One-on-One with Jon Lauckner, VP of Global Program Management, Part 3
With respect to the Volt’s combustion engine, if it keeps at the same RPM will it be more efficient than an engine whose RPM varies?
You see this efficiency argument play out in CVT transmissions. You jump in a car with a CVT and what you do is you push the gas pedal down and the engine automatically speeds up to fairly high levels and you have many thousands of RPMs, maybe 2000 or 3000 RPM and meanwhile the vehicle speed is very low. Then over time, it’s this motorboat feel you know “Wheeeee” and this slowly, slowly speeding up of the vehicle. What’s going on there? Well the theory of a CVT is you put the engine at its most efficient operating point and you let the gear multiplication of a CVT take care of the change in wheel speed and tractive effort. This is the whole idea.
Well the same thing can be true in an internal combustion engine when you run it at a relatively constant speed and load, you can optimize the engine around those conditions. And so when we get cars on the road (Volt mules) and we really start the development program, that’s when were really going to start to explore, can we run this thing when we’re charging at relatively constant speed and load within 2 or 3 points and really ‘milk’ the efficiency of an internal combustion engine a little bit better than when its operating over a huge range of speed and load, from 0 RPM to 5000 RPM.
Have you decided on actually which combustion engine the Volt will use?
It will definitely be a gasoline engine running E85. We cant give up everything at the very first moment or we’ll spoil the suspense.
Lets talk about batteries. The popular chemistry for lithium ion batteries out there for laptops and cellphones and PDAs is using cobalt oxide. The manganese spinel variant is the variation that LG Chem is chasing after. Lithium iron phosphate is the family of chemistry that A123 systems is working on. People talk about lithium-ion battereis overheating, but interestingly enough, it’s the tendency for lithium cobalt oxide to overheat when it’s discharged in a very robust way, a very strong way, (that people worry about), (on the contrary) the spinel-based chemistry is much more tolerant and has a relatively low amount of temperature rise when its heavily discharged. The other thing I’d offer is that our friends at LG Chem, for ‘our’ batteries, because you have to know LG Chem makes a lot of batteries, a lot of types, but for ‘ours’ they are going to use a special separator, the safety reinforced separator or ‘SRS’, to provide additional protection against these kinds of things.
And then of course you’ve got the whole story of the thermal management system for the battery that is basically there to keep it cool, around 20 degrees C where batteries are happiest. Where they perform their very best.
What I think is interesting is that our friends at LG chem have told us is that they are trying to get their customers of the can batteries the 18650 batteries, the cells, they’re trying to get them to move over to the separator approach.
The point Id like to get across is that not all lithium-ion batteries are created equal. These laptop batteries, they were rejected out of hand at the very beginning. At the very beginning we said we will have nothing to do with this cobalt oxide stuff. Because we know that its a challenge right from the get go.
You’ve also hear about this breakthrough at Stanford University that broke last month where they said that they could use these Silicon nanowires.
I interviewed the inventor. Did you guys speak to him?
I think if you talk to our battery folks, they would say they are pretty optimistic about it. The idea of using silicon has somehow been in the game but nobody has been able to develop these nanowires so far that didn’t deteriorate over time, that didn’t have mechanical failures, because they swell and shrunk they would tend to deteriorate over time. Apparently Stanford found a solution, and if they had, it’s huge. It’s huge.
We do a lot of testing of cells, and the door to working with General Motors is always open. In fact, than rather submit a white paper with claims, we’d just as soon have you submit a cell. Well get to the bottom of it real fast. The reason that done is that USABC has developed a lot of standardized tests and we have a lot of standardized tests of our own, and depending on how you load a cell and how you cycle a cell and lots of other variations you get different results. So if you want to know where you are at, if we get a cell we can test it with a very rich understanding of how it ought to behave at a certain time, and it makes it very easy for us to get to the bottom of exactly what claims are being made and what’s actually going on.
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January 24th, 2008 at 6:41 am
Thanks Lyle more interesting information, especially on silicon nanowires (wait, what does LifePo… think of this)
Being frenchspeaking, I was not able to understand the quote below, could anyone help. Thanks.
“What I think is interesting is that our friends at LG chem have told us is that they are trying to get their customers of the can batteries the 18650 batteries, the cells, they’re trying to get them to move over to the separator approach.”
January 24th, 2008 at 7:16 am
#1, I think it means something like:
“Here is something interesting: Our friends at LG Chemical have been trying to convince their other customers (such as those buying ‘can’ batteries or ‘18650′ batteries) to use the separator system that GM is planning ot use.”
And since LG is trying to convince others to use the SRS in their batteries, the implication of course is that it is better than any existing lithium-ion battery technology.
January 24th, 2008 at 7:20 am
I think he meant “trying to get their customers OFF the can batteries” but I’m not sure. English is my native language and it confused me too.
January 24th, 2008 at 7:48 am
He means LG’s current cannister-shaped cells called 18650s.
January 24th, 2008 at 8:03 am
Like the guy said, any car with a CVT is designed to keep the engine in its most efficient rev range if possible.
You can think of the Volt’s battery and electric motor as the most awesome CVT ever. Power from the engine drives the wheels at any speed you want.
January 24th, 2008 at 8:05 am
Thanks to all for your interpretation of the quote.
January 24th, 2008 at 8:12 am
#5 Tom exactly, that’s why diesel locomotives use an electric drive, because otherwise the transmission has to be huge to carry the torque required at low RPM (see: http://en.wikipedia.org/wiki/British_Rail_10100)
As has been discussed in other threads though, I think the real advantage of the series hybrid drivetrain is the ease with which you can change fuel sources.
Depending on the amount of efficiency they squeeze out of system integration (using waste heat from engine to keep battery warm, etc.), the generator could be completely modular and thus easy to change. If they ever get PEM fuel cells working, well, just replace the gasoline generator with a fuel cell. If your country has cheap ethanol due to the effective subsidy created by slash-and-burn agriculture in the world’s largest rainforest, well, put in an ethanol burner
The list goes on.
January 24th, 2008 at 8:19 am
Re: my comment in #7. To clarify, I mostly mean that the fuel-agnosticism of the E-Flex drivetrain is an advantage for GM. By standardizing on the architecture but allowing different “generator modules” to be put in for different parts of the world, the company can save a lot of money in production costs. However, it’s not like individual drivers are going to be swapping out the generator modules at the drop of a hat!
January 24th, 2008 at 8:27 am
#7, Geoff:
I’m not sure why the Volt’s “range extender” would be any more or less easy to swap than the engine in a regular car. Cars are already designed in a fairly modular way that allows the manufacturer to sell one trim with, say, a 4 cylinder engine, and another trim with a completely different 6 cylinder engine. Or one with gas and another with diesel. Etc.
No matter how modular and easy they make it, it’s not going to be something the customer will change after a sale, just like you wouldn’t ask your mechanic to convert your car to a diesel. (Well, maybe some people do, but in general…) The Volt will no doubt have a radiator in the front and exhaust in the back and it would require a lift and an engine crane and about a million hours to swap everything.
January 24th, 2008 at 8:46 am
As always, Lyle, an excellent interview! The two primary things I gather from today’s segment are:
1) The emphasis on keeping the range-extending ICE at a nearly-constant rpm makes it unlikely GM will have a Volt operating mode that mechanically couples the ICE directly to the wheels. However, this doesn’t rule out the possibility of an **electrical** bypass mode (generator-to-motor, as in a locomotive) for unusual loads such as a drive up Pike’s Peak, as Lauckner’s comments yesterday seemed to imply they might be considering.
2) I’m VERY pleased to hear about their emphasis on robust ’safety reinforced separators’ or ‘SRS’ cathode/anode plate insulators. Any battery’s performance dictates that its plates be extremely closely spaced, and separator materials deteriorate over time. Since a single separator “punch-thru” can short an entire cell, plate separators are critically-important elements of long-life batteries, whether in space or automotive applications. (Note to GM Marketing: “The Volt’s batteries have ‘SRS’, the ‘air bags’ of batteries!”)
One more thing: I’m certain GM will design the underbody battery compartment to allow access for battery servicing and/or sub-pack replacement if necessary. Lauckner’s comments on the Stanford silicon nanowire research suggest to me that they’ll be placing even more emphasis on ease of access to replace the ENTIRE battery. Whatever future battery technologies may prevail, its certain they’ll all permit a reduction in overall battery size (as well as increased capacity), so they’ll be able to easily fit in the Volt’s battery compartment.
I’ve always seen **battery longevity** as the major unknowable parameter in any new EV design, which makes it a real marketing ‘bug-a-boo’. But if a Volt saleman is able to say that the Volt drive train, including the battery, is fully covered by GM’s 100,000mi warranty (and, hopefully, GM will extend their 5yr time limit to 10 yrs like Hyundai), and buyers know the battery is designed to be replaceable, that marketing pitfall can largely be avoided!
January 24th, 2008 at 8:56 am
I’m intrigued by the evasiveness regarding the engine. He didn’t confirm it is internal combustion only gasoline / e85 burning. Does that mean they’re looking at some of the experimental engines like the cyclone?
http://www.cyclonepower.com/video.html
I wonder what ’surprise’ could mean? If they’re going away from IC, this will be a truly revolutionary car!
January 24th, 2008 at 9:14 am
Chris @ 11, don’t get carried away. GM has said all along they were going with an E85 ICE for the range extender. I’ll bet we can start some dandy rumors around here.
Although I drive and love diesel, Biodiesel gelling issues (with the cold) may persuade me to encourage the E85 option rather than the diesel. Plus the cost would be too high. We know hydrogen is out.
January 24th, 2008 at 9:44 am
Dave B #12
I also drive cars with excellent diesel engines.
In winter the last problem I had with a diesel was in 1987. It was frozing at - 19° Celsius with a strong north wind and a snow storm.
After that (a lot of diesel engines have been out of order at that time) the European car makers have all put a diesel heater and in winter the gas stations distribute a guaranteed fluid diesel down to -20° Celsius.
So, since the beginning of the ’90’s, we have never know any more problems of gelling diesel.
January 24th, 2008 at 10:05 am
Dave (#12) Biodiesel cold temperature jelling is a problem in INTERNAL combustion engines because it clogs high pressure pumps and injectors needed to fully atomize the fuel for complete combustion.
This is a non-issue with EXTERNAL combustion because the Cyclone burns the fuel for heat instead of trying to atomize and explode it for expansion. In fact, external combustion can burn ANY combination of liquid hydrocarbons and will continue to burn the fuel in a centrifugal chamber until all hydrocarbons are converted into heat.
You could buy whatever is cheap including but not limited to diesel, biodiesel, kerosene, used motor oil, ethanol, butanol, gasoline, hydraulic fluid, etc. or some combination of all of the above. Just poor it in your tank and the Cyclone can burn it cleanly.
Talk about the ultimate Flex-Fuel engine!
January 24th, 2008 at 10:25 am
Tim @ 14, I’m skeptical. I don’t know enough about engines except if this thing can burn trash as their website boasts, why haven’t one of the majors bought the patent?
I’d encourage GM to fast track the Volt to market focusing on the 40 mile EV range rather than all the bells and whistles of technology which is going to delay this thing…look at the Tesla Roadster. They screwed around with 2 gear transmissions with 4 different manufacturers before they finally went simple and dropped it to one speed.
January 24th, 2008 at 10:30 am
Two comments: 1) Consumer Reports did a report on CVT’s by comparing the efficiency in MPG of a CVT vs an automatic transmission. The result: Don’t waste your money on a CVT the cost benefit ratio is not there and they found efficiencies almost the same between the two. No break through there & comparing your ICE to a CVT may not be such as good thing after that report. 2) Tim #4 External combustion process with brake fluid, used motor oil etc.. I doubt it burns clean, there must certainly be a hydrocarbon by product IE carbon monoxide along with other green house gases. Only thing your going to burn in that engine that is relatively clean is Natural gas!Lets not make that engine out to something it is not, if there was no emission byproduct everyone would be using it to skirt emission requirements now. Clean burning is one thing it is not.
January 24th, 2008 at 10:43 am
Didn’t GM say there would be a turbo (or maybe two turbos?) on the engine, to further take advantage of constant RPM and increase efficiency?
Also, I would like to know more about the electric motors that will be used in the Volt.
January 24th, 2008 at 10:56 am
The posability of the generator coming on to aid the battery during extreme loads might give the same battery a chance in a truck and even give it towing capability am I correct?
If they could pull off a full size pick-up with 4 wheel motors gm would own the auto industry!
January 24th, 2008 at 11:25 am
Dave B, #15:
As to the bells and whistles, I could not possibly agree with you more.
It’s not only the delay, it’s the price. Rumors of $40k just took the wind right out of my sails.
January 24th, 2008 at 11:34 am
Dave B #15 & Noel Park #19:
I generally agree with you both. But a feature like the glass/polycarbonate electrochromic roof can easily be offered as an added-cost option, and as such it would give the Volt the pizazz any new model needs to supercharge sales …even sales of the base model!!!
January 24th, 2008 at 11:38 am
PS: Even if the glass roof were offered as a smaller sun-roof-sized option, the fact it ‘opens/closes’ WITHOUT worsening the Volt’s aerodynamics would still get lots of media attention for the Volt.
January 24th, 2008 at 12:25 pm
Brian M #17:
Yes, GM has described the ICE as having a turbo & as running on either gas or E-85.
Regarding your question about the electric drive motor, it has been reported elsewhere that the Volt’s 160HP AC motor will be similar to (but obviously a scaled-up version of) the motor they’re using in the Chevy Fuel Cell Equinox, a single 97-horsepower AC motor with 236 pound-feet of torque driving the front wheels. Since GM claims this mid-sized, large-frontal-area SUV will reach 100mph, I would guess the 0.25 CD (or less) & lighter-weight Volt would reach 120+ in a breeze! (I also think GM is understating the Volt’s 0-60 time & that something like 6.5-7.5secs is more likely than the 8-8.5 they quote.)
January 24th, 2008 at 12:26 pm
Dave B Says:
January 24th, 2008 at 9:14 am
Chris @ 11, don’t get carried away. GM has said all along they were going with an E85 ICE for the range extender. I’ll bet we can start some dandy rumors around here.
Although I drive and love diesel, Biodiesel gelling issues (with the cold) may persuade me to encourage the E85 option rather than the diesel. Plus the cost would be too high. We know hydrogen is out.
Wise:
I’m guessing the smallest off the shelf ICE that they have in production. I don’t think they have time to develop an ICE from scratch. It may be from another division of GM world-wide.
January 24th, 2008 at 12:43 pm
maybe off topic:
Any international executives or engineers at GM as of this past Monday will not be allowed to obtain Michigan State Drivers licenses.
http://www.michigan.gov/documents/sos/Applying_for_lic_or_ID_SOS_428_222146_7.pdf
The I551 that this document refers to is a “green card”, however, often executives do not have green cards they have L1 visas. Engineers would typically have H1 or L2 visas.
So in Michigan’s attempts to crack down on illegal immigration they have managed to bar some legal Detroit car executives managers & engineers from driving their own vehicles.
And no an international drivers license won’t do, because you cannot always get insurance with that, and you cannot always renew a foreign license even if you could get insurance.
So much for Michigan attracting the best and the brightest from around the world.
January 24th, 2008 at 1:00 pm
Two quick points:
1)Well the theory of a CVT is you put the engine at its most efficient operating point and you let the gear multiplication of a CVT take care of the change in wheel speed and tractive effort. This is the whole idea.
Well the same thing can be true in an internal combustion engine when you run it at a relatively constant speed and load
It would seem that the Volt setup would be superior to the CVT because it puts the engine at constant speed AND load, not just constant speed.
2) With regards to the whole pricing issue, one option GM could do alongside leasing the battery pack is to get the tax credit to apply to the base cost of the vehicle (chassis, motor, engine etc). Suppose that costs 20,000. Given a fairly aggressive tax credit of $7k, the dealers could get the cars out to door for $13k!
January 24th, 2008 at 1:06 pm
nasaman, #20:
Add on option, no problem. Just keep the base price and the delivery schedule under control.
Plus it places more information, and thus power, in the hands of the consumer. If it costs $500, I might do it. If it costs $5000, probably not. If the $5000 becomes part of the base price, and pushes it over my can’t swallow it level ($40k? You’ve got to be kidding.), I’m out of the game. Not smart marketing, IMHO.
Back in the 60’s, when manufacturing was coordinated with paper, pencils, slide rules, Frieden calculators, and telephones, the Corvette, for one example, had an options list as long as your arm. A large proportion were special ordered to suit the individual customer.
In this day of computer controlled production and instant communication, I cannot see how this could possibly be “too hard”. I recently read a fascinating report on how Penske is planning to go to a highly sophisticated version of this for the Smart. They believe that this will have all sorts of good impacts on inventory, need for physical plant at the dealer level, leftover cars with unpopular options packages which have to be discounted to move, and various other issues.
Many have already made this point, but one more time never hurts. The base car will be enough of a technological leap to daunt anyone. Let’s get it into the hands of the public, and follow up with all of these cool extra cost options as engineering time and resources allow.
A wise man once famously said, “Do not let the perfect become the enemy of the good.” In this case it might be more like, “Don’t let the absolute ultimate become the enemy of the spectacular step forward.”
January 24th, 2008 at 2:16 pm
It probably won’t be, but I’m hoping the ICE is HCCI. Then on long trips you’d get diesel-like mileage.
January 24th, 2008 at 2:21 pm
Easier to swap because:
> Engine is much smaller than most comparable automobile motors, this due to it being optimized for a single efficiency.
> No transmission to disconnect. Just electrical wires to cell packs and bolts for securing. The entire motor unit could be designed to be self-contained. (Heck, pop-it off and use it as a home generator.)
> This also means the motor could easily be in the rear or elsewhere.
> Radiator, water pump, etc. May or may not need to be. Very much depends on the engine.
***
Regarding Diesel…
No reason for a diesel at this time in the U.S. The European version of the Volt (an Opal) is going to be a diesel generator.
Why no diesel yet?
Because U.S. diesel is dirty and has high quantities of sulfur. Diesel tends to fail most air quality standards. Currently, the U.S. is retrofitting it’s way toward cleaner reduced sulfur diesel. Was supposed to be done by now, but as always is taking longer. However, I expect in about 6-8 yrs you’ll see the diesel - or sooner if clean diesel arrives earlier.
***
One thing that would be sweet. If there are 4-motors (one for each wheel). Think of what you could do with suspension, turning, traction control, and more?
> Direct to wheel traction control
> Independent suspension with less loss of power
> Turning, could we make the wheels capable of a 180 degree rotation? I mean, think of what parallel parking would be like. Pull up the spot. Rotate wheels to a perpendicular angle and the vehicle just slides sideways into the parking spot.
***
Marketing….
I was thinking regarding the talk that they might not be able to keep early released version under $30,000. I was really hoping for a $20,000+ price - oh well.
But I think GM should offer this deal to purchasers:
“Guaranteed trade-in value! GM will guarantee the first owner a minimum of $5,000 trade-in on a new GM vehicle - regardless of mileage or age. 7 yrs of ownership must have elapsed before trade-in.”
Essentially, GM would be gambling on the success of the vehicle. When people go “Hey this costs about $5,000 more than your other vehicles.” GM can point to this offer. Essentially, with the hope that they will be rejuvenated and in a better financial position in 10 yrs thanks to the Volt. The idea being even if your Volt is 12 yrs old with 212,000 miles on it. If you go to trade it in on a new purchase of a Chevy vehicle - you’d be guaranteed a minimum of $5,000 in trade-in.
a) this reduces the loss of value in the long-term if vehicle is kept as a single owner
b) increases future likelihood of new purchase from GM.
c) offsets some of the additional costs to ensure enough volume of sales
Downside:
For GM: if GM doesn’t find it’s way to a better position within 10 yrs, it could hit the company’s profits pretty hard in the future.
For the Buyer: if the Volt were to be a total lemon, you’d have to hold onto it in order to receive the benefit. On the flip side, if you did and it was a total lemon, at least you can recoup $5 grand.
January 24th, 2008 at 2:37 pm
Forgive me for belaboring the point, but I just couldn’t care less about the glass roof.
Our last import, before we swore them off, was a 1987 Nissan Maxima. It had a very nice glass electric sunroof. We probably opened it 10 times, if that, in the 8 years we had the car. It had a sliding panel which blocked the glass to keep the sun out of the interior. It ended up remaining closed about 99.99% of the time.
Our present car which replaced it, a 1995 Impala SS, has no sunroof. We have not missed it for 1 second in going on 13 years.
I do not want to spend 1 cent extra on any kind of a glass roof.
How about some kind of an adjustable ride height feature to improve the Cd at highway speed, if we need gee whiz gizmos. I coud get into that! If not, no problem. KISS.
January 24th, 2008 at 2:47 pm
#28 noel park
I’m with you. We have a Corvette with the glass targa top and it just heats up the interior when you least want it. Thank God the G6 has a slide cover to stop the sun from beating in.
The top in the show car looks cool but I just don’t see it in every car but if it’s an option the dealers will order it to drive up the price.
January 24th, 2008 at 2:51 pm
#29 noel park Says: “Forgive me for belaboring the point, but I just couldn’t care less about the glass roof. ”
Noel, I couldn’t agree more. A normal roof will be fine with me if that brings the price down below $30K. I’m not buying a $40K unproven car. $30K is pushing it, but I will do it.
January 24th, 2008 at 3:00 pm
Another thing I noticed-
“gasoline engine running on E85″
Mr.Lauckner evidently means an engine designed to withstand the corrosive nature of ethanol, but not necessarily an engine optimized to take advantage of ethanol’s higher octane number.
There was some work done by Saab on variable compression ratio engines. The project got shelved by GM when they bought Saab. Maybe it’s time to restart that program?
January 24th, 2008 at 3:32 pm
Jason #28 -
Low sulphur diesel is already in place. That is not the holdup. The issue is the low NOx and particulate requirements are difficult to achive without some form of aftertreatmeent - either a DPF to clean particulates while optimizing combustion for low-NOx or by using a Urea-assisted catalyst tolower NOx and optimizing combustion for low particulates. Either the DPF or SCR solution is quite expensive and would make reaching the cost targets of the Volt more difficult to achieve. And by 2010 the requirements get even tighter and will probably mean that both DPF and SCR will be required.
January 24th, 2008 at 3:35 pm
thatsanicepicture, #30, Rashiid, #13:
Thanks guys. Sometimes (usually?) I think I’m talking to myself!
The dealers ordering expensive options to drive up the price gets back to my comment about custom ordering of cars. In the old days, you used to be able to special order a Corvette and get it in 6 weeks. You might think that it would be easier now, given the massively better tchnology. Even so, I would happily wait 6 weeks to get my Volt the way I want it.
We have friends who waited 6 months to get a Prius.
The only time I buy a vehicle from dealer inventory is when the rebates and deals get so good I can swallow getting options I don’t need, or not getting ones I want. This is no way for the manufacturers to make money. It will be interesting to see how Rodger does with making most Smarts special order.
My younger son recently bought a Mini Cooper which was special oredred from England(!) and arrived in about 8 weeks, so what’s the problem?
January 24th, 2008 at 4:31 pm
The Volt won’t run its engine at constant speed or load. There will be varying demands on the engine as the driver accelerates and slows down during normal driving. If you want to see how the Volt engine will run, just hop into any one of the many CVT vehicles available today and try it out. There is some effort to keep the RPMs constant when possible but the load obviously varies as you drive.
January 24th, 2008 at 4:43 pm
Why cant you charge the battery at constant current, and provide the varying driving loads from the battery?
January 24th, 2008 at 5:00 pm
#36, Jim D:
The battery normally charges (8 kWh) in 6 hours. For the sake of longevity, it’s not good to charge the battery too fast. Let’s say it’s probably fine to charge it in 1 hour. That means it takes a maximum of 8 kW to charge.
The ICE can put out 56 kW. So that means a maximum of 15% of its output can be used to charge the battery at full speed, giving it an operating range of 15% to 100%, which is really only 15% different from any regular car engine.
January 24th, 2008 at 5:06 pm
Tom-
I disagree. The Volt’s engine should stay at constant speed and load, and use the battery’s remaining energy (which is still 30%SOC or above) to compensate for power spikes. Surplus energy just flows into the battery.
To do otherwise would be a horrible mistake, and defeat the entire point of the exercise. Look at the multitude of series hybrids already in existence in the form of series hybrid buses, and you will quickly see that you are incorrect in your assumptions.
As an example:
From http://www.greencarcongress.com/2007/05/daimlerchrysler_1.html:
“The torque curve of the hybrid-bus engine is tailored to the frequent steady-state operation of a series hybrid application, resulting in optimal emissions performance and fuel efficiency.”
A possible caveat to this is the setup of this microturbine-powered series hybrid:
http://www.greencarcongress.com/2007/10/microturbine-se.html
“When the batteries are at a high charge level (>70%), the APU reduces the input to the batteries. At this level, the bus can operate in an electric mode with the APU turned off. At a medium state of charge (40% - 70%), the APU adjusts its output to maintain the average state of charge. Should the SOC drop below 40%, the APU will increase its output to return the battery level back to the required state of charge.”
However, this design still does NOT follow the inferior power-on-demand type operation cycle which you are describing. It is a much more macroscopic adjustment of output.
January 24th, 2008 at 5:16 pm
Tom-
I’m really not sure what you’re arguing in #37, nor do you really seem to be answering Jim’s question. The battery should be able to withstand the incoming energy from charge-sustaining mode (not to mention regenerative braking!) just fine, just as NiMH cells have done for years using only a small % of their capacity.
If the Volt is going to achieve 45+mpg, it needs to follow the steady-state regime, just as Mr.Lauckner has clearly indicated.
January 24th, 2008 at 5:17 pm
Tom #35 & Jim D #36:
To make a pretty close analogy, the huge solar arrays, by themselves on the ISS (Int’l Space Station), would “sag” badly under even MODEST loads. However, the ISS batteries do NOT sag noticeably under even very HEAVY loads …i.e., the solar array’s job is really just to charge the ISS batteries, which then power the space station.
The Volt E-REV design is similar. The Volt’s battery provides smooth electrical power to the controller/motor/wheels, and the ICE/Generator’s job is simply to charge the battery. Like the ISS solar array, the ICE/Generator is designed to provide an essentially CONSTANT output to charge the battery, which means that the ICE should run at a fairly constant rpm …even if a Volt driver ‘floorboards’ his accelerator!
January 24th, 2008 at 5:22 pm
AES, what constant load do you think the Volt engine should operate at?
If it’s 15%, it will charge the battery at a pretty quick rate (1 hour) if the car is stopped but as soon as you get going at highway speeds, the battery will become completely drained after a few minutes.
If it’s 100%, it will charge the battery in 10 minutes if you’re stopped, which is much too fast and will render it worthless after a few months.
I don’t know how they make buses work with “frequent steady-state operation” but I don’t see how it’s possible with the Volt.
January 24th, 2008 at 5:48 pm
AES and nasaman, the point that I’m trying to make is that (unlike what you think) the Volt engine load will basically vary the same way it varies in a regular car.
Consider that GM’s stated goal is to use the ICE to keep the battery charged at a more-or-less constant 30%. (The rationale for this has already been discussed to death.)
That means that when the battery is 30%, the car is stopped, and your foot is off the accelerator, the load on the engine will basically be zero.
As you press on the accelerator, it will use a proportional amount of electricity, which means that a proportional amount of electricity must be generated by the ICE to keep the battery charged at 30%.
Presto, the ICE load varies proportionally to how hard you’re pressing on the accelerator, just as with any other car.
There will be some small differences. Let’s say you floor it long enough to get the battery charge down to 20%. Then the engine will operate at a slightly higher load than normal (+ 15%?) to recharge the battery back up to 30%.
Or let’s say you’ve been doing a lot of braking and have managed to charge the battery up to 35-40%. That means the next time you accelerate, the engine doesn’t really have to “rev up” for a while, until the charge gets back down to 30%.
But by and large, the engine will definitely not operate at a constant load.
January 24th, 2008 at 6:41 pm
Lauckner mentions only LG Chem in this segment. And here we are Jan 24 and still no test batt from A123/Conti.
I’d love to know what’s going on with this.
January 24th, 2008 at 6:54 pm
I have to agree with AES, #38 & #39, and nasaman, #40:
If the thing won’t work the way they explain it, what’s the point? I thought that was what Mr. Lutz, et al, were saying from the beginning. The little engine runs at its optimum rpm and the speed variations are taken care of by the batteries. That’s how you get away with a tiny 3 cylinder turbo engine to move what, 2900 pounds?
January 24th, 2008 at 6:58 pm
Tom-
To answer your question about the constant load, most ICE’s operate at peak efficiency at about 3000 rpm, or about 55-65mph in 5th gear/4th gear overdrive, etc.
So ideally when cruising going the speed limit, the engine would be operating its peak efficiency. Anything lower than that, there will be surplus energy being generated, which isn’t necessarily a bad thing - it just gets stored in the battery.
Trying to create a “power on demand” situation to keep the battery at EXACTLY 30%SOC at all times is complex, inefficient, and unnecessary. There could be a “high” and “low” mode, potentially, but that magic 3,000 number should be the goal.
The only time I see the engine changing to higher speed/load, is when the battery is at borderline 30%, and there’s a heavy drain like climbing a hill, or speeding at 100mph. In that case, by all means rev the engine harder.
January 24th, 2008 at 7:19 pm
noel, #44:
Exactly, the point is not that the engine operates under constant load, it’s that it has a tiny 1L engine. It will be a full-size car with good acceleration and the fuel efficiency of a Geo Metro simply because of the size of its engine.
AES, #45:
The Volt will undoubtedly use whatever throttle position and RPM combination is most efficiency to produce the power required. Keeping the engine at 3000 RPM will be no problem if that’s what’s optimal. You can produce almost no power at 3000 RPM, or close to maximum power. This is what CVTs do, and like I’ve been saying, the Volt basically has a CVT.
Saying that surplus energy is not a problem and simply gets stored in the battery is completely ignoring everything I’ve been saying about charge rate. What you’re saying is that it’s no problem filling a teacup with a fire hose. If the ICE is producing more than just 15% over what’s required by the motor at any given time, I’d say it’s charging the battery too fast–do you disagree??
January 24th, 2008 at 7:31 pm
The A123 batteries I use in my hobby can be charged in 15-20 minutes, but that may not support the best life. I believe the 6 hours is limited by 110 VAC. 220 will charge faster, and still provide good life, I believe.
January 24th, 2008 at 7:33 pm
Then again, my batteries noticably warn on charge and discharge. They have no liquid cooling, and they are now developed specifically for this application.
January 24th, 2008 at 7:34 pm
I wish this site would support an edit…..:)
January 24th, 2008 at 7:58 pm
Jim-
I see the same phenomenon with my 6.6V pack from A123, although the only heat I ever notice is in the power electronics during rapid charge.
Whether or not charging off the ICE constitutes fast charging or not isn’t entirely clear at the moment (though I doubt it).
However, Tom’s point about the demand required by the motor (and the associated charge rate of the ICE) is essentially irrelevant because all the power is routed through the battery in the first place.
For example:
-If the car goes 65 mph and is sustained at 30%SOC by the ICE going 3000 rpm, that’s one charge rate that’s presumably OK for the battery.
-If the car goes 30mph, and the ICE still operates at the same speed/load, it’s still the same charge current applied to the battery, independent of the discharge rate. Is it suddenly a “bad” amperage/voltage simply because of the discharge rate? I wouldn’t think so.
If the batteries could not handle this type of treatment, I doubt they would have made it past GM’s selection process, much less that of the whole USABC.
January 24th, 2008 at 7:58 pm
Jim, I’ve read that charging the A123 batteries so quickly (15-20 min) reduces their lifespan to 50-100 cycles. Imagine charging your $10k Volt battery that quickly every day and having it quit working after 3 months!
I’m sure charging the Volt’s battery in 3 hours with 220V power is fine–they advertised this capability for the Opel Flextreme.
That charge rate would only require 5% of the engine’s maximum power output. Dial that up to 50% or 100% and you understand my fire hose/teacup analogy.
There are other issues with charging the battery so quickly. What if the “excess power” from the ICE charges up your battery to 50-60% by the time you get home at the end of the day. Now you can only use wall socket electricity to top it off–the economic and environmental benefit of having an “electric” car is just cut in half…
Also, what happens when the over-eager ICE fully charges the battery? Does it turn off? Only to turn back on again in half an hour? This kind of duty cycle would be incredibly hard on an engine.
The bottom line is that the simplest and most efficient way to design this car is to have the engine provide as much power as you need at any given instant, and maybe some extra if your battery is running low.
January 24th, 2008 at 8:01 pm
How about a high and low range of battery charge (a “slot charge”) and cycling the constant RPM engine of and on as needed?
January 24th, 2008 at 8:05 pm
Tom-
GM’s past series hybrids have only allowed surplus power to get up to 50%SOC (starting from 40%):
http://en.wikipedia.org/wiki/General_Motors_EV1#EV1_series_hybrid
So there’s two of your points taken care of.
January 24th, 2008 at 8:06 pm
AES, I highly doubt the power from the generator will be routed through the battery.
As nasaman has speculated, I imagine the power can simply be fed into the overall power electronics of the car. It can presumably be rectified and transformed to the appropriate phase, voltage, whatever.
If that’s impossible, too hard, or too inefficient for some reason, then I imagine the battery subsystem will be buffered with an ultracap. Engine -> ultracap -> motor means no electrochemical wear on the battery. The Prius uses two ultracaps and I imagine at least one of them serves this sort of “battery buffer” purpose.
January 24th, 2008 at 8:16 pm
I’ve speculated about using power electronics as a sort of virtual “power split” device, but rectifying voltages and currents back and forth from AC-DC, DC-DC, etc, is going to generate a lot of heat and inefficiency in of itself. (not to mention complexity)
There’s also this post from last year:
http://www.gm-volt.com/2007/08/24/new-fact-chevy-volt-generator-starts-when-battery-power-hits-50-stops-again-at-80/
“From what engineering experts in the PHEV/EV field tell me, the battery pack, electric engine, and generator are all on the same bus (not yellow or greyhound folks), which means that one can have current flowing into the battery from the generator at the same time it is leaving to run the powertrain.”
January 24th, 2008 at 8:19 pm
I think we’ve also lost sight of the fact that revving the engine appropriate to the speed of the vehicle is going to send fuel economy into the pits.
January 24th, 2008 at 8:31 pm
Tom #46:
You said, “Saying that surplus energy is not a problem and simply gets stored in the battery is completely ignoring everything I’ve been saying about charge rate. What you’re saying is that it’s no problem filling a teacup with a fire hose. If the ICE is producing more than just 15% over what’s required by the motor at any given time, I’d say it’s charging the battery too fast–do you disagree??”
That’s NOT what we’re saying and its not the way it works. Think of a conventional car’s alternator (generator), which incorporates a voltage regulator function. The way it works is to stop charging the car’s battery when it’s fully charged, and EVEN if the car’s alternator is in a NASCAR automobile racing for hours at over 200mph.
In other words, to use your analogy, the “firehose” output is turned down to a “tricle” (or entirely off) as soon as the fire is out …automatically. The point is that the generator senses the battery voltage and shuts its output off, EVEN IF THE ICE IS SPINNING IT AT FULL RPM, just as with a conventional car’s alternator & battery.
The Volt’s advantage is that its ICE can be controlled to run at a fixed rpm (+/- some small variation) INDEPENDENT OF THE LOAD ON THE VOLT’S ELECTRIC DRIVE MOTOR!!! (Sorry for ’shouting’, but I hope this helps everyone understand that the Volt’s (or any conventional car’s) batteries recharge & discharge over very long periods of time by comparison with load fluctuations. Or to use the water analogy again, a tricle from the firehose can fill a 5000 gallon tank, and if the fire restarts again, the tank’s reserve is available to turn the firehose fully on again.
In the generator/battery interface it’s all automatic & battery charge rates can vary from zero to maximum without the ICE/generator rpm changing at all. It seems what’s bothersome is that the energy available from the ICE/generator must be conserved. IT IS!!! When the battery reaches full charge, the generator output is shut off …it simply isn’t used. In other words, when the battery doesn’t need energy, the generator doesn’t supply any. The law of mass & energy conservation is fully met.
January 24th, 2008 at 8:35 pm
If the generator and motor are on the same bus, doesn’t that mean power can go directly from the generator to the motor?
Anyway, even if it can’t, my ultracap “idea” still gives the same practical result.
Can you explain why you’re so attached to the idea of a constant, ideal load? Do you know what kind of efficiency gain we’d see from that? I don’t and I’m curious. But we’re already talking about a tiny little super-efficient, turboed, (presumably) VVT engine running at optimal speed. Can throttle losses really make that big a difference?
January 24th, 2008 at 8:42 pm
Tom, the generator & motor are NOT on the same “bus” –they’re completely isolated electrically & mechanically. Sorry, I honestly don’t understand your 2 or 3 questions following that.
January 24th, 2008 at 8:42 pm
Sorry for shouting myself, but are you people DEAF?
Why (AES and nasaman) are you guys still harping about “revving” and “spinning” and RPMs?
I have said, probably half a dozen times in this thread alone, that the generator will obviously run at whatever speed is optimal. If that means a constant 3000 RPM, then fine, who cares.
RPM is largely independent of power produced. If you guys have cars, maybe you’ve noticed that, in neutral, you only have to tap the gas a LITTLE BIT to get the engine to spin up to 3000 RPM, whereas in 5th gear you have to press the pedal down halfway (or whatever).
So please, for the love of God, stop talking about RPM and let’s talk about throttle losses associated with varying load.
January 24th, 2008 at 8:44 pm
nasaman, read AES’s quote from before, which states clearly that the generator, battery, and motor are all on the same bus.
January 24th, 2008 at 8:57 pm
Sorry, Tom, what I meant is that the generator and drive motor are not continuosly connected to the battery (or bus) …the controller and/or other electronics control how much current is fed from the generator into the battery to charge it, as well as how much current is fed into the drive motor.
BTW, I never said as you quote, “As nasaman has speculated, I imagine the power can simply be fed into the overall power electronics of the car.” Sorry, Tom, I’m through trying to understand what’s bothering you & I won’t reply further on this subject. If you’re offended in any way, my sincere apologies.
January 24th, 2008 at 9:16 pm
nasaman, the thing that’s bothering me is this comment: “Like the ISS solar array, the ICE/Generator is designed to provide an essentially CONSTANT output to charge the battery”
You, AES, and others on this forum seem to think it’s very important for efficiency for the generator to provide a CONSTANT amount of power to charge the battery. I disagree completely.
Notice that the amount of power an engine produces has very little to do with RPMs, which is why I’m frustrated that everybody keeps talking about RPMs.
I just found this chart:
http://www.techno-fandom.org/~hobbit/cars/prius-curves.gif
You can see that the Prius’s engine runs at peak efficiency when it’s producing anything from ~12 kW to maximum power. (Presumably the Volt’s engine will have a similar efficiency curve.)
So actually it’s almost completely irrelevant, efficiency-wise, that the engine supply a constant amount of power. The designers of the Volt are free to run the generator under whatever load they see fit to power the car and charge the battery.
January 24th, 2008 at 9:20 pm
56 Kw engine. 16 Kwh battery. if the load goes to 0, the battery would be charging at 3.5C. This is in-spec for an A123, but yes, it will likely effect life. A battery which is better than an A123 that I know would help. Also an ultracapacitor may help, but I think it will have to be big…..not sure.
Well, yea Tom. I dont know much about engines, but if it is running at a certain constant rpm, it doesnt have to put out its full rating does it. If we want to charge the battery at 1/2 C, say, then the generator will reflect an 8 KW load ( more or less, neglecting efficiency loss ) on the engine, so the throttle goes back to regulate the rpm to the set charge rate.
There are a number of variables here. I may be missing something, but I am thinking it will work….
Cool….
January 24th, 2008 at 9:27 pm
Well, its just that if the engine runs at 3000 rpm with minimal throttle….I guess it can put out next to no torque. The throttle is just set to offset the friction in the engine. if there is a load, like charge maintenance, or acceleration load on the electric motor, then the throttle increases. Transients are supplied by the battery…..something like that.
January 24th, 2008 at 9:46 pm
Jim,
I think you’ve hit it. I don’t think the engine rpm will chase the throttle.
January 24th, 2008 at 9:48 pm
Yes, exactly, Jim.
I think the simplest thing to do would be draw as many kW as necessary to power the car’s motor, accessories, etc., and add on ~8 kW to charge the battery if it’s < 30%.
This would cause the car to sound like any regular car with a CVT. Hit the gas and the engine produces more power (and gets louder) immediately. Let off the gas and the engine gets quieter immediately. Of course, it will still drive exactly like an electric car on battery power because the engine isn’t connected to the wheels.
You COULD have a “fuzzy logic” algorithm that keeps the battery charge between, say, 30% and 35%, so hitting the gas for 10 seconds would just cause the engine to get somewhat louder for the subsequent 2 minutes. I don’t think there’s any efficiency advantage to that, and it may wear out the battery depending on the result of this whole power bus/ultracap debate, but it may sound/feel cooler.
January 24th, 2008 at 10:01 pm
you guys is smart
January 24th, 2008 at 10:48 pm
Michigan now bans foreign nationals to get driver license and treat every non-American as illegal immigrants. this is stupid and will prevent any talents (does Michigan have too many to compete with Toyota) from coming, and sooner or later, GM/ford/Chrysler will die!!! And I think it is a good thing if their government and state is so stupid due to fear of globalization, Michigan tell wetbacks, chinks, Japs (ought to be killed), gooks, limeys, canadians: go back to your country and make sure you support us by buying our junks!
January 25th, 2008 at 12:48 am
LOL — you guys are killing me by making this so difficult, but I am enjoying the argument!
For heaven’s sakes go rent a house boat with a diesel generator. The diesel powering the generator runs at constant rpm. Start up the generator and turn off shore power. With all the power off the diesel has no load and the throttle position is just above idle. Turn on the oven, air conditioner, stereo, etc. and boom the generator is under electric load. The RPM may drop momentarily as the throttle position changes to force more fuel into the cylinders to account for the electric load, but quickly returns to the same constant RPM. The only difference is the diesel is louder due to higher fuel consumption. The Volt ICE at constant speed would work in the exact same fashion. If the house boat industry can figure it out, I’m sure GM can too – or they can subcontract.
Keep in mind that a HP – RPM curve shows the maximum HP available at any RPM at wide open throttle. Less HP at a give RPM is also possible. So at 3000 RPM the engine may be able to generate 60 HP at wide open throttle, but at 10% throttle and 3000 RPM it could only be generating 6 HP (assume a linear response). So in other words, a 3000 PRM power setting may be able to handle the load required by the electric motor and batteries 98% of the time. The other 2% of the time a higher RPM may be required to generate more HP at WOT (i.e., flooring the accelerator with < 30% SOC in the batteries).
January 25th, 2008 at 1:46 am
Rooster,
One difference will be that the Volt Ice will respond quicker/better to a duty cycle call w/needed HP because the engine is blown.
January 25th, 2008 at 6:21 am
Shame GM can’t gives more details yet so everyone could quit assuming final design and we could just “get along.” I imagine they aren’t far enough along in design yet to say how components will be used or what they are. Though, it would be nice to hear a little more about what the possibilities are rather than a “two-step.”
As far as constant generator power vs variable goes, they probably haven’t decided this yet. Maybe it’ll take mule testing to sort this out. Though, from previous posts it sounds like their leaning toward varying generator output. Likely, they’ll optimize ICE and control for a peferred power but have to vary output some.
I just hope that they don’t take the needs of TOO many over the needs many. I hope they don’t lose sight of the goal (like some postings have) to maximize EV miles from external energy. By this I mean, APU should kept as simple, inexpensive, and reasonably efficient as practically possible. Do not optimize design for 100+ mile/day drivers. Until battery packs get more range, those drivers will be best served by a parallel hybrid. There is just no good way around the 2 extra energy conversions.
My druthers would be ICE optimized for most efficient output while still being able to climb a mountain pass at good speeds.
For those concerned by high rate of charge: if specs call for battery capable of maintaining 25KW discharge for regular use, why would 25KW charge rate be an issue?
January 25th, 2008 at 8:22 am
E85 continues to trouble me. The current stampede to produce corn-based ethanol will drive up feed prices for animals and food prices for humans. I understand that the corn needed to make 25 gallons of ethanol would feed one person for an entire year.