mode targets are being maintained (an infinitely long hill climb will still eventually drain the Volt’s battery). In this manner, the new Volt will appeal to a much larger audience across all regions of the U.S.
Aug 25th, 2008 (8:42 am)#44 Dan Says: “Regarding the conversation on how the Volt will handle extended climbs (i.e. I-40). It seems to me that even crossing the rockies in a fully loaded down Volt is not going to require (on average) more power than the 1.4L engine can generate (on average).”
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Three points:
1) It’s not the average, but the peak power required for long constant uphill grades that may be a problem.
2) The 1.4L engine in the Volt is tuned for efficiency, not power. It will use an Atkinson cycle and only generate around 70hp max. The remaining peak hp comes from the batteries.
3) I believe the I-40 example includes many level and downhill sections where the batteries can recharge.
Aug 25th, 2008 (8:49 am)The scenario Volt chief engineer Andrew Farah described makes sense for commuter situations, where one is close to home where the Volt can be recharged. But, what does he say about long highway trips described by #21 Rashiid Amul?
I agree with Rashiid when he said “It would it make sense that while the ICE was running, to charge the battery to 80% SOC and then shut off again. I would get the next 40 miles on battery alone, then the ICE turns on, charges to 80% SOC, turns off and I get the next 40 …………………. You get the picture.”
#47 hermant makes a good point. I would add long trips to his list of operating modes.
Aug 25th, 2008 (8:55 am)you should have the option (switch) to recharge the battery fully if you want to. If you were going on a longer trip you may want to leave the engine runing to complete the charge.
Aug 25th, 2008 (9:00 am)I raised the issue several months ago about the repetitive starting of the Volt ICE (particularly on long trips with the scenario described by Andrew Farah) and the long term effect that it will have on the ICE, but never got an answer.
Perhaps one of the ICE engineers might care to comment.
Aug 25th, 2008 (9:02 am)I agree with #50 Dale, assuming “complete the charge” is to 80% SOC.
I would envision the “operating mode” option being set through the touch screeen rather than a manual switch.
Aug 25th, 2008 (9:02 am)capricorn Says: @2
I believe you hit it right on the nose. If the motor/generator is capable of maintaining the battery at about 30%, that’s the way to go to gain full advantage of a plug-in.
Aug 25th, 2008 (9:04 am)It seems to me that GM wants to limit the number of charge cycles during the battery pack’s lifetime, thus not allowing the ICE to charge the battery once the customer depletion point is reached. Now, the batteries will have only one or two charge cycles per roundtrip instead of several cycles that will effectively lower the battery life. GM is heavily protecting the degradation of the battery…
As for the mountain discussion, yes, uphill is a concern yet I am confident that GM will address this issue. When I worked in the automotive industry, every vehicle I was a part of was tested in the Rockies in order to calibrate the ECU for the high altitude. So, designing for the mountain terrain has always been a must in all cars. Another thing to add is that the MPG will be significantly lower when coming back down the mountain with regenerative braking and coasting. I wonder if the ICE will come on at all at some points when my Volt is rolling down the mountains back to Denver….
Aug 25th, 2008 (9:14 am)#54 Aspherical said:
It seems to me that GM wants to limit the number of charge cycles during the battery pack’s lifetime, thus not allowing the ICE to charge the battery once the customer depletion point is reached.
______
Perhaps I had misunderstood, but isn’t it GM’s goal to limit the lifetime number of charges to 100% SOC rather than limiting the number of charge cycles?
Aug 25th, 2008 (9:14 am)#42 GXT
“All-in-all, a nice glossing over of some of the major problems with the Volt design (i.e. hauling around 1/3 of the battery that you never really get to use in all-electric mode).”
From what I’ve read, not using 1/3 of the battery is necessary for a long battery life. Using all of the battery’s stored energy would not be in your long-term best interest.
Aug 25th, 2008 (9:21 am)The term customer depletion point must be a carry over from the decisions to close some of the pickup plants, try to sell the Hummer line, and sell the midsize truck line to Navistar.
Aug 25th, 2008 (9:25 am)#56 ThombDbhomb
Isn’t it the “deep discharges” to/near 0% SOC and the number of “full” charges to 100% SOC that have a long term negative effect upon the battery life?
I don’t recall reading that multiple charging cyles to keep the battery between the approximate range of 30% SOC and 80% SOC as having a long term negative effect upon the barrery life.
I might be wrong on that. If so, perhaps others can clarify that point.
Aug 25th, 2008 (9:27 am)I think we will have to wait to see the different modes they end up using. The battery will be part of the circuit when the generator is running. They will try to match the generator as close to the motor demand as possible but any extra output will be used to charge the battery just like any sudden motor demand will discharge the battery.
I wish they would show a graph of where all the energy is going like they do for the Prius. Even if it’s not the default screen, us technical types want to know everything!
Aug 25th, 2008 (9:34 am)I have read this entire thread. There is still confusion here. One of the very last posts still advocates using the ICE on long trips to charge the battery. Here is my take for what it is worth.
In over 99% of the cases, using the ICE to charge the battery makes no sense. To extend the range, you run the ICE, but since a HPhr of energy generated by the ICE costs about 3 times as much as a HPhr of energy drawn from the battery, you want to run the ICE as little as possible, and arrive back home with a battery depleted down to 20-30%. You then charge it up with cheap electricity, rather than using expensive gas to charge the battery.
In other words, you run electric for 40 miles or so. When the battery gets down to 30%, the ICE kicks in, and runs at constant RPM. If you are driving on the level, or with balanced ups and downs, the ICE generates surplus power, which goes into the battery. If you generate enough surplus power, the battery will charge up to some setpoint, programmed into the computer by GM, say 35%. At this point, the ICE should shut down until the battery gets down to 30%. To keep running the ICE just to charge the battery is a waste of expensive gasoline.
The one exception which looks to me like it could be legit, is what if you are facing a trip over the Smokeys or the Rockies, or some other extremely long uphill pull. The above scenario would still work, but if you ran the battery down to the point where you could draw no more power, the car’s HP output would be limited to that of the 1.4l ICE, with no surge assist from the battery. In other words, the car would slow down on very steep hills, and accelerate sluggishly.
This is not a disaster, but GM may be working to quantify this effect, and determine if it is worthwhile to provide a “build reserve charge” mode. This would be needed only in extreme cases, and would require some foresight. The driver would need to recognize the need to build extra charge while driving to the foot of the mountain, and invoke the “build reserve charge” mode. Futuristically, the GPS could interface with the car’s computer, and do this based on destination, and known distance and elevation changes.
But if you invoke the “build reserve charge” mode when you don’t need it, you will waste a lot of gas. This is because you will run the ICE to build up a charge which stays in the battery until you get home, and you find yourself at home with an 80% battery charge built up with expensive gasoline, that you can now do much more cheaply by plugging in to the grid.
Aug 25th, 2008 (9:38 am)I don’t think the number of charge cycles of the batteries are going to be an issue. As with Cell phones … people either will plug them into the chargers all the time / as often as possible … to keep a “full” charge …. or…. they run them right down…then plug in..
I will be plugging my Volt in every time I return to the office… I am in and out a 1/2 dozen times a day… short runs (5 KMS) and longer runs (up to 160 KMS) … and this is every day… For me to maximize the benifits of the batttery …. I will want it always “topped up”..
Aug 25th, 2008 (9:41 am)Very good article Lyle.
So there will be parallel electrical paths.
1 – Engine to battery to wheels
2 – Engine to wheels
Anytime you go through the battery, there’s a charge-discharge efficiency loss so you’d prefer to skip this whenever possible. This method makes sense to me. Great job GM.
Aug 25th, 2008 (9:42 am)#59 Texas said:
The battery will be part of the circuit when the generator is running. They will try to match the generator as close to the motor demand as possible but any extra output will be used to charge the battery just like any sudden motor demand will discharge the battery.
_____
This suggest that some of the generator output will be sent directly to the electric motors, bypassing the battery. I recall hearing this speculation before but don’t recall GM specifically stating this is as fact.
If it is otherwise and 100% of the generator output goes to the battery, then everytime the ICE starts it results in a battery charge cycle, even though the charge might be small and of short duration.
Aug 25th, 2008 (9:44 am)#58 Estero
That was the point I was trying to make to GXT. You and I agree.
Aug 25th, 2008 (9:53 am)Andrew Farah said:
Q: How will the vehicle’s propulsion system work when you get to the customer depletion point?
A: When you get to the customer depletion point, the engine will come on seamlessly as it’s supposed to…The engine comes on to make enough electric energy to turn the wheels, because the wheels are always turning electrically.
_____
If the above is true then doesn’t it mean the ICE will run indefinitely once it comes on? Or, am I missing something here?
Aug 25th, 2008 (9:57 am)As long as I can use the Volt for emergency backup power for my home, to power tools in the field or on my camping trip, I’m happy.
I can’t……
(nevermind)
by the way, here is an EXCELLENT video about Digital Rights Management– or what ZDNet Executive Editor David Berlind calls C.R.A.P. (Content Restriction Annulment Protection) — has enabled companies like Apple to lock music downloaded through their service into their own devices. Berlind describes an effort to create a DRM standard so content can flow seamlessly between multiple devices.
http://www.youtube.com/watch?v=Ww65z8HuIJ8&feature=user
If Apple sets the standard as I-Pod, they also set the (high) price of the media content. “DANGER Will Robinson…”
Aug 25th, 2008 (10:03 am)#42 GXT said:
Where does it actually say that the generator won’t stay on until 80% SOC?
_____
It wasn’t mentioned in this interview with Andrew Farah. But, the charge range was mentioned in another interview several months back.
#64 ThombDbhomb
We do agree. Now, I’m interesting in hearing what others have to say about my #65 posting.
Aug 25th, 2008 (10:09 am)Does that mean if you are at 30% Battery and the ICE is running, but it stops running at a red light?
Aug 25th, 2008 (10:12 am)This begs the question, “If you have a propulsion system in which a small efficient gasoline engine powers an onboard generator which in turn supplies electrical energy to an electric motor to propel the car at 50 mpg, why would you not employ this system as a mainline powerplant without the expensive batteries?
Of course you would need a few batteries perhaps to help with peak power load conditions, but nothing on the scale of 40 miles AER.
This is the same principle behind diesel/electric locomotives. It would seem that GM is in the process of perfecting that system for automobiles. Is their something they are not telling us? Are they actually planning on rolling this out as “e-flex light” in other production vehicle(s)?
Aug 25th, 2008 (10:13 am)#45 nasaman Says: “(PS: My calculations in post #39 are an approximation because they neglect the Hp needed to propel the Volt on a horizontal road; however, I would estimate the Hp needed to move the Volt at a steady 70mph on a flat surface would be <20, so the conclusion of post #39 should still be OK or very close to OK)”
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Actually, GM said last summer that “Peak efficiency (of the ICE) will be at around 30 kW, which is what the car should require at 65 mph slightly uphill, although the actuals of mass and energy requirements are not final yet.”:
http://gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/
Given that the mass seems to have increased, and the aero seems a bit worse than expected, I would say 30Kw for 70mph on level ground is about right.
Aug 25th, 2008 (10:15 am)If I wanted a pure EV with a 68 mile range could I just run without gasoline?
Aug 25th, 2008 (10:17 am)This article gets me to question how the batteries are segmented. Once the customer depletion point is reached, will only a certain segment of the battery pack be charged (to 80%, for example) by the generator to run the wheels, leaving the other plug-in segment of the battery pack at 30% to preserve the life? We have been treating the battery pack as if it was a giant AA battery. I would be interested in knowing how the battery pack is segregated internally. This could answer alot of questions in this post.
Aug 25th, 2008 (10:17 am)#69 Voltme
Hmm, a pure gas/electric Volt sounds interesting.
I agree, if you can do without the 40 mile AER, why not just toss the battery and add a little larger generator ?
Am I the only one that would like to see the price of this car reduced by $10,000 ?
Aug 25th, 2008 (10:20 am)The primary confusion is whether the ICE will run at constant RPM. I have seen conflicting answers and support info for each. Does anyone have the definative word on this?
Otherwise the question by KUD @ 68 is a good one.
Aug 25th, 2008 (10:21 am)#69 Voltme Says: “This begs the question, “If you have a propulsion system in which a small efficient gasoline engine powers an onboard generator which in turn supplies electrical energy to an electric motor to propel the car at 50 mpg, why would you not employ this system as a mainline powerplant without the expensive batteries?”
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This question has been asked many times before.
The answer is that you still need a lot of battery power to supply the peak HP. The gas engine only supplies average HP. The electric motor and batteries supply peak HP. So you need a fairly large sized battery pack to make the E-REV (a.k.a. series hybrid) design work, even if don’t need the all-electric range.
Aug 25th, 2008 (10:23 am)# 60 Tom Harwick
I think, that „energy intensive mode“or “mountain mode” should not mean 80 % charge. Should be enough 50 % or even 40% when engine kicks in. 5 mile 6% grade is very exceptional case and can be handled by IEC when in the end of elevation little bit slowing car. In case you keep 80% charged battery there will be no room for regenerative braking on downhill. Let’s assume that normal driving capacity on highway is 12 kW (60 mph). I think on the slope average IEC load will be not more than 35 kW. Very short load increase can be when accelerating on the slop uphill and will be handled by the 40% battery reserve.
Aug 25th, 2008 (10:28 am)#74 MetrologyFirst asks: “The primary confusion is whether the ICE will run at constant RPM. I have seen conflicting answers and support info for each. Does anyone have the definitive word on this?”
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No. There has been no definitive answer on this.
GM said last summer that it would be variable RPM:
http://gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/
(see last paragraph or article)
And then Bob Lutz just said on the Charlie Rose interview that they were thinking about a single RPM engine:
http://gm-volt.com/2008/08/20/lutz-production-volt-has-a-cd-between-28-and-29-and-battery-extreme-cold-performance-is-good/
(about 7 minutes into interview)
Lyle: Is there any way you could get GM to answer this question?
Aug 25th, 2008 (10:31 am)#76 Darius
How much energy is it that can be reclaimed through regenerative braking? I’m sure going down a mountain is different than normal city/highway driving, but I have no feel for the amount under different conditions. What is the formula?
Aug 25th, 2008 (10:33 am)Dave G,
You are to pessimistic about 30 kW at 70 mph. In that case 40 miles “all electric” range for Volt s not valid at all.
In that case you can easy calculate “real range” 40 miles x 8 kWh (battery effective capacity) / 30 kW = 18,6 miles (all electric range).
Aug 25th, 2008 (10:37 am)I will wait until I see the actual schematics to see how everything is hooked up. Like any marketing guy would know that. Parallel paths for a direct generator to motor connection and then a separate circuit to the battery to handle excessive demand and over generation? I don’t know about that. Again, I will wait to see what they come up with. I’m guessing it will all just be connected. It would be a lot easier and I don’t see a reason for doing any different. The motor will draw what it needs from the circuit and they can match the output from the generator fairly closely (but not perfectly). The net charge on the battery would (could) be very small.
This way they could just change the modes by running the generator harder, longer or both without messing with any multiple circuits. Am I missing something?
Aug 25th, 2008 (10:38 am)#71 Belloc asks: “If I wanted a pure EV with a 68 mile range could I just run without gasoline?”
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Good question!
From what I understand, it would work that way. When you run out of gas, you still have another 28 miles of battery to get you home or to the gas station.
However, frequently discharging the battery significantly below 30% will wear out the battery much, much faster. So it will become a warranty issue. If you constantly run without any gas in the tank, then when (not if) you have to replace the battery, they will probably check to see how you’ve been using it. If you run it without gas a lot, it will probably void your warranty, and you’ll have to pay the $10,000 for a new battery yourself.
Aug 25th, 2008 (10:42 am)#78 Estero,
NASSAMAN calculated that on the 6% slope average capacity need is 33,5 kW. On the flat road (or to cover normal friction) we need 12,5 kW. The difference between those two figures woul be reganarative braking capacity (~20 kW) on the 6% long downhill slope.
I have to leave for now.
Aug 25th, 2008 (10:43 am)#32 Fahrvergnugen Fanboy,
I agree that it would make sense to turn the generator off if it reached a higher limit, but I thought GM had previously said it would not turn on and off.
Aug 25th, 2008 (10:43 am)#79 Darius Says: “Dave G,
You are to pessimistic about 30 kW at 70 mph. In that case 40 miles “all electric” range for Volt s not valid at all.
In that case you can easy calculate “real range” 40 miles x 8 kWh (battery effective capacity) / 30 kW = 18,6 miles (all electric range).”
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That’s true! I didn’t think of that.
So what GM says here doesn’t seem to make sense:
http://gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/
Aug 25th, 2008 (10:46 am)#1 Rashiid – ” What was the reason why they can’t charge the battery up to 80% SOC with the ICE? I honestly can’t remember the reason.”
Greg Woulf #16 has it right that it’s about harming the battery. However, it’s not that the charge would harm the battery, it’s the *number* of charges over the lifetime of the battery pack which are the problem.
A123 claims its battery pack can be cycled 7000 times at 1C before it loses 20% of its capacity. GM can’t count on the 1C discharge, and it would like a margin of safety on the life of the pack, so it wants to limit the cycles below 7000.
Now it’s just arithmetic. With 365 days in a year, if someone charged and discharged once a day you get to 3000 cycles. But the possibility exists that someone (like you) might charge the pack twice in a day — once before going to work and once at work. The possibility also exists that someone like Statik would be doing 90 mph with jackrabbit starts, discharging at over 1C. In these cases you are looking at 7000 cycles, with potentially some of the discharges above 1C.
Given this, the last thing GM wants to do is add cycles on a long trip. For example, if you went 100 miles and the battery was completely discharged and then recharged once during the trip, you’d have two cycles per 100 miles. Do the same on the return trip and you have four cycles per day. Four cycles a day would turn into more than 1000 cycles per year just commuting five days during the week. That would be over 10,000 cycles during a ten year period, way above the limit of 7000.
BTW, the cycle issue is why, if the energy density of the battery doubles, the range could conceivably quadruple.
Aug 25th, 2008 (10:47 am)#73 Dazed and Confused,
See post #75.
Aug 25th, 2008 (10:48 am)Will the ICE be running all the time after customer depletion point ?
Or will it be off at certian times ?
We know ICE mode graph that GM provided us sometime back says that ICE will be off at certian times. Did this change now ?
Aug 25th, 2008 (10:51 am)#85 DonC
I agree. It’s not that the battery can’t be recharged to 80% by the ICE, GM wants to limit the number of cycles of the battery pack. As I stated in post #54, GM is heavily protecting the degradation of the battery…
Now, I am wondering what percentage of the battery pack is “charged” by the generator once the customer depletion point is reached. I am not convinced this battery pack acts as a giant AA battery. I want to know if there is a “plug-in” battery segment and a “ICE-generator” segment of the battery pack. I doubt GM will answer this question before the Volt is officially unveiled…
Aug 25th, 2008 (10:51 am)30% was stated to have changed to 35% so this is probably accurate (other than the 30% part) information but old interview material.
As usual answers lead to more questions. What happens when you reach the foot of a mountain range and you battery is already depleted? No way the battery isn’t depleted to 0% on the climb, right! well maybe maybe not if you think about it. When depleting the battery even further the ICE is doing probably a good portion of the work. Still we need clarification on this issue which has come up a few times before.
Also what happens when you have the car stopped in traffic at a light and you are at 30% SOC! Surely the battery will rise above 30%. How far before the ICE turns off?
I guess we have two years to get all these answers. [shrug]
Aug 25th, 2008 (10:57 am)# 60, I like the “build reserve charge switch, but why not take it a step further?
If the volt had a “smart gps” with road elevations and climb gradients in the database, it could manage the battery reserve for you. For example, say you’re headed out on a vacation from Wichita Kansas to Aspen Colorado. And you’ve punched in the destination and approved the route on your built in touch screen GPS.
1. First 40 miles out of wichita is on battery only.
2. Next 400 miles or so the battery is maintained at 30% SOC by the lightly loaded ICE, achieving the advertised 50mpg along the flat I70 (nothing else to look at here, so you might as well play with your ipodish features on the volt dash)
3. Somewhere in eastern colorado, the ICE now starts to load heavy (with a corresponding drop in fuel economy) while it brings the battery up to an 80% or better SOC by the time you get to the other side of Denver.
4. During the climb from Denver to Aspen, the ICE continues to work furiously (high loading) but is able to hold the battery to a slow bleed, (perhaps slightly limiting acceleration when you’re passing the Ford Excursion). Your battery SOC slowly depletes from 80% down to 30% by the time you reach Aspen.
It seems there would be plenty of scenarios where a gps with elevation data would be quite helpful in managing the volt’s ICE/generator/battery.
Aug 25th, 2008 (10:58 am)re: #85 DonC
What you say makes sense. Could you define for the rest of us what the “number” of charges over the lifetime of a battery really means?
Does, for example, every minute charge through regenerative braking or a larger charge resulting from the ICE running have the same effect upon the battery as one that would take the 30% SOC to 80% SOC? If different, how so?
Aug 25th, 2008 (11:01 am)To the best of my knowledge, this is the first time that it has been reported that the ICE will come on to run the generator vs charging the batteries. Previous articles have (perhaps erroneously as Mr Farah actually refers to in his response to Lyle’s question) stated that the purpose of the engine is to recharge the batteries, not run the generator.
More information is needed, but it appears from these comments that the main purpose (perhaps only purpose actually) of the ICE is to run the generator.
Can someone help with this question? Is the generator always directly linked to the wheels or does it only supply power once the CDP is reached?
Aug 25th, 2008 (11:03 am)You guys are making this layman’s head hurt…
Its all ball bearings anyway, right?
Aug 25th, 2008 (11:06 am)Take this scenario. There are three segments of the battery pack.
1. Plug-in only
2. Generator only,
3. Regenerative braking only, only releasing energy once 80% charge is reached.
This would reduce the number of charge cycles each battery cell would see. Does anyone see a problem with this scenario?
Aug 25th, 2008 (11:10 am)#60 Tom,
Guess I could have read your whole post which included:
“Futuristically, the GPS could interface with the car’s computer, and do this based on destination, and known distance and elevation changes.”
Anyway, . . . yeah, what he said.
Aug 25th, 2008 (11:11 am)#75 Dave G:
Actually, the “Peak Buffer” as described by Farah in the post above, can do it’s job at only 30% SOC, therefore, even if we assume that all 30% is needed for the buffer (which is actually never going to be the case since that would drastically alter the battery lifespan), then you need a battery capacity of 4.8 kw (I’m assuming the Volt has a 16kw battery and at 30% you have 4.8 kw left).
The real world battery capacity would likely be even less than that…
Aug 25th, 2008 (11:18 am)I thought I understood what the typical charging sequence would be both in commuter mode and in hill climb mode, until I read the previous 89 posts…
I thought that the state of charge would be drawn down from 85% to 35% using all electric power. At 35% (and here there may be an override command to force the ICE to kick in early if you envision a hill climb) the ICE kicks in and runs at a steady rpm til the battery is at 40% (or 45%, but the chart made it look like a smaller amount). Most of the juice would go to the wheels but a lot would charge the battery. The battery reaches 40% and the car operates all electric again for 5% or about 4 miles. The charge depletes to 35%, and it starts over. The ICE will not charge to 85% unless GM allows it, but it would be an override command with limited utility since the goal is to use cheap, US produced electricity, not expensive foreign oil. Even a long hill climb can be worked around by simply allowing the driver the ability to keep state of charge a bit higher, i.e. cycling from 50% to 55% instead of the usual lower numbers. Even if I am crossing Logan Pass in Montana, I will not be ‘flooring it’ all the way, so the ICE will furnish almost all the electricity needed to drive the wheels. I think Nasaman summed it up pretty well.
Different battery types have different strengths and weaknesses, LiIon can be used thousand of cycles with little degradation if the cycles are shallow, hence the problem with the ICE charging the battery all the way up as several posters have stated.
All in all, it sounds like GM can have a great car, a game changing car, if they deliver what they are talking about, with a degree of luxury and finish at a reasonable price.
I only use 600 gallons a year as it is, so it will take a long time for $45,000 Volt to pay for itself without significant government encouragement. I am a bit of a libertarian, (small l), but the stakes are so high that I think it is worth making an exception and the government should increase the tax incentive for Volt type, EREV vehicles, to $8,000-$10,000, for the first 30,000 produced per calendar year. Then rethink, possibly increase, those numbers when Volt and IMiev production gets past that level. We need to get off foreign oil ASAP. Build wind generators, photo voltaics, nuclear power, clean up the older coal plants, get geothermal on line, build everything, but the crux of the matter is reducing our reliance on foreign oil for transport, and EREVs and BEV’s are the only way to do that.
Aug 25th, 2008 (11:25 am)#45 nasaman
I’m thinking the guess of < 20 hp seems a tad optimistic. If you use 1700 Kg for mass, .5 for the CdA (optimistic?), .012 for the rolling resistance (optimistic or pessimistic?), and 1.225 Kg/m^3 for the density of air (not realistic but no way to know), at 70 mph (32m/sec) the Volt would need about 22,800 watts or about 30-31 hp to overcome aero drag and rolling resistance. (515 N from aero drag and 200 N from rolling resistance).
Aug 25th, 2008 (11:34 am)I can’t believe this……
If your in a situation where you need a vehicle to climb mouantins for sustained periods, more than 1 time a year (or maybe in your life). Then you should probably buy an SUV, that way if there’s traffic you can take a shortcut through the woods.
PS
Please unsubscribe from the waiting list so i can move up. I live in the other 99% of the country where that’s not an issue.
Aug 25th, 2008 (11:42 am)The question commonly being discussed here (Will the ICE charge the battery with its excess power?) doesn’t seem like the right question to be asking. Regardless of the answer, a more fundamental question exists: Will the Volt dump the generators excess power or will it adjust the generator output to match the cars needs? This is what really matters because on a long trip, regardless of whether or not the ICE charges up the battery, you’re going to reach a point where charging the battery isn’t an option….and then what? Does the Volt dump the power or does it reduce the generators output?
The answer to this question seems obvious. If the Volt can’t adjust the generators output then that’s just wasteful and poor engineering…something I can’t imagine GM would do. GM has hinted several times that the generator will have different power output levels so I believe we can assume it will. It makes no sense the other way. If the power output isn’t variable, GM would have to have the generator cranking out max hp to meet worse case scenario needs at all times, which is just silly.
If the Volt can adjust the generators output, then it only makes sense to use this all the time, rather than to use expensive gasoline to charge the battery and then switch into this more efficient mode. So we can assume the Volt will not be giving the battery a complete charge (unless if the owner was able to specify that with an ‘upcoming mountain’ mode).
The only real question that remains is what the car will do with a temporary surplus of power, but this answer also seems obvious, the car will store it so it has power available for demanding conditions. The article we’re all discussing has pretty much stated this:
“…we will take some of the energy that’s not needed to turn the wheels and bring the battery up..”
So basically, it seems very likely that the generator will have variable output levels that will not create a significant surplus of power over an extended time period. Temporary surpluses will be stored, but if those surpluses accumulate to a significant amount the car would simply run at a lower generator output level for a while to use that up. So we’d never see the battery getting much higher than a few percent above the 30% (or 35%) electric cutoff point.
Aug 25th, 2008 (11:42 am)#99 JonP
Uh… no.
Aug 25th, 2008 (11:44 am)56. ThombDbhomb,
58. Estero,
ThombDbhomb wrote:
“From what I’ve read, not using 1/3 of the battery is necessary for a long battery life. Using all of the battery’s stored energy would not be in your long-term best interest.”
So there are two design problems and not one
Do we know what % of the battery should remain unused to ensure long life? I don’t believe 30% has ever been stated.
The issue is that Toyota/Honda will be able to use a battery that is much smaller than the Volt’s (and therefore seriously undercut the Volt’s price) and get pretty much the same net results.
Aug 25th, 2008 (11:47 am)By its design there will come a point where the battery is completely drained if I have multiple continuous grades to climb past the depletion point. Is that what I hear from this article? There is no way to charge the battery other than plug-in and braking. The ICE is just producing enough electricity to propel crusing speed and nothing more (charging battery). Sounds really wimpy to me! Is this another cop out measure by GM?
Aug 25th, 2008 (11:47 am)#88 Aspherical – I missed #54 where you beat me to the point that it was the number of cycles. There will be one pack not two.
#91 Estero – a cycle starts with a 100% charge, then discharges to 0% charge, and then recharges to 100% charge. There is also a rate of charge, with 1C having the cycle occur over an hour, 2C in half an hour, .5C in two hours. The higher the C rate the fewer cycles a battery can handle. Temperature is also a factor.
By only using half the pack (depth of discharge of 50%), GM is essentially doubling the number of cycles the battery pack can handle as well as limiting the discharge rate. (As the battery pack delivers more range you don’t need to limit the DOD, which is why Tesla can get a range of over 200 miles).
Regen and charging from the gen-set count but they’re going to be minor factors. First they are are not going to change the SOC appreciably. Second the rate of charge (C rate) will be way less than 1.
Aug 25th, 2008 (11:48 am)67 Estero,
I have heard the 30-80% range before, what I am wondering is why the first several dozen posters seem convinced that the generator will no longer charge the battery to 80%. I don’t see that stated anywhere.
Aug 25th, 2008 (11:50 am)I didn’t read all the posts but enough to see that there are some misunderstandings about IC engines and fuel usage. Which uses more gas? An IC engine running at 2000 rpm or the same exact IC engine running at 3000 rpm? The answer is you don’t have enough info to answer the question. The IC engine will use very little power if all it is doing is idleing and turning the AC compressor. There is no “wasted” power per se that could be used to also charge the battery. Additional load in the form of generator drag would result in additional gas usage even at idle.
Aug 25th, 2008 (11:57 am)To solve the “long drive followed by mount everest” problem, it might be simpler for the driver to switch to “power” mode from “econo” mode. The tesla has this option. When in econo mode, battery functions as mentioned in the article. While in performance mode, the battery pack is kept full, though not recharged from the ICE. Then it pulls power out whenever those big hills come up. This would be simpler than a GPS system.
Aug 25th, 2008 (11:59 am)#100 Dan – “If the Volt can adjust the generators output, then it only makes sense to use this all the time, rather than to use expensive gasoline to charge the battery and then switch into this more efficient mode. So we can assume the Volt will not be giving the battery a complete charge … ”
The article indicates the gen-set will not be used to recharge the battery pack. So on this point we don’t have to assume anything. However I don’t see anything about several set points, only one. That may be an omission because the question wasn’t asked or it may be that they’ve changed their minds after moving to a larger engine (from 1.0 to 1.4). I’d guess the former but we’ll have to wait for something more definitive.
Aug 25th, 2008 (12:00 pm)As long as we are talking about how things work lets talk about generators too. The Volts generator (all generators for that matter) only require an input load when they are generating current. If you’ve ever used a portable generator have you noticed when you hit it with a load (such as starting up a saw or some other high torque/current starting load) that the motor turning the generator suddenly changes its tune? That is because until you put the load of the saw on it the generator was just freewheeling with almost no load to the motor. Same goes for the Volt. If the batteries are already as charged as the Volt has requested there will be no load (I don’t know how they are switching) on the generator so there will be negligible load on the ICE.
Aug 25th, 2008 (12:04 pm)#105 GXT – “what I am wondering is why the first several dozen posters seem convinced that the generator will no longer charge the battery to 80%. I don’t see that stated anywhere.”
I think they’re looking at statements like these. When looking at the second statement keep in mind that the Customer Depletion Point is the 30% SOC:
“People say the engine comes on to charge the battery, but that’s not what really goes on.”
“So what we’ll do then is we will opportunistically put that energy back into the battery either through regenerative braking or if we have to we will take some of the energy that’s not needed to turn the wheels and bring the battery up to the customer depletion level.”
Aug 25th, 2008 (12:06 pm)customer depletion point = empty
Aug 25th, 2008 (12:28 pm)Sorry, but the chaotic nature of this topic is a great example showing that educational content for Volt is needed.
It’s really hard to have constructive discussions when the basics still aren’t understood. Then there’s the reality that some fundamental questions (like engine RPM) remain a mystery.
If you want to emulate Prius, shouldn’t there be at least the same level of online resources provided? That seems to be a major gap which continues to be overlooked.
Aug 25th, 2008 (12:45 pm)Sorry again if this has already been said, I haven’t read the 111 replies (boy it doesn’t take long these days for Lyle to create a new thread and for the replies/comments to fly in).
For my fellow software engineers, you should recognize the way the Volt handles series hybrid mode is very similar to network transport protocols (TCP in IP land) or queues in either a threaded program or using inter-process communication. You have a supplier (generator) and consumer (electric motor), a queue (battery), and high and low water marks that determine when the supplier comes on and off (30% being the low water mark).
I do hope the Volt allows the user (driver) to tap part of the reserve battery capacity under at least one situation…. when in series hybrid mode (ie. past the “customer depletion point”) the generator runs out of fuel (gasoline)…. so one can make a bee line to the nearest filling station. I think consumers would prefer to take the battery to 20% SoC than to wait for road side assistance (or worse a tow).
Aug 25th, 2008 (12:49 pm)john1701a Says:
“If you want to emulate Prius, shouldn’t there be at least the same level of online resources provided? That seems to be a major gap which continues to be overlooked.”
The Prius is in production, the VOLT is not..
Also, I don’t think GM wants to emulate the Prius in anything besides sales!
~Bob
Aug 25th, 2008 (12:57 pm)>> The Prius is in production, the VOLT is not…
That has absolutely nothing to do with discussions. And isn’t that what was meant by “game changer”, now being in a PROACTIVE mode rather than REACTIVE like in the past? It simply does not make any sense to wait.
Perhaps I should have used the word “dismissed” instead of “overlooked”, because the need for it now should be obvious. Just look at how many times the same questions get asked.
Aug 25th, 2008 (1:01 pm)I have a legitimate question that I want someone to answer:
Why does everyone have an obsession with using the VOLT to carry heavy loads up steep and tall mountains?
If doing this sort of travel is daily for you, perhap it’d be a better idea to get a truck.
Bottom line: The VOLT runs pure electric for about 40 miles. After which it runs on an ICE for 300-400 miles. Any other information (and perhaps even this info.) is disputable until the release of the VOLT in 2011 (read: you’ll have to wait to find out details). Happy waiting!!
Aug 25th, 2008 (1:05 pm)If this doesn’t rechrage the battery, then this car is NOT designed for long distance driving. Hybrid cars should be designed for those people who have long commutes to save on gas.
Paying mid-$30K for a car that won’t save me gas in long commutes is not a wise choice. Might as well get the Prius.
Aug 25th, 2008 (1:12 pm)john1701a Says:
And isn’t that what was meant by “game changer”, now being in a PROACTIVE mode rather than REACTIVE like in the past? It simply does not make any sense to wait.
Perhaps I should have used the word dismissed instead of overlooked, because the need for it now should be obvious. Just look at how many times the same questions get asked.”
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Ahh, I see what you mean. I AGREE! Proactive information would be a boon for GM and their consumers…. but potentially their competitors as well.
Keeping that last part (competitors) in mind, it may still be a bit premature to release said information.
Aug 25th, 2008 (1:15 pm)@117: You think recharging the batteries is going to save you on gas for your long commute? It’s more fuel efficient to run the motor at a lower output level (read: higher MPG) than it is to run the motor harder just so you can show up with a full charge (which you could get for pennies by plugging it at work).
To be clear, it more efficient to run the ICE at a sustainable power output, than it to to create excess power, store that power and then re-use later.
Aug 25th, 2008 (1:17 pm)Albert Landicho Says:
If this doesn’t rechrage the battery, then this car is NOT designed for long distance driving. Hybrid cars should be designed for those people who have long commutes to save on gas.
Paying mid-$30K for a car that won’t save me gas in long commutes is not a wise choice. Might as well get the Prius
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The VOLT is not originally intended for really long drives. BUT, the ICE portion gets 50mpg. It will depend on each potential comsumer whether or not the VOLT is for them.
For me, the battery power is a “range intializer” to a very fuel efficient car. It gets my VOLT…err I mean vote!
Aug 25th, 2008 (1:18 pm)98 DonC………
You’re right that my guess (in post 45) of < 20Hp to propel the Volt on a flat surface at 70 mph is a bit optimistic –your calculated figure of 30-31 Hp is closer. However, my calculation of the additional power needed to climb a steep 6% grade at 70 mph (from post 39, repeated in part here for clarity) is a bit pessimistic*……
Power(Hp) = [F(lbs) x V(mph)]/375 = (4,000lbs x 4.2mph**)/375
= 44.8 Hp (….or 44.8 x 746 = 33.4Kw)
Adding the 31Hp needed to propel the Volt at 70 mph on a flat surface to the additional climbing power of 44.8 Hp needed gives us a total of 75.8HP to climb a 6% grade at 70 mph .
I’m certain GM would be able to obtain substantially more power than is needed from the Volt’s ice/gen to drive its 160 Hp traction (drive) motor, and that the traction motor can easily produce more than this calculated output power (76 Hp) at the front wheels.
ATTN GM: However, the ice/gen, control electronics & traction motor MUST be upgraded to operate continuously at these power levels without overheating. If this upgrading is achieved, the Volt should be able to climb a 6% incline to a height of 10,000 feet with NO (or very limited) assistance from its battery.
*Pessimistic because it assumes there are NO milder grades than 6% (and no downhill sections) during the entire 10,000ft climb
Aug 25th, 2008 (1:18 pm)One thing is for sure. If GM is reading these post, they will certainly agree that we have some big questions that need answering. I just hope GM is answering them properly. I don’t expect them to come out and answer them publicly, but when the Volt is released for review by vehicle testers for major publications we will finally see some answers. Maybe we will like the answers and maybe we won’t, but we will know the answers finally.
There are some really fine questions and answers on this post. Just the answers are not from GM and official. I would imagine at this point the answers are for questions that are still be derived.
Aug 25th, 2008 (1:21 pm)I think some of us missed the paragraphs in which the GM guy stated that the ICE will in fact charge the battery, his emphasis on the regenerative braking made it easy to miss. He stated…
“And then when you take your foot off the gas, as an example when you’re done doing the merge, we had taken a little bit out and the battery has a little less in it. So what we’ll do then is we will opportunistically put that energy back into the battery either through regenerative braking or if we have to we will take some of the energy that’s not needed to turn the wheels and bring the battery up to the customer depletion level.
So we don’t recharge the battery. The customer wont actually see any of this, as their electric range indicator in the car will only say zero.”
John1701 is right, a lot of us haven’t gotten the FAQs down yet and are making this more complicated than it has to be. This is going to be a great car if they deliver what they say they will deliver, and all of the, “it doesn’t seat 5, I hate it”, or the “I have to be able to drive to Pikes Peak and then climb it at 70 mph” are missing the point. (And we may be able to drive 200 miles and still climb a long rise if the state of charge is arranged properly)
We need to be able to buy cars that allow us to use vastly less petroleum/gasoline. The Volt will be able to do this nearly seamlessly. There may need to be mechanisms to allow an over-ride of the usual battery only power til 35% state of charge is reached, (i.e. a command to start ICE function at 50% instead, or 60% if needed) but that is a tiny problem to be addressed compared to building a 16KWh battery that will last 150,000 miles at a reasonable price and still have it be small enough and light enough to make the Volt a pleasure to drive.
Aug 25th, 2008 (1:24 pm)#69 Voltme Says: “This begs the question, “If you have a propulsion system in which a small efficient gasoline engine powers an onboard generator which in turn supplies electrical energy to an electric motor to propel the car at 50 mpg, why would you not employ this system as a mainline powerplant without the expensive batteries?”
The key is the word efficient. A 1.4L single RPM ICE with peaks smoothed by a small battery is much more efficient than a typical car engine, even a compact car engine. So you could put in a much smaller battery than currently envisioned, and reduce cost and weight. You would have a cheaper car that instead of 50 MPG gets to a slightly higher number, say 52-55 (just guessing). Sort of a slightly more efficient Prius, but not a 150 MPG game changer.
The justification for E-Flex is that the ICE is still much less efficient than an electric motor powered by current from the grid, and stored in a big battery that enables 40 miles with the ICE off. It is that 40 miles on 80 cents worth of electricity, which might be 80% of all miles driven for a majority of consumers, that justifies the big expensive battery.
Aug 25th, 2008 (1:26 pm)#19 LyleL
“Oh my heart be still…. the posted pic is an EV1 dash!
It’s cool to see the power up sequence.”
I am glad someone answered my wondering to myself about the included picture with this post. I was hoping it had nothing to do with the Volt. I looked kinda of “old fashion” to me. Sorry, LyleL if I hurt your feelings, but I a glad you gave us the link. “My Last Ride” was a nice video to watch. Thanks.
Dr. Lyle: Anyway to place a picture’s descriptive text below photos you place on the site. That could be interesting and remove questions about just what the picture is. Maybe even a link to the picture’s source if text can not be added.
Aug 25th, 2008 (1:29 pm)After all is said and done, if the Volt can’t climb long hills any better than my 1996 Ford 460 V8 powered motorhome (truck lane, engine screaming, 17 miles per hour), it’s going to be a huge disappointment for far more than 1 percent of the owner base. If this problem isn’t addressed, the vehicle will be pigeon-holed by the general public as yet another tree hugger, carbon neutral, minimal footprint piece of ecological garbage instead of a serious alternative passenger vehicle for the masses. I want to buy one vehicle for ALL of my transportation needs just like I can do today. If the Volt can’t offer this, it’s not a player!
Aug 25th, 2008 (1:36 pm)ANDREW FARAH says:
“But when the engine comes on to spin the generator, it does so with the idea that we’re generating electric energy to drive the wheels, not to charge the battery.”
Thanks Andrew now half the community thinks the ICE engine is connected directly to the wheels. I know your an engineer but damn, how about something everyone can understand.
For clarification i’m pretty sure what he meant was:
But when the engine comes on to spin the generator, its software is designed to drive the wheels, not to charge the battery.
John1701a:
Why or who would put out educational materials for something that isn’t finalized or from a consumer standpoint dosen’t exsist. So 1/2 the guys here could read it then in six months say “but the brochure said……..” . I’m not buying one, GM lied to us!!”
Aug 25th, 2008 (1:42 pm)That clears up some uncertainty that I’ve had. I have read that the Volt’s IC engine always just charges the battery and the battery then feeds the electric motor and the wheels turn, etc. I’ve also read that after 40 miles, the IC engine creates electricity directly via the generator … which then feeds the electric motor and the wheels turn, etc.
I was wondering which one was correct. Either way, as long as the IC engine can run on E85 (other liquid fuels maybe) and is getting the equivalent of 50+ mpg while it’s making electricity for the generator to pass to the electric motor, that’s fine with me.
From what Andrew Farah is saying, the IC engine just turns the generator brushes to make electricity. The electricity generated either goes straight to the electric motor to turn the wheels or some of it goes to the battery to bring it back up to 30% SOC.
I bet GM has plenty of work to do with programming the Volt’s control systems for all the scenarios it might run into. Things like steep hills and people that are constantly flooring the accelerator for whatever reason. It makes me wonder if and when they are going to add ultracapacitors to the Volt or a future E-flex vehicle. Integrating ultracaps into the system might be better than using that last 30% of the Li-ion battery to use for acceleration, hill climbing, etc. GM better make sure they test the Volt in all sorts of real world situations.
Aug 25th, 2008 (1:44 pm)# 60 Tom Harwick
I think, that „energy intensive mode“or “mountain mode” should not mean 80 % charge. Should be enough 50 % or even 40% when engine kicks in. 5 mile 6% grade is very exceptional case and can be handled by IEC when in the end of elevation little bit slowing car. In case you keep 80% charged battery there will be no room for regenerative braking on downhill. Let’s assume that normal driving capacity on highway is 12 kW (60 mph). I think on the slope average IEC load will be not more than 35 kW. Very short load increase can be when accelerating on the slop uphill and will be handled by the 40% battery reserve.
Thanks for commenting on my post. I think your point is a good one. There is a lot of opportunity for refining the logic here. A lot of questions can be asked, and answered (due to the complexity, it will probably require GM engineers who are actually getting paid, to tease out the most refined solution)
1. What do you want to use as the worst grade you want to be able to handle (even this question is simplistic, because real world roads have complex shapes like a roller coaster, not a simple inclined plane)?
2. What would be Volt performance with a depleted battery? Again, the question is more complex. Are we talking steady pull? Speeding up after slowing for a yield sign? Starting-up after a full stop?
3. Does marketing think it is OK to simply live with that performance?
4. If we set a higher performance baseline than the ICE alone can support, what would be the draw on the battery in kW, needed to maintain that performance on the type of hill that would be our reference?
4. What percentage of US roadways would present conditions no worse that our reference? 99%, 99.99%?
5. How long would we have to maintain reference performance in reference conditions? In other words, are we talking a 24 mile trip over the smokies at an average 4% grade, with a stop every 6 miles, and no passing allowed?. Are we talking a 12mile trip and an average 5.5% grade with no stopping, but the need to pass? Again, the question is more complex than this, see 1 and 2 above.
6. If you had the answer to all these questions, you could calculate your upper set point in “build reserve power” mode.
I would not be shocked to find that number lower than 80% SOC, as you suggest.
Since the setpoint would be stored in the software, it could be user selectable. The downside of that of course, is if you are making a lot of long trips, but not usually crossing mountains, a high set point will waste a lot of gas, which could alienate drivers who would not realize their own choice of setpoint was the culprit. (Once again, you could quantify how much gas you would waste under what conditions. If you charge up to 80% every time you significantly exceed a 40 mile trip, but only do this a couple of times a month, who cares?)
Aug 25th, 2008 (1:48 pm)There are too many conversations here based solely on the info from the referenced interview. Some need to go back and read the history of the gen set development, and many of these questions become clearer.
The 2 biggest still unclarified questions are:
1) Will the ICE run at constant RPM or not?
2) Will the generator have variable output levels or not?
Answer these questions and most of the other issues discussed here will fall in line based on common sense. Without answers to these questions, this discussion has no compass.
Aug 25th, 2008 (1:51 pm)Belloc Says:
August 25th, 2008 at 10:15 am
If I wanted a pure EV with a 68 mile range could I just run without gasoline?
If this is answered above, please disregard, but the answer is no. You would pass your 30% SOC setpoint, and shorten your battery’s life significantly, and lose more money than you would have spent by just buying some gas.
But you would indeed have a 40 mile range BEV.
Some drivers will do this.
But if GM or somebody else builds a VOLT-class BEV, they will be able to sell it for cheaper than the VOLT, because it will not have an ICE.
Aug 25th, 2008 (1:54 pm)#124 Tom:
We are saying the same thing I believe. I’m not saying let’s dump the Volt and instead rip out the E-Flex sans batteries and start producing cars this way. What I’m saying is, alongside the Volt, you can use the same tech (sans most of the batteries) to create a very efficient powerplant which can be made and sold at a reasonable price point and can compete with other fuel efficient cars and hybrids.
So, for example, you can have a Volt at $35k (with Li-ion and 40 miles AER) and you can also have a Malibu LTZ with e-flex powertrain (sans Lithium ion batteries) that gets 50+ mpg for around $25k.
If this proves to be possible, I can see “e-flex gas-electric” powertrain supplanting ICE in most all GM cars, trucks and SUVs.
Aug 25th, 2008 (1:56 pm)#37 CDavis
I appreciate your point. The death of a child or children is a great tragedy that affects not only the family of the child or children but many of us who read about it.
I would like to offer another solution. When a car is parked with the engine off or on and the car detects weight over a small limit and heat builds up to over 80 degrees (or some other degree) the car could sound the horn as in alarm mode and if equipped with electric windows could lower the windows by a few inches. The horn should continue to blow until a door is opened. The system then should reset itself and wait for the next time. The car could even be programmed that if that happens two times, the car could refuse to operate, except for doors being allowed to open and windows up/down. The engine/drive train could refuse to go into gear.
Just my thinking on this subject.
Aug 25th, 2008 (1:57 pm)#john1701a
I think it’s just most people have difficulty grasping the information given, just based on how it’s organized (basically not organized at all, you have to dig through the articles). If someone writes a simple wiki page it might help. But people are discussing some very specific details on a car that isn’t even in production yet. I doubt any of this is concrete, given they are still tweaking it, and as such GM can’t really give very specific information yet (you can see how they had to make clarifications etc).
Aug 25th, 2008 (2:06 pm)#130 Meterology First
“The 2 biggest still unclarified questions are:”
1) Will the ICE run at constant RPM or not?
I thought this was discussed at Volt Nation & GM has already said there will be multiple (2 or 3) set rpm levels.
2) Will the generator have variable output levels or not?
Isn’t this the same thing, if the ice runs at a lower RPM dosen’t the generator produce less power.
Jon
Aug 25th, 2008 (2:10 pm)#132 Voltme Says:
What I’m saying is, alongside the Volt, you can use the same tech (sans most of the batteries) to create a very efficient powerplant which can be made and sold at a reasonable price point and can compete with other fuel efficient cars and hybrids.
So, for example, you can have a Volt at $35k and you can have a Malibu LTZ with e-flex powertrain (sans Lithium ion batteries) that gets 50+ mpg for around $25k
———————————————————————-
This sounds like a good idea. Many consumers who go less than 40 miles a day would still get the VOLT however. If a difference in price is that much (ie only the battery) then I would expect to see many buyers… But I believe GM will NOT do this until the 2012 model year at least… but who knows?!
~Bob
Aug 25th, 2008 (2:16 pm)Lyle,
I appreciate all of your effort and the information you provide and this is in no way a criticism. But this post is just the tip of the iceberg of how the whole ICE and regenerative braking algorithm works. There are lots of unanswered questions about how the ICE and regen control works. All of the what-ifs.
As has been stated earlier in this thread. What if you are approaching the Rockies out of Denver and you are down to “customer depletion point”, i.e. ICE is sustaining the power required to turn the wheels and power accessories, will you eventually be traveling only with the max output power of the generator? If so, it will be a slow pull up the Rockies.
As someone suggested in another thread or in the Forum, it would seem desirable to have a mode where you could anticipate the need for more power and manually override the charging algorithm and the get the battery up to the 80% level prior to hitting the Rockies accent.
Also I don’t think we yet know definitely whether the ICE runs at only one RPM rate or not, whether it comes on and off as you drive, whether it turns off in stop and go traffic, etc. There have been contradictory statements made about the running of ICE.
Lyle, if GM would give us a more complete description of how the whole ICE and regen charging algorithm works then GM would get better feedback. Of course for completive reasons GM may not want that kind of information public.
Aug 25th, 2008 (2:33 pm)Informative.
Tag
Aug 25th, 2008 (2:40 pm)>> Why or who would put out educational materials for something that isn’t finalized or from a consumer standpoint dosen’t exsist.
There is no need for finalized specs. That level of detail is totally unnecessary. The (now rather obvious) need is for a basic understanding of the concept itself. Just highlights of what happens when would make a world of difference.
I strongly suggest you study both the history of HSD, IMA, and Two-Mode for the why. As for the who, there are plenty of enthusiasts here that could easily contribute to the editing of information text.
Aug 25th, 2008 (2:45 pm)Run the Volt until it reaches the “customer depletion point” then drive it up Pikes Peak under full power. If it completes the climb with no loss of performance and nothing heats up, then the car is ready.
Aug 25th, 2008 (2:51 pm)#121 nasaman
I didn’t look at your calc the first time but why are you using .06 for the vertical component of the velocity? Wouldn’t the sine of six degrees be more like .104528 (from my calculator obviously)?
If you use .1045 for the sine rather than the .06 (small angle approximation?) I get something in the range of 56 kW. If I use it in your shortcut equation (I know it’s right but I can’t get used to HP or pounds) I get 78 hp.
Or am I messed up?
Aug 25th, 2008 (3:12 pm)#85 DonC
“The possibility also exists that someone like Statik would be doing 90 mph with jackrabbit starts, discharging at over 1C. In these cases you are looking at 7000 cycles, with potentially some of the discharges above 1C. ”
Hey!
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/I prefer doing ‘bootlegger’ turns I’ll have you know
Aug 25th, 2008 (3:17 pm)I seem to be one of those mountain type people, but am also in the category of never wanting to use gas if I can.
I live in Fort Collins Colorado (60 miles north of Denver and at the base of the mountains). I also commute to work with <25 mile round trip each day.
For my primary driving to/from work, the Volt is perfect. I might never need to use gas again!
Since I do go skiing quite a bit in the Colorado mountains, I am also in what looks like the worst case “Customer Depletion” situation too. I will drive the Volt 60 miles on a relatively flat interstate highway to Denver and then head up into the mountains for another 60 miles or so, generally all up hill, much at 6%. I did this trip many times in a very underpowered diesel Rabbit and would rather not have the unpleasant issue of having to pull over to the shoulder to barely slog up the hill again.
I am a proponent of a selectable mechanism of choosing when and how long the ICE kicks in. Most of the time, I NEVER want the ICE to come on since I will recharge at home. Heading to the mountains, I would like to have the ICE come on and “top off” the battery while I am on the flat to have enough additional boost to get up the mountains at a resonable rate of speed.
I guess the only solution is for Chevy to give me an early Volt so I can try out this scenario for them. Just like everyone else on this board wants.
Aug 25th, 2008 (3:30 pm)It would be interesting if GM would select a group of educated, experienced people (some of you in this group) as a study group where some Volt operational information could be given to them to analyze and report back with responses and questions. It would need to be done on a secret confidential basis with each person agreeing not to divulge any information given to or from the group. This group could be a good place to get outside feedback on the internal operations of the Volt. As a software designer/programmer, I know from past experience you can develop a wonderful “system” in a closed environment, but once released to the “public” a few holes appear. Well, just take a look at most computer operating systems for an example of “holes”.
Just my thoughts.
Aug 25th, 2008 (3:46 pm)Right N. Riley #144, I work in a similar environment as you . I agree there is nothing like a field experiment in real conditions with real educated users in real situations.
Aug 25th, 2008 (3:47 pm)N. Riley@144
I’d share my thoughts on that, but then I’d have to kill you (just kidding). I know GM has been doing “focus groups”. How would that differ from what you suggest?
Be well,
Tag
Aug 25th, 2008 (4:05 pm)Many people are worried about the ability to haul butt on a long trip in the hills or mountains.
Most people who buy this car will never drive it that way, This is the ultimate commuter car, not a highway machine.
We have a 2006 Pontiac Vibe, 1.8L. Toyota engine with 125 h.p. It is an awesome commuter car but it is NOT the best highway car. We took it out west from Illinois to Lake Havasu AZ (on I-40). There were several times I had it to the floor on long climbs to maintain 70 mph and that was all it could do.
I can live with that knowing I got 34 mpg for the whole trip driving 75 to 80 mph most of the time. If the VOLT driver has to crawl up the last 1000 ft of a mountain range at low speed, big deal. I’m a horse power freek but for the gas you save during the whole trip, who cares if you have to slow down up a mountain pass here and there. Big trucks do it all the time.
I am curious if the generator is A.C. or D.C. A.C. generators run at a constant speed, usually 3600 rpm. or 1800 rpm, both of which are multiples of 60 so you can get 60hz. electricity, (at least for household use). If it is an A.C. generator it will likely be a constant speed engine. D.C. generators are a different story.
Aug 25th, 2008 (4:08 pm)Voltme #132
I’ve been a big proponent of the “less is more” theory regarding the Volt’s battery size and cost. At a cost of $650 per Kwh, I believe GM should consider reducing the Volt’s battery size or eliminating it all together.
Futhermore, by equipping other vehicles (Aveo/Astra/Cruze/Colorado) with pure gas/electric powertrains, GM would provide an affordable quasi E-Flex solution for the masses.
Aug 25th, 2008 (4:15 pm)I live in CO and I desperately want to be the first person to drive the Chevy Volt up Pikes Peak!!! If the Volt make it, It will be a huge feather in the GM Engineering group’s cap.
Aug 25th, 2008 (4:22 pm)No Battery People:
The Volt will not work without a battery pack. The generator is not large enough to completely power the car. It is only about half the size of the electric motor that drives the wheels. It needs the battery as a buffer for quick bursts of power, or to help with going up a hill, etc.
Also, the whole idea of this car is to have some all electric range, powered by a battery pack that is charged from the grid. That is where the real fuel saving are going to come from.
To put in a larger generator that would power the car in all situations would require a larger ICE to spin it. Then the mileage would go down. Why have a gas based engine spin a generator to power an electric motor? It would be better just to have the ICE turn the wheels! Oh wait, that is what we already have…………
Tag:
A focus group is just there to give opinions of ideas from the company. It is usually done very early in the process. What Jean and N. Riley are talking about is more like the Project Driveway, where actual vehicles are put on the road and tested in real world situations by people who then report back the problems that can be fixed before the full scale production runs are started. In the computer world, they are called Beta Testers.
Does that help any?
Aug 25th, 2008 (4:22 pm)Plug Free Volt
Sorry, but your handle is an oxymoron. A Volt without a plug, is no longer a Volt.
Be well,
Tag
Aug 25th, 2008 (4:27 pm)#133 … some sort of protective mode if the car reaches 80 deg F with extra weight inside?
Seems like a bit of a severe penalty for leaving luggage in the car when you stop at a diner for lunch.
-dk
Aug 25th, 2008 (4:28 pm)Jim I@150
Said:
Tag:
A focus group is just there to give opinions of ideas from the company. It is usually done very early in the process. What Jean and N. Riley are talking about is more like the Project Driveway, where actual vehicles are put on the road and tested in real world situations by people who then report back the problems that can be fixed before the full scale production runs are started. In the computer world, they are called Beta Testers.
Does that help any?
I thought that that was the “prototype program”. I guess a rose by any other name…..
Be well,
Tag
Aug 25th, 2008 (4:31 pm)If the ICE operates at 4 states, it might be (1) OFF, (2) low RPM/8KW generator output, (3) Mid RPM/24 KW generator output, and (4) High RPM/48 KW generator output. So if the SOC is above 35%, the ICE is OFF, if the SOC is between 35 and 32 %, the ICE/generator produces 8 KW, roughly equal to low speed urban driving. If the SOC falls below 32, the ICE/generator increases power output to 24 KW, roughly equal to high speed highway driving, plus extra to raise the SOC back to above 32%. And if, due to a sustained grade at high speed, the SOC would drop below 29%, the ICE would go to high power mode, producing 48 KW to cover high power usage plus enough to recharge the battery back above 29%.
While the numbers will be somewhat different, this seems to reflect the apparent operational strategy envisioned early on. Shucks, my crystal ball just fogged over.
Aug 25th, 2008 (4:32 pm)#146 Tagament
I just couldn’t think of the words “focus group”, I guess. The real difference is their focus groups are apparently designed to give feed-back about the looks of the car. I am talking about giving this focus group a much broader amount of information about operational aspects of the Volt to get feed-back. Many of the questions posed by members of this forum could be discussed with GM as part of this focus group with GM providing their current solution and the focus group analyzing it and questioning GM’s solution, if necessary. How better to determine short comings than having an educated, experienced focus group look under the covers of the Volt. In full confidence with GM.
Aug 25th, 2008 (4:37 pm)N. Riley@155
That’s pretty much how I pictured the role of the lucky ones who are chosen to drive the prototypes for several months (waves hand wildly). Much of the real world feedback would be automatically provided through Onstar.
Be well,
Tag
Aug 25th, 2008 (4:39 pm)Tag:
Prototypes would be more like the mules they are running now, and the next almost complete testing vehicles would be the Alpha Testing cars. Then the Beta testers, then full production!
Fun, isn’t it????
Aug 25th, 2008 (4:40 pm)stopcrazypp Says:
“I think it’s just most people have difficulty grasping the information given, just based on how it’s organized (basically not organized at all, you have to dig through the articles). If someone writes a simple wiki page it might help.”
Already been done:
http://en.wikipedia.org/wiki/Chevrolet_Volt
Aug 25th, 2008 (4:42 pm)#150 Jim I
I am not especially talking about a “project Driveway” type of group. That would be great, also. I primarily mean for GM to give this group technical information about the operational aspects of the Volt. Let the group study this information, consulting together in meetings with the other members of the group and maybe GM at some point. The group could determine feasibility in real world terms of what GM is proposing with the Volt and suggest changes to those decisions based on their eduction and experience and discussions with GM personnel.
If they could drive a Volt-like car during some of the meetings to help clarify GM’s position and better understand the Volt, that would be great. More eyes on the project with panel discussions, etc just seems like it would be helpful.
All of us have had so many questions that we don’t have answers to and we don’t know if those questions have been or will be answered by GM. This focus group could work to understand and give GM some experienced guidelines outside their “ivory tower” mentality.
It is probably too late in the “game” for GM to receive the benefit of a focus group like I envisioned. Should have done this early this year.
Aug 25th, 2008 (4:42 pm)It would be really cool if GM used a few of us here from GM-Volt.com as Beta Testers!
Of course, on the day I was supposed to turn it in, there might be a malfunction of the On-Star, and the car may never be seen again……….
HAHAHAHAHAHA!
Aug 25th, 2008 (4:43 pm)OK all of you long term visitors here. Pick up where I fall off. There are a lot of new people here asking questions or making statements that show they aren’t up to speed on how the Volt works. No problem. But I just can’t get over all the people here that have been regular posters that have no idea what they are talking about.
For Long term members!!!
Doesn’t everyone here know the battery will be discharged down to 35%?
Doesn’t everyone here know the battery will use 50% of the batteries potential charge!
Doesn’t everyone know that the ICE will power the electric motor.
Now I see what kind of an uphill battle GM has in getting the facts out to the public. Please read the post and not just look at the pictures!!!
Aug 25th, 2008 (4:48 pm)141 DonC…..
Grades are expressed in percentages, not degrees (6% is the steepest grade normally allowed on US highways).
Aug 25th, 2008 (4:51 pm)#105 GXT Says: “… what I am wondering is why the first several dozen posters seem convinced that the generator will no longer charge the battery to 80%. I don’t see that stated anywhere.”
————————————————————————————–
It was stated last summer:
http://gm-volt.com/2007/08/29/latest-chevy-volt-battery-pack-and-generator-details-and-clarifications/
nad has been restated several times since.
Aug 25th, 2008 (4:52 pm)Oh, here’s something extra to chew on about going up mountains.
When actually traveling up the mountain in a car with a normally aspirated engine, you lose horsepower due to the change in air density. The air density will be around 31% less dense at 3km in altitude vs. sea level, so you will lose at least that amount of HP (almost certainly more, since I would imagine there are intake related losses which would subtract from pressure in a more or less constant amount). At a more frequently likely 1km, you’d lose about 11% of your air density. I should also mention that this is not my engineering specialty. I worked through the equations here:
http://wahiduddin.net/calc/density_altitude.htm
So, if I worked my numbers right, that is about 3% loss of air density per thousand feet in elevation. I’m guessing that’s more like 4-5% loss in HP per thousand feet in elevation change, but I’m not really sure on that. That would be my “intuitive” guess from driving normally aspirated cars up mountains, anyway. Looks like the air density measurements at confirm most of that guess, but it’s still pretty rough.
Which is why I was disappointed that they switched from the turbo engine. I acutally do drive up to or through the moutains several times a year and the turbos nearly eliminate any altitude air density issues.
Of course, the turbo gets a real working running constantly but to quote Conan the Barbarian, what doesn’t make you crack and fly apart makes you stronger.
Also, I wanted to say, I’m glad to finally hear the SOP for the CDP. I won’t be able to win at Technobabble Bingo without some more TLAs.
Aug 25th, 2008 (4:54 pm)N Riley #158:
The only problem is that there are 40K people here with 40K different ideas of what they want this car to be!
I want no batteries.
I want more batteries and no ICE
I want 0-60 in 5.5 sec.
I want no frills
I want all frills
I want 4 seats
I want 5 seats
Etc, Etc, Etc.
No matter what they produce, there are going to be people that are angry or disappointed in the vehicle. If they could produce “one” magic car that satisfied everyone, then all the other manufacturers might as well close up shop. Does anyone think that is going to happen?
Passing some concepts around to open forums is a good idea, but they are getting awfully close to production to be starting that now for the Volt Gen-1, don’t you think?
It is time to finalize the complete design and get on to government compliance testing, beta testing, and then production. 26 months might sound like a long time, but for a project of this size and complexity, it isn’t…………
JMHO
Aug 25th, 2008 (5:02 pm)omegaman66 #160:
I agree with what you are saying, but on the other hand, we have been given some very conflicting information from different people at GM. I can see now why manufacturers keep quiet as long as they can…. Maybe it would be better if GM appointed a singe person or a small group of techs to release real and accurate information to us. Then we could all stop trying to read the battery range of the car, based on the color of Mr. Lut’z tie or the color of a test battery pack from a picture when he makes a statement to the press!!!!
Aug 25th, 2008 (5:05 pm)Jim I@164
…It is time to finalize the complete design and get on to government compliance testing, beta testing, and then production. 26 months might sound like a long time, but for a project of this size and complexity, it isn’t…………
JMHO
Gee, I wonder what phrase just pops to mind….. Oh yeah.
“LET’S JUST GET THE VOLT’S WHEELS ON THE ROAD!!!!”
Aug 25th, 2008 (5:06 pm)#130 MetrologyFirst Says: “The 2 biggest still unclarified questions are:
1) Will the ICE run at constant RPM or not?
2) Will the generator have variable output levels or not?”
————————————————————————————–
For #1, no one really knows. There is conflicting information.
For #2, the answer is yes, the ICE / generator will have variable output. If the ICE is variable RPM, then this is obvious. If the ICE is constant RPM, the output still varies. If the load gets heavier, the controller adjusts the fuel/air mixture to increase power while maintaining the same RPM, otherwise RPMs would decrease. When the load is light, a constant RPM engine is running mostly on air.
So either way, the ICE / genset has variable output.
Aug 25th, 2008 (5:16 pm)#148 Plug Free Volt
I’m not advocating a plug free Volt and I’m not advocating reducing the number of batteries on the Volt. I’m pro Volt and pro plug-in.
My idea is to speculate on a spin off vehicle(s) using the Volt’s gas-electric tech (sans battery) powertrain which would get 50+ mpg.
In this scenario, GM would use the ICE+generator+electric motor with a 3-5Kwh battery which would be used as a “peak buffer” when needed and otherwise kept at peak capacity via regen or generator feed.
This powertrain would be fitted to Malibu’s and Cruzes first then later in most all current ICE vehicles.
The tech could also be sold to other manufacturers to offset GM’s production cost.
As an additional means of offsetting all this cost that’s going into this vehicle, I also expect them to begin selling Volt RC and scale die-cast models as soon as the production model is unveiled (likely on Sept 16th). I had a recent conversation on this topic with a very highly placed source at GM where it was revealed that a past model (Sierra XR-4 from Ford Europe) had higher margins for the RC version than the actual production vehicle! I believe the chances are quite good that you will be able to buy a Volt RC this Christmas…
Aug 25th, 2008 (5:25 pm)Good, so I can depend on getting home with a 30% charge and then top it off with home’s current.
I think I’d still like to remove the ICE.
How about that mod?
Aug 25th, 2008 (5:32 pm)Is it just me, or is anyone else hanging for some real, honest-to-goodness news?
Seems like we are experiencing the summer blahs here at GM-Volt.com.
Aug 25th, 2008 (5:37 pm)“Customer Depletion Point” ???!!!
Really. The GM guy who makes up these phrases really needs to think about it longer. The ‘Customers’ are not depleting, the ‘charge’ is depleting. How about “Minimum Charge Point” = “MCP” – or – “EREV Startup Point” = “ESP” …?
C’mon guys! This little acronym will come back to bite you in the car magazine reviews just like the name “Impact” that you hung on the EV-1.
Think, guys. Think!!!!
Aug 25th, 2008 (5:54 pm)#171 Gordon:
Ha ha, yeah. “Customer Depletion Point” sounds like it ought to instead refer to some MSRP retail price level.
Some price point at which either customers run out of money (the sadly Cash Depleted Customer) or at which GM has few customers available (kind of like a depleted (of electrons) diode region). Either way, it would apply.
Aug 25th, 2008 (6:09 pm)If GM is looking for someone to test one of there volts in early 2010 in an area with extreme weather changes and mountain climbs I would be glad to help them out as I live in Denver,CO.
Aug 25th, 2008 (6:14 pm)The “customer depletion point” sounds to me like the point at which the customer finally runs out of patience.
Something a little less confusing is required I think..
Aug 25th, 2008 (6:20 pm)Statik@170
Said:
Is it just me, or is anyone else hanging for some real, honest-to-goodness news?
Seems like we are experiencing the summer blahs here at GM-Volt.com.
Yeah, it’s just you. (wink).
I’m still sitting here wondering why so many people want to change the Volt significantly before it’s even seen the light of day (publicly). Sigh. Of course, SOME would say that it’ll never SEE the light of day…..
Be well,
Tag
Aug 25th, 2008 (6:38 pm)Some (but not all) in this thread have a misconception about the relationship between power,whether measured in horsepower (hp) or kilowatts (kw) and engine rotational speed. It is not necessarily true that you get more power the faster the engine rotates.
To give a hypothetical example, an engine turning at 1800RPM may be putting out very little power if it’s spinning without a significant load. Add load, and, to keep the engine at 1800 RPM, more fuel will be needed, and the engine will be putting out more power. So, an engine turning at 1800 RPM may be able to produce any amount of power from close to zero up to it’s design maximum at that rotational speed. So, the Volt gas engine could theoretically be designed to operate at one optimal rotational speed and put out whatever power is required for the load (which for the gas engine is the electrical generator!).
But it’s more likely, as stated above in a few different ways, that there will be a few rotational speeds (or it might even vary continuously over an optimal range), to optimize fuel consumption vs. power requirements for different driving conditions.
Now, here’s the more interesting part. An electrical generator works the same way. Without getting into the details of how it works (I’ll leave that to Nasaman!), you can keep the generator operating at 1800 RPM (or whatever), and put out just enough electrical power (kw) to match the car’s electrical load. In the Volt, that will be done by careful matching of fuel fed to the gas engine (which in turn drives the electrical generator) with all the simultaneous electrical loads on the electrical generator (e.g. battery charging, car propelling, air conditioning, radio, windshield washing)
The control system needs to be pretty sophisticated. I’d love to get the algorithm, but I doubt that GM will talk about it much. I’ve been trying to get that info for Toyota’s Hybrid Synergy Drive, which has to solve very similar control problems, but without much luck. Anybody have any suggestions? All I can find is a lot of info about the power splitter (quite an interesting device!).
Here’s a hypothetical example for the Volt: Gas engine at 1800RPM, car at 60MPH on flat road. Driver hits a hill. Car slows down, but gas engine is maintained at 1800 RPM by the control system varying the fuel input accordingly. Driver presses accelerator to maintain 60MPH. The control system sends more current (or maybe higher voltage?) to the electrical motor driving the wheels. This slows down the electrically connected generator and its mechanically connected gas engine. The control system opens the gas engine throttle more, feeding more fuel to get the gas engine (and its mechanically connected electrical generator) back to 1800 RPM, which will produce more electrical current at the new load. So, now you are going 60MPH again, and the engine and generator are still turning at 1800RPM, but matching a different load. And you are using more gas and going uphill.
I think that the Volt will feel pretty much like a regular car (even up long grades) … minus the gear shifting … and the sounds it makes might be quite different!
Aug 25th, 2008 (6:58 pm)With all the posts about Denver, don’t forget where most of the Volts will be sold in the first year. Some Southern California drivers commute up the Cajon Pass each day. Starting at about 1070 feet, the road rises to 4190 feet in about 13 miles of high speed freeway driving. Add air conditioning in summer, heat during winter snows and headlights at night. The pass is used for travel to Las Vegas too. For those who enjoyed an EV-1, how fast did the car travel up the pass? This report from 1998 doesn’t give the speed details, but does indicate the charging frustrations on a longer trip.
http://www.zefiro.com/ev/vegas/evvegas.txt
Even with the older batteries the car made it up the mountain with no complaints from the driver. Way to go GM!
Aug 25th, 2008 (7:16 pm)Did anyone bring up the fact that what they are saying now goes against the furnace-like charging graph they showed a few months ago? In that charging situation the ICE came on when it got to the low setpoint and turned off when it got to the high setpoint. So which is it?
GM, please answer the following (if you want to of course):
1) Is the generator directly connected to the motor in such a way that the battery can be completely disconnected?
2) If there are two different paths to power the motor how do they work together?
Thank you for the clarification.
Aug 25th, 2008 (7:28 pm)Texas think this doesn’t conflict other stating the OLD 30% SOC level instead of the latest 35%-85% range. This article doesn’t conflict I don’t think but just doesn’t address what happens when the SOC happens to go up enough for the ICE to turn off.
“So what we’ll do then is we will opportunistically put that energy back into the battery either through regenerative braking or if we have to we will take some of the energy that’s not needed to turn the wheels and bring the battery up to the customer depletion level.”
This means to me that the ICE will use it variable range to match the demand most of the time. Only occasionally will it generate more (coasting or stopped) and only occasionally will it not generate enough.
Aug 25th, 2008 (7:41 pm)#172, #173, #175 Gordon, Dave P, bruce g
Here’s another way to think about it —
At the customer depletion point, the customer, being depleted, pulls off into a rest station, plugs in her car, uses the facilities, gets some snacks and has a nice picnic. In an hour or so the customer, no longer depleted, returns to the car. At this point, through the minor miracle of recharge, the car runs much better
Customer depletion can be handled even more satisfactorily if the depleted customer is able to pull into a shopping center and recharge herself and the car there too.
(smile) This terminology is so weird it is going to inspire this sort of thing forever.
Aug 25th, 2008 (7:46 pm)#162 nasaman
Of course! Many thanks.
Aug 25th, 2008 (8:40 pm)Geeeezzzzz It never ceases to amaze me on how much is read into or out of a simple statement. I do believe that if a GM represenative were to state that the sun will shine tomorrow that there would be those who would argue for cloud cover.
Give it a break people and quit trying to see a boogyman around every corner.
Aug 25th, 2008 (9:30 pm)I have 2 hopes:
1. That GM replaces “customer” with “battery” in “customer depletion point” before Nov. 2010.
2. That the ice stop (or slow way down) when the car is at idle, or in slow traffic. This will, however, bring in heat issues, as the pollution systems need to be kept above a certain temperature.
Aug 25th, 2008 (9:35 pm)George K@184
If I read it correctly in the chat, Bob Bonaface said that the Volt will shut down when stopped, including stop-and-go traffic.
Be well,
Tag
Aug 25th, 2008 (10:52 pm)Wait till the EPROM chippers get ahold of this car. You will probably have all sorts of choices of how / when to run what in whatever stated of charge.
Aug 25th, 2008 (11:29 pm)177, Steve…….
An excellent explanation, Steve! I strongly suggest everyone still confused about this subject carefully re-read your post #177!!!
Just as a conventional car’s battery is connected to its battery thru its voltage regulator, the Volt’s ice/gen will NOT be connected directly either to the Volt battery OR to the traction motor. In other words, a normal car’s battery charge is controlled electronically (the alternator has no load on it when the battery isn’t being charged), and the Volt’s ice/gen power (whether steered to the traction motor, to the battery, or to both by the control electronics) is able to have its load fully connected, partially connected, or fully disconnected electronically. So the ice/gen could be “spinning unloaded” while consuming almost no fuel if all of its loads are disconnected. (And I’m sure the ice will be shut off after running for a short time in a “spinning unloaded” mode).
Thus the amount of power supplied by the ice/gen to maintain the Volt’s battery at its minimum charge OR to propel the car is most easily & accurately controlled by the Volt’s control electronics, NOT primarily by the engine’s rpm or fuel mix.
Aug 26th, 2008 (12:15 am)customer depletion point:
– def -: The intersection where the number of customers drops off in relation to the purchase price.
- alt def -: What will happen if the Japanese EV offerings beat the Volt to the salesroom floor.
Aug 26th, 2008 (12:22 am)Many of these are basic questions/answers that are hard to understand if you dont have a technical background in motors, generators and batteries.
First point, none of the power the generator makes will be wasted, there is no way of “wasting power” sort of dumping the energy by heating up resistors. GM has stated many times that the gas engine will have enough power to drive the car at up to 110mph once the battery is depleted, there is also enough power to drive the car up a hill, loaded, at a certain speed.. that speed is unknown but it will not be below 70mph otherwise the car will get bad reviews.. What happens if the engine does not have enough power?.. the car will just simply run slower.. perhaps GM will allow you to use the remaining 35% power in the battery (at the expense of damaging the battery) but once that is used up the car will again slow down to the speed the engine allows.. it is automatic, and conventional cars do this also.. you may have the throttle floored but you are only going 55mph. Any Volkswagen Vannagon owner can tell you how it was going up a hill.
There are two possibilites: either the engine runs at variable rpm or it runs at 2-3 set speeds and just shuts off when not needed.. Up to GM how to do it, either way would work well with no “waste”. There is a “deadband” around 35% at wich the engine will maintain the battery, lets guess the engine will turn on when the battery reaches 34% and shut off when it reaches 36%, the battery is always connected to the motor and if the motor needs a big wallop of power it will get it from the batteries.. the generator attached to the engine is computer controlled to deliver the exact power needed.. the engine could be running unloaded at 3000rpm and suddenly the generator loads it and extracts 30kw of power, the engine compensates and keeps running at 3000rpm.. or they could vary the generator load and engine rpm at the same time to get the exact power needed.
Charge sustaining is just what it means, a way to protect the battery and to prevent it from beign discharged completely.. that is what the engine is doing, keeping the battery at the minimum charge point. Lets say you run out of gas and you have to go below the 35% point of the battery to get to your destination.. and you barely make it to your destination but there is no gas or electricity there to recharge the battery.. In about 3-7 days without recharging the battery will be irreparably damaged, completely gone, and will have to be replaced.. will GM cover this under the warranty?.. who knows?
They have stated that they will allow the driver to use up that last 35% of power if needed in an emergency.. but I bet it will void the warranty!.. on the other hand if they may still honor the warranty but the extra cost will be borne by all the other Volt owners.. in other words the battery will be extra expensive to cover the stupidity of a minority of the owners.. just pure speculation on my part.
So in conclusion, there will never be any power “wasted”, and it is not important if GM chooses a variable engine RPM or not.. whatever works best.
A quick note.. lithium batteries are stored and shipped at 50% charge, they self discharge very slowly (5% a year?, higher in hotter temps) but if they get too low they will die. What will be the protocol to store a Volt for several years?
Aug 26th, 2008 (12:31 am)The toyota prius stores hot water in a thermos bottle to preheat the engine prior to starting.. this is done to reduce startup pollution.. the engine shuts off at every stop light.
In the Volt, I would guess they could preheat the catalityc converter electrically.. after all it does have a huge battery.. about 13 times bigger than what the Prius has.
Aug 26th, 2008 (1:22 am)According to Wikipedia.com
EV1 The electric car lease to some GM customers
…
The Gen 1 cars got 55 to 75 miles (90 to 120 km) per charge with the Delco-manufactured lead-acid batteries, 75 to 100 miles (120-to-160 km) with the Gen 2 Panasonic lead-acid batteries, and 75 to 150 miles (120 to 240 km) per charge with Gen 2 Ovonic nickel-metal hydride batteries.
…
And you can get 75 – 150miles per charge and that’s 1999. I don’t understand after 9 years even if you do not invest any R&D, you (GM) try to tell us you get about 30miles per charge now? That’s bullock!!! GM, your reputation is already bankrupt and so do your business. I wish all GM shareholders good luck!
Aug 26th, 2008 (3:51 am)Farah – “But when the engine comes on to spin the generator, it does so with the idea that we’re generating electric energy to drive the wheels, not to charge the battery”
So the Motortrend chart showing the ICE cycling on and off is total BS. “Drive the wheels” means the engine stays on at 30% SOC.
The moment when the Volt hits 30% SOC, the ICE is going to come on and STAY ON until the Volt is plugged in again (no engine cycling while driving, but what happens at red lights is unknown). Wonderful, there goes my quiet car (on long trips). At least I won’t have to put up with the ICE starting and stopping over and over again. It will stay on, only the generator output will vary according the battery needs. At least it will save on starter motor wear and tear on the ICE.
The GM engineers need to clarify EXACTLY how long trips for the Volt will work. Until then, I am prepared to assume a worst case scenerio (poor GM engineering and planning).
Aug 26th, 2008 (5:51 am)#188 Ter — on defintions of “customer depletion point”
I love them. Thanks.
GM is making the Volt into a little bit of a joke here by tying it so closely to iPods and this strange lingo. What’s next? Maybe sold only to people with body piercings and green hair? Definitly will change the GM image, I suppose.
Aug 26th, 2008 (7:15 am)Grump@192
If I read it correctly in the chat, Bob Bonaface said that the Volt will shut down when stopped, including stop-and-go traffic.
Be well,
Tag
Aug 26th, 2008 (7:18 am)RB@193
“GM is making the Volt into a little bit of a joke here by tying it so closely to iPods and this strange lingo. What’s next? Maybe sold only to people with body piercings and green hair? Definitly will change the GM image, I suppose”
I know I’d sleep on the sidewalk the week before the Volt is released to get mine “activated”. Just like the Pod People.
Be well,
Tag
Aug 26th, 2008 (8:04 am)The Volt will not be judged just by Californians. The Volt will not be judged just by engineers. The Volt will not be judged just by economists. The Volt will not be judged just by celebrities. The Volt will not be judged at all by professional race drivers. The Volt will not be judged fairly by over-the-road truckers or RVers.
The Volt will be judged by Prius owners and hybrid Civic owners. The Volt will be judged by house husbands and business women. The Volt will be judged by ordinary people that need to go to work five days a week and then to visit their parents on the weekend. The Volt will be judged by folks in San Francisco, Chattanooga, Colorado Springs and Pittsburgh. The Volt will be judged by The Brady Bunch and The Simpsons. These are all part of the 70% of the population that the Volt MUST serve. These are all part of the “masses”.
The Volt cannot be an “econo-box”. It cannot be merely a “green” car. The Volt cannot be just a “commuter special”. The Volt will never be a diesel powered VW microbus. The Volt cannot be excused from any of the common use cases that other four door passenger cars serve. It will utterly fail if it cannot do what other four door passenger cars already do. The Volt will be a four door Chevrolet. Almost everyone knows what a four door Chevy is. They know what to expect. The Volt MUST live up to those expectations!!!
Aug 26th, 2008 (8:06 am)>>And you can get 75 – 150miles per charge and that’s 1999. I don’t understand after 9 years even if you do not invest any R&D, you (GM) try to tell us you get about 30miles per charge now? That’s bullock!!! GM, your reputation is already bankrupt and so do your business. I wish all GM shareholders good luck! >>>
It is 40 miles range btw, GM could get 100 miles, 200 miles if they wanted.. but no one would buy the car, too expensive and too heavy.
The beauty of the volt is a minimum sized battery so that 80% of the US would not have to buy gas.. I think 40 miles is too much, a 10 mile range would be enough and make the car a lot cheaper.
Toyota has been reducing the size of the Prius battery since it came out, to lower the cost of the car.
Aug 26th, 2008 (8:21 am)If I were GM, I’d stick to the 40 mile story. When they do better (and they will), the customer will be delighted because his/her expectations will be exceeded.
Remember … GM is trying to get 40 miles AER (All Electric Range) at EOL (End Of Life), and get 40 miles with air conditioning and other electrical consumers running. I’ll bet that in reasonably normal driving conditions some people will be able to get 50-60 miles or more at beginning of life.
I guess we’ll see.
And hey, this is just the first generation. (Compare the Prius technology in 1998 with the Prius technology now!) Batteries will get better over the next 10 years … lighter, smaller, higher energy density, longer lasting, safer, faster charging. Count on it.
Aug 26th, 2008 (8:26 am)#191 LivingWithLimits Says:
about EV-1:
“And you can get 75 – 150miles per charge and that’s 1999. I don’t understand after 9 years even if you do not invest any R&D, you (GM) try to tell us you get about 30miles per charge now? That’s bullock!!! GM, your reputation is already bankrupt and so do your business. I wish all GM shareholders good luck!”
———————————————————————–
The EV-1 was much more expensive, and was an electric only vehicle. The 150 miles was it’s max range. The battery used was much larger and was the only source of power.
The VOLT, is not supposed to be anywhere similiar to the EV-1. The VOLT runs for 40 (EOL (end of life)), not 30 as you have stated. Plus it gets around 400 miles at 50 mpg after that.
Anyway, these are simple facts to keep in mind. If you don’t like them, and the VOLT is not for you, than simply don’t buy one.
~Bob
Aug 26th, 2008 (8:38 am)hermant #196: “The Volt will be judged by folks in San Francisco, Chattanooga, Colorado Springs and Pittsburgh.”
Hmm, all of which are adjacent to big hills. Is that part of the point you’re making?
Aug 26th, 2008 (8:40 am)Some other facts that compare EV-1 to the VOLT:
EV-1:
300 L (vol) battery
80mph top speed
Seated two
Range 150miles
lead-acid and nickel metal hydride batteries (which weigh a lot)
VOLT:
100 L (vol) battery (1/3rd)
120mph top speed
Will seat 4
Range about 400 miles (40 miles pure electric)
lithium-ion batteries (lighter)
Some info for thought
!
Aug 26th, 2008 (9:43 am)this doesnt make sense. If you lower the engine rpm, not only the generator power drops but so does the generator output voltage.and frequency. Low voltage to the motors, batteries ect is a bad thing (generator will not contribute until voltsge exceeds batteries!
Aug 26th, 2008 (10:19 am)#185 Tagamet
“If I read it correctly in the chat, Bob Bonaface said that the Volt will shut down when stopped, including stop-and-go traffic.”
That would be great! And, that’s just how one would expect an electric car to behave.
Thanks Tag.
Aug 26th, 2008 (10:33 am)#190 Herm Perez
“The toyota prius stores hot water in a thermos bottle to preheat the engine prior to starting.. this is done to reduce startup pollution.. the engine shuts off at every stop light.
In the Volt, I would guess they could preheat the catalityc converter electrically.”
I hope you’re right. Moving that liquid mechanically is a fail point. Mine went out after a few years, and the only way I knew it was the sound at shut-off was different.
The dealer couldn’t detect it at first, until I recorded it and played it back to them. After they actually checked the part out, they said that, indeed, it had stopped working, and was then replaced under warranty.
Aug 26th, 2008 (11:03 am)#57 Dr. Science:
Very good, LOL. There’s always a litle diamond in the coal pile, if you search long enough.
#93 Murray:
Ditto #57. My head hurts too.
#167 Tagamet:
Well it took me awhile to work my way down to #167, but I knew it had to be here somewhere. That is the bottom line of this and every other thread. To which I might add – Tick Tock, tick tock, tick tock.
#171 Statik:
Right.
Aug 26th, 2008 (11:29 am)#194 Tagamet – I believe you’re right – and that’s the problem. Think about this – When does a gas engine get the worst miles per gallon? Answer – stop and go city driving.
Accelerating from a red light is the one task an ICE is worst at – and a battery is best at. That’s why the ICE should not be shut off at red lights – it can charge the battery, so the battery can be used to accelerate the car from a standing stop. Using just the ICE’s output to accelerate from a stop may sadly limit the Volt’s acceleration.
I can see why GM doesn’t want to overstress their Volt batteries – they’re under warranty. Lyle, we need a more detailed interview with Mr Farah, so these issues can be hammered out, once and for all. Everyone knows my opinion – (use the ICE to recharge the batteries, and get 40 more silent, gas free miles, over and over). That was my hope for the Volt. The truth may be much worse.
Let’s hear what Mr Farah has to say. He may be able to answer our concerns, if asked the right questions. Maybe you should buy him a few drinks first !
Aug 26th, 2008 (12:35 pm)>>this doesnt make sense. If you lower the engine rpm, not only the generator power drops but so does the generator output voltage.and frequency. Low voltage to the motors, batteries ect is a bad thing (generator will not contribute until voltsge exceeds batteries!<<<
this is only true in some cases.. there are generators that can produce high power even at low rpm, and the frequency does not matter, the volt uses a DC system. Power transformers are too heavy to be used in cars, thus DC-DC converters will be used as needed.
Aug 26th, 2008 (12:46 pm)>>I can see why GM doesn’t want to overstress their Volt batteries – they’re under warranty. Lyle, we need a more detailed interview with Mr Farah, so these issues can be hammered out, once and for all. Everyone knows my opinion – (use the ICE to recharge the batteries, and get 40 more silent, gas free miles, over and over). That was my hope for the Volt. The truth may be much worse. <<
Wheter you charge your battery from the wall socket or from the generator it still counts as a cycle.. A123 claims 7000 cycles is the life (they dont say shallow cycles or full 100% dischage cycles), but 7000 cycles times 40 miles per cycle is 280,000 miles, well above the 150,000 mile GM guarantee. It appears GM is acting very conservative with their battery. As many people say, it could be that the Volt will get a lot more than 40 miles per cycle.
In any case, why do you want to recharge the battery by using gasoline at $4 per gallon?.. makes no economic sense, just charge it at home. The Volt will be perfectly able to cross the USA with a discharged battery.
Aug 26th, 2008 (1:24 pm)208 Herm Perez –
1) what if you’re not going home? I doubt the Marriott would allow me to run an extension cord from my room to my Volt in the parking lot.
2) if the ICE is going to power the wheels after 30% SOC, I’m going to be using “$4.00 a gallon gas” anyway.
3) We would all love to see how you plan to cross the US on a depleted Volt battery without using “$4.00 a gallon gas”, as you say.
This is exactly why I asked Lyle to get Mr Farah to clarify things for us.
Aug 26th, 2008 (2:16 pm)I am curious if Volt will have a manual switch from electric to gasoline drive. I would be useful for burning out old gasoline in tank. Since gas engine does not charge the battery “emptying” the tank by burning the gasoline will be very difficult if not impossible and users will have to waist some old gas. If, on the other hand there is a switch, they would switch to gas drive with full battery and emply the tank – no waist there.
Aug 26th, 2008 (11:37 pm)>208 Herm Perez –
1) what if you’re not going home? I doubt the Marriott would allow me to run an extension cord from my room to my Volt in the parking lot. >>>
You get up in the morning and go to your Volt, the battery is still at 35% just like you left it last night.. you get in, the engine starts and you drive around.. a few days later you get home, the battery is still at 35% and you finally plug it in to recharge. Nothing is harmed.
>>2) if the ICE is going to power the wheels after 30% SOC, I’m going to be using “$4.00 a gallon gas” anyway.>>
that is the beauty of the volt.. you are not stranded when the battery is discharged.. true the engine will run, but just hard enough to drive the car, if you also want it to recharge the battery (wich it could) it will have to run harder and use more gasoline..
>>3) We would all love to see how you plan to cross the US on a depleted Volt battery without using “$4.00 a gallon gas”, as you say.>>
You misunderstand, you WILL HAVE TO USE GAS once the battery is depleted, but that does not mean you have to use twice as much gas to recharge the battery and also move the car. You could but it would be wasteful.. cheaper to recharge it at home.
Also, how much time do you think it takes to recharge the battery fully?.. hours and hours, you would have to drive for 6-8 hours to get it recharged fully.. that would use a lot of gas.
Nothing is free, if you hook up two 100w bulbs to a generator it will use twice as much gas as if you only loaded it with one 100w bulb.
Aug 26th, 2008 (11:44 pm)I think the biggest problem the Volt will have is stale gas.. I can see people not filling up the tank for two or three years… and God forbid you buy cheap gas.. it will turn to a mess in the tank after a year or so.
Aug 27th, 2008 (7:36 am)I guess my big question is what does the MPG work out to be when the battery is depleated?
I’m looking at replacing the family SUV with a Volt when they come out, but that means using it for road trips.
I thought that the generator would fully re-charge the battery, and that the mpg would be worked out as in (how many mpg it took to recharge/how far you could get while the battery is charging) +40 for the fully charged battery
or something to that effect.
so i guess the question is what will the Volt do on a road trip, and if i missed that post forgive me for restating the question.
*********************EDIT
NM I just saw the 50mpg article below this one
Aug 27th, 2008 (9:50 am)OK I have been reading all these posts, and one thing that comes to mind is that everyone wants an exact answer and you simply aren’t going to get it for several reasons I have listed below. I hope no one takes this personal but this poor engineer was actually trying to keep it simply, and it looks like everyone just won’t let him. Anyway the reasons it isn’t a simply reason.
1. Generators tend to have certain frequencies they run at that is something anyone who wants to look at Generac’s website who also uses Automotive engines in it’s larger units can clearly see the sweet spots where they will run something like 1800 RPM or 3600. Anyway you get the point.
2. The point about starting the engine to let it warm up is again something the many companies who build back power Genset’s have already figured out and taken into consideration as I know GM has as well. I hope everyone who thinks we need to warm up our cars has been educated by the many past TV Spots telling us this is no longer necessary. The reason being it wastes gasoline as the practice was tied to the drawbacks of the technology before fuel injection and computerized Engine Control & Managements systems or ECM’s which GM has been the leader in for decades.
3. The modern fuel injection systems can vary mixtures on the fly by modulating the width of the pulse coming from the electronically controlled fuel injectors which are controlled by the above mentioned ECM which measures by it’s sensory inputs many different variables such as altitude, ambient temperature, barometric pressure, air density ( via the MAP or manifold air pressure or MASS one is sometimes a back up for the other as the MASS uses a static electric grid to charge the input air to measure density) Anyone who has driven a older technology vehicle from sea level to 8,00 feet such as I did when I drove my 1985 Honda Accord from the caost Seattle adn then into CAsper Wy. will tell you they really lose alot of power as compared to a Electronic Fuel Injected vehicles such as my 1987 Pontica Fiero V-6 which I used on the next trip from fear I would be able to get the Honda back hoem again without taking another set of carborators calibrated for the higher altitude.
4. The above item wasn’t meant as a plug for GM, and a slam on Honda even if it actually was. I was just trying to make the point that GM has an extensive background in building very complex, and capable engine management systems that should make it very easy for them to adjust the runtime of the ICE if they determine that in certain regions the ICE needs to put out more power between cycles of charging the battery back to the “Customer Depletion Point” I suspect that in fact the technology the initially used on the Saturn’s where the Transmission had it’s own ECM that could talk to the MAIN ECM and request a modification in the shift points when it was determined they weren’t at the optimal point for the current terrain. I foresee the same kind of on the fly modification for the ICE run time if one was say in the situation mentioned above where the vehicles was doing more hill climbing than normal.
In closing I hope everyone takes these comments as not an attack at the constant Armchairs Quarterbacking or in our case Armchair R&D but a statement that we have a very capable team at GM who has for all intensive purposes all the resources of a company that according to many mechanics magazines has one of the most most capable Electronic Engine Management adn Engine design teams in the world. I know this is something that many either miss or aren’t aware of about GM, but I can tell you the boys in the land of strudel were very impressed in the abilities of the latest generation of engines from GM like the 500HP 20+ MPG Supercar engine in the Corvette LS& I haven’t even seen what they have to say yet about the newest Corvette which gets 625+ HP from a mere 6.2 liters and again avoid the gas guzzler tax that almost all imported supercars are forced to pay due to their really bad MPG numbers. Just compare a high end car from Germany or Italy and you will find two things constant across the board. Number one one of them get the MPG the Corvette does, and number two none of them cost less than $100,000.
I don’t love everything M does, and I beleive we still need to keep carefully watching the developments, and I am glad Lyle has the time to keep this website as current as it is, but come guys when you are given a high level answer like Lyle got this GM engineer to give please understand they really don’t have the time to explain the complex multi variable algorithms of the Engine Management Systems because if you thought “Customer Depletion ” was techno bable just image if they started explaining the exact nature of the way they engine computer would operate, and was to subject you to a much more complex discussion that I have above about the nature of optimal combustion fuel mixture and transmissions shift point for variable inputs or environments. I trust GM has taken into consideration all the things that have been discussed about such as hill climbing since many of their existing products backed upon ICE technology has already solved this problems. I would actually be more concerned about the products of many of the startup companies that have little or no experience in the field of ICE’s.
Elmer
Aug 27th, 2008 (11:31 am)Sounds interesting, but I heard it’s better for batteries to charge them up, then almost totally deplete them before charging them up again. So if you got lazy, kept refilling the tank, and just always kept your vehicle at a 30% charge, it might not be so great for the batteries? The system Aptera is using sounds like the batteries deplete at a slower rate (better for a battery) and that the depletion is constant until they lose their charge. I don’t know which system is better, but Aptera’s ability to get 300 mpg for 350 to 400 miles is pretty darn impressive.
Aug 27th, 2008 (2:40 pm)Somewhat of a contradiction regarding CDP. Quoting from Maximum Bob on the FlastLane blog:
“Another neat feature we will have because the vehicle is OnStar-equipped, is it will have logic in its brain that knows how far away from home it is because it’s used to being charged at a certain place. If you have taken a circuitous route home and are running low on battery, the computer knows “wait a minute, the guy is only 10 miles from home, no point giving him a full charge. I’ll just run the piston engine enough to give him a ten-mile charge because he’s going want to plug in at home”.
Aug 27th, 2008 (3:30 pm)If possible, please allow for power-user (off the standard menu) selections. Example: “Once I dip below 30%, aggressively [or mildly] charge my battery back up to full.”
Also good; allow for an out-of-gas and out-of-battery mode, where a user could deplete past the “I’m empty” 30% mark (perhaps to 10 or 15%) in sort of a limp-in mode to get to a gas station or plug-in.
Aug 27th, 2008 (7:20 pm)>>Sounds interesting, but I heard it’s better for batteries to charge them up, then almost totally deplete them before charging them up again. So if you got lazy, kept refilling the tank, and just always kept your vehicle at a 30% charge, it might not be so great for the batteries? >>>
This is not so, it actually hurts the battery when you get close to 0%.. it will kill the battery if kept at 0% for a couple of days. Toyota is even more careful with the Prius battery than GM is with the Volt’s.. Edison’s old Nickel-Iron batteries are the only ones (that I know of) that will take any abuse, some are still working after 100 years.
Aug 28th, 2008 (3:35 am)john1701A, I second your notion that basic information or a FAQ would be most helpful, considering some of the questions and comments that pop up:
“Okay, this may be a dumb question, but if the depletion point is 30%, then is the all electric range somewhere around 28 miles” A wise man once said “There are no dumb questions, just dumb answers”. From the beginning, the Volt plan was to get about 40 miles of driving from 8 Kwh, or half of the 16 Kwh battery pack. So it still gets 40 EV miles before reaching the depletion point at 30%. Tests have discovered that for this type of LiIon battery, getting the State of Charge above 85% or below 20% puts stress on the battery and shortens its life. Thats why GM chose the 80% to 30% SOC scheme, it maximizes battery life and reliability.
“will only a certain segment of the battery pack be charged (to 80%, for example) by the generator to run the wheels, leaving the other plug-in segment of the battery pack at 30% to preserve the life?” No, the entire battery charges and discharges at the same rate and to the same amount. There are even special circuits to keep all the individual cells that make up the battery at the same charge level, making sure no cell in the pack gets fully charged or excessively discharged. Designing it so different parts were at different charge levels would introduce a lot of major headaches for no good reason, and probably cause premature failue of certain parts of the battery pack.
“Take this scenario. There are three segments of the battery pack. 1. Plug-in only 2. Generator only, 3. Regenerative braking only, only releasing energy once 80% charge is reached. This would reduce the number of charge cycles each battery cell would see. Does anyone see a problem with this scenario?” Major problem. It is unnecessarily complicated, and one of those segments would inevitably get used much more than the others and fail much sooner. Someone who had a short daily commute would wear out the “plug-in only segment” long before the rarely used “generator only segment”. Besides, a single pack can handle all three functions without any problems.
“Does, for example, every minute charge through regenerative braking or a larger charge resulting from the ICE running have the same effect upon the battery as one that would take the 30% SOC to 80% SOC?” No, two half discharge/charge cycles aren’t the same as two full discharge/charge cycles, in fact, counts for sligtly less than one! Minor charge fluctuations hardly matter at all.
“Is the generator always directly linked to the wheels or does it only supply power once the CDP is reached?” The generator is directly linked to the IC engine, and produces electrical power when the ICE is running. Electricity powers the motor that drives the wheels, and that electricity can come from the generator and/or the battery. During regenerative braking or when the generator is producing more power than the motor needs, the surplus electricity can go to recharge the battery.
“Will the Volt dump the generators excess power or will it adjust the generator output to match the cars needs?” Most of the generator output goes directly to the motor powering the wheels, and any excess goes to charge the battery. Once the SOC reaches a sufficiently high level, about 40%, the generator can shut off and the car resumes EV mode driving. But the power output of the IC engine and generator can be increased if necessary, like on the proverbial “going up a steep mountain pass while towing a trailer”, although the fuel economy would drop a bit.
“I am curious if the generator is A.C. or D.C.” Most likely AC, as varying output frequency really isn’t a problem here, it can easily be rectified to DC, and AC generators are usually brushless and need less maintenance.
“I think the biggest problem the Volt will have is stale gas..” That problem has already been solved, by the use of a sealed bladder style tank. The problem with gas going bad with age is caused by evaporation of ligher components, oxidation, and contamination, and a bladder tank keeps out air and prevents all of those causes.
“Sounds interesting, but I heard it’s better for batteries to charge them up, then almost totally deplete them before charging them up again.” That is only true for NiCad batteries, due to a NiCad phenomenon called “memory”. It is NOT TRUE for lead acid, NiMH, or any kind of LiIon battery, and for all of those battery types, deep depletion will shorten their lifespan, and they don’t suffer from the memory effect.
Jan 10th, 2009 (6:39 am)Here are some ideas for the next VOLT version which is adding some solar cell soft membrane on the top, the trunk and the hood.
The ICE generator would be smaller and less polluant using a Bio-Diesel type and finally the Lithium-Ion batteries would be replaced with Dr. Cui newest technology called the Silicon Nanowire Battery which holds 10 times the charge of existing Li-ion battery and will be a lot cheaper.
Aug 18th, 2009 (7:15 pm)I have been trying to understand some conflicting statements (at least to me)’
I was under the impression that the engine-generator combination runs at a selected constant speed, correspoinding to the maximum efficiency of the engine. Someone stated that the power is used ONLY to drive the motor, gear and wheels, not to charge the battery Recharging only occurs by regeneration during braking (deceleration)
From a usual torque-hp-efficiency vs rpm characteristic of a gasoline engine, the maximum efficiency occurs somewhere around 75 percent of the rpm for maximum hp…. In a straight gasoline./AT car,( to slow down if you take your foot off the gas pedal, the engine slows to idle, if the car speed is still too high you need to brake)
if the hp demand decreases below this point the engine slows down to the point where the engine torque x rpm match the demand.. For the Volt this demand is the power required to drive the wheels reflected back into the drive motor/gearbox and generator..
From a spec I copied, the Volt engine is a 3cyl.1.0 litre, turbo charged 160hp/120kw gasoline engine, with “nominal” speed of 1500-1800 rpm, maximum 3200 rpm,,Presumably this nominal speed is the speed for maximum efficiency.at which the engine runs continuously.
Aug 18th, 2009 (7:34 pm)What happened to the road resistance and air resistance at 70 mph?
Aug 18th, 2009 (7:54 pm)From the article cited, GM claims the energy consumption for 40 miles in the ‘electric mode’ assume city driving is half the battery capacity, or 8 kwH
I drive an old Honda Civic, 1.5 llire gasoline engine with AT, estimate around 24 mpg city driving using regular gasoline (no alchohol) Checking some data which I;ve long forgotten that works out to around 36 +kwH /24 miles or roughtly 1.5 kwH/mile or 60 kwH for 40 miles
GM specs give the mechanical transmission efficiency at around 0.89 , (45 kW electrical in/40 kW mechanical out) which would correspond to a vehicle energy consumption of 7.1 kwH
Is it possible the efficiency of my vehicle is only 7.1/60 or 12 percent?
I imagine that the control system somehow maintains a constant rpm of the engine/generator combination by reducing the fuel input when the demand drops. How does that affect engine efficiency ?(the statement is that the engine runs at constant speed and maximum efficiency)
Aug 18th, 2009 (8:09 pm)I’ve been searching for that information also, as well as some spec on the electric motor and drive train. (Asynchronous, 120 kw, 3 phase, frequency controlled? with a reduction gear?)
I live in Florida where the temperatures have been over 90F these past few weeks, so I use the A/C every time I step in the car and if I leave it 45 minutes in a parking lot the steering wheel gets too hot to hold. A similar situation, in reverse, would apply to those pore guys who live up north , in those cold dark winter days Half an hour to defrost the windshield..Brrrh!
No one in these discussions seems to use air conditioning in the summer or heat in the winter.Have you any idea how much energy those require, presumably from the same battery pack?
Aug 18th, 2009 (8:48 pm)“..since a HPhr of energy generated by the ICE costs about 3 times as much as a HPhr of energy drawn from the battery, you want to run the ICE as little as possible..”
I am addressing only this part of your comment. How did you arrive at this conclusion?
Here in Jacksonville Fl regular gasoline with about 10 percent alcohol retails for $2.60 I estimate the energy content about 35 kwh per gallon of the mixture (I may not be accurate, if so, please correct
0.9 gal regular gasoline = 0.9 x 125,000 =112,500 BTU
0.1 gal ethanol = 0.1 x 84,000 = 8,400 BTU
Total energy content of mixture =120,900 BTU =35.4 kwH
GM says it uses a 1 litre turbo charged gasoline engine, I don’t know its efficiency, let’s assume 0.30 also a generator eff of 0.92
Combined eff = 0.28
output = 9.8 kwH per gallon of mixture @ $2.60
Cost per kwH from the ICE = 26.6 cents
I paid 12.83 cents per kwH on my last bill, the ratio is about 2:1
As an aside, an article in our local paper quoted MrHenderson ceo of GM as stating that “the cost of charging the Volt is about 40 cents a day at 5 cents per kwH” That’s for 8 kwH driving 40 miles.
1 cent a mile!!!!
I assume Mr Henderson has solar panels on his roof or GM pays his electric bill.
Aug 18th, 2009 (9:15 pm)“.. “If you have a propulsion system in which a small efficient gasoline engine powers an onboard generator which in turn supplies electrical energy to an electric motor to propel the car at 50 mpg, why would you not employ this system as a mainline powerplant without the expensive batteries?..”
That same thought occurred to me’
I would assume the 50 mpg is obtained by recovering regeneration energy during deceleration which would otherwise be dissipated as heat when braking a car with straight ICE drive and transmission
They have to store this regeneration energy somewhere, hence the battery
the minus side of course is the expensive battery which weighs 400 lbs and occupies space, and battery maintenance which is still an unknown factor.
How many persons could afford/would purchase a car transporting 4 persons for 40 thousand dollars?