We have been discussing the cost of operating the Volt. In particular I have focused on what the electric cost will be to drive the first 40 miles without gas (or E85). We knew the battery holds 16 KWH of energy, but it hasn’t been clear how much of the battery would be discharged by the end of the first 40 miles of driving. We didn’t know at what battery power level the on-board combustion generator would kick in. Commenter’s here and myself have given our best guesses…
Well it’s official folks, I have heard back directly from GM sources, and the answer is 50%!
This is big financial news and very cool. It means that the Volt will only requre 8 KWH of power to drive the first 40 miles.
This translates to a cost then of 8 X 10.65 cents (U.S. avg) or $0.85 to drive those 40 miles!
It also means, if you wanted to, you would only have to generate 8 KWH of solar power to charge the car. That’s five 200 W panels getting 8 hours of sun.
GM spokesperson Rob Peterson also points out that the average commuter who drives 40 miles per day uses 500 gallons of gasoline per year. Multiplied by every user of the Volt, if the car becomes widely adopted, U.S. gasoline consumption could be decreased substantially.
This entry was posted on Friday, August 17th, 2007 at 5:49 pm and is filed under Battery, Electric Motor, Engineering, Financial, Fuel. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.
Aug 17th, 2007 (6:02 pm)Lyle, excellent information! I’m wondering if this will also effect the 7000 charge cycle life that the A123 cells have been reputed to have. If that were increased through limited discharge and charge cycles, then the useful life of the vehicle looks better and better.
Aug 17th, 2007 (6:40 pm)Hi All, I have this feeling that in future, people will talk about mileage of vehicles in terms of miles per KWH (something like MPK, instead of MPG). So write now Volt is 5 MPK (40 miles / 8 KWH). And it make a lot of sense to me since a large SUV like Tahoe might be able to run 100 miles between two recharges, but that would not mean that it is more efficient since it will use more electricity for recharging. Once EVs are popular, then the next step would be, companies advertising that there new auto is giving 6 MPK, 7 MPK etc
Aug 17th, 2007 (8:26 pm)Excellent work, Lyle.
Last time I looked at DOE stats, the national average electric rate was 8.5 cents, which is what I pay in Florida, and
my friend pays in Virginia, making that 40 miles jaunt 68 cents, versus $6.00 for gasoline (non-highway). Almost 10 to 1 savings. They keep claiming 5 cents in California overnight, or penny per mile.
Now who was that claimed EV driving doesn’t
save money?
Aug 17th, 2007 (8:53 pm)Look for employers to install 110V outlets in their employee parking lots. Their
average employee’s car would probably only need 45 cents worth of electricity to completely recharge. I very inexpensive way to provide an appreciated employee benefit.
Aug 17th, 2007 (9:15 pm)Forty miles for 8 Kwh sounds great. Affordable even for people in the San Francisco Bay Area who are on PG&E.
When can I get my Volt?
Aug 17th, 2007 (9:37 pm)Great information Lyle. Thanks!
The Volt is looking better with every report. I can hardly wait!
Aug 17th, 2007 (10:24 pm)For the average 12000 mile per year driver that’s only 2400KWh per year. I managed to save about that much by energy efficiency measures alone. I replaced inefficient equipment, like incandescent lights, old pool pump (for variable speed), old computer UPS, and a few more measures. So if you can find some efficiencies then you can drive your Volt for free!
If you run an old 1HP single speed pool pump for about 6 hours a day, that alone will use about 8KWh per day. So you could run your car for less than the cost of your pool!
As for powering by solar, to generate 2400KWh in New York (Long Island) you will need about 2.2KW of panels. In southern USA you will need a little less. That could cost as little as $6000 with utility rebates and tax credits.
As for the original post saying 5 x 200 panels, unless you live on the top of a snow covered mountain on the equator, you will not average 8KWh per day from 1KW of solar panels (although you might get that on a good day). You could move to live on Mount Kilamanjaro
As for my Volt, it will be powered by solar.
Aug 17th, 2007 (10:34 pm)I think that 4 to 5 miles per KWh is about what the Tesla is going to get.
Aug 17th, 2007 (10:55 pm)This idea of mpg as a measurement of efficiency is archaic. That is because there is a much bigger delta in fuel usage if you lose 5 mpg in a 10mpg car that if you lose 5 mpg in a 100 mpg car. Since we are talking about changing units, then I believe we should change to KWh/mile. In the case of the Volt described above it would be 0.2 KWh/mile.
In the overview of reasons for owning a VOLT, global warming was deemphasized. It is important to point out that, even if the VOLT batteries are charged using energy from coal, the resulting CO2 emissions are 20-40% less than a conventional car. This is because the overall well to wheel efficiency is substantially greater using a modern power plant and an electric car.
Also, of course, it is only by converting to the power grid that we can ultimately use pure renewable energy sources such as solar and wind. Currently, for example, windmills are shut down in the middle of the night because nobody needs the power.
Aug 18th, 2007 (12:49 am)I doubt EVs will get to the point where they are using less energy than it takes to make them move.
So ‘miles per kWh’ isn’t going to vary much.
The reason is, electric motors only use as much power as is needed for the demand at the instant. This is a good thing, since relatively little power is wasted. Some motors will likely be a little more efficient than others.. but probably not much.
Aug 18th, 2007 (1:04 am)Let me know when you’re ready to buld your solar systems to charge your Volt! Solar Carport for direct demand with battery back-up or my forte Solar tracking systems for grid-tie that allows your electric meter to run backwards during the day and charge your Volt at night. It’s the American way.
Aug 18th, 2007 (7:59 am)50% seems quite high, as one of the positive characteristics of the A123 battery is deep discharge cycles. Perhaps it will have a button, an EV only mode, that allows a deeper discharge before the gen-set kicks in.
Second, I doubt if the overall EV mode mileage will be 5 MPK or .2 KWH per mile.
In field tests the average performance which includes being stopped in traffic with the AC and auxiliaries running (radio, SatNav, etc) the mileage runs closer to .30 KWH per mile or about 3 MPK. So if the discharge started at less than full charge and stopped at 50%, only about 7 KWH would be available for a range of about 23 Miles. Hence, I think to reach the 40 Mile performance, the battery will be discharged down to around 20% of charge
Aug 18th, 2007 (8:26 am)Where do I line up to get one? My wife can have the Prius, I’ll be styling in this thing!!
Aug 18th, 2007 (11:31 am)I went to eat with my family yesterday and I told them about the volt. We’ve always had large GM cars and my brother thought the hybrid gas millage was an exageration, but they opened up to the fact that where the volt is going is where we all should be going with cars. Electric plus range extender. I think it’ll only be a matter of a few years before the rest of the people in the USA catch on to this fact.
The fact that we can win the war on terrorism just by changing the kind of car we use. What did bin ladin say, this war would keep going on for many decades into the future, we’ll see what he says when he has 50 cents in his bank account.
Aug 18th, 2007 (3:46 pm)The marketing was that if you can keep your miles below the 40 miles maximum “you may never use a drop of gas”. If drivers want their batteries to bottom out on their way back from their commute, that’s their prerogative. So there better be a way to disable the 50% cutoff. If there isn’t, I can see people installing a killswitch in frustration.
Aug 18th, 2007 (4:25 pm)I am confused. So this means the actual ev range is 80 miles if dont put gas in it?
Are you sure that this doenst mean that the generator kicks in after 20 miles?
Aug 18th, 2007 (5:31 pm)I’m cool with only using half of the battery capacity before turning on the generator. It’s nice to know that the Volt will only use this much electricity, too, in order to get the 40 miles. What I want to know, though, is if there going to be a shallow-discharge only mode that will turn the generator on at 10% discharge for long trips so that the remaining electricity can be used in case I run out of gas. Does anybody know if it’ll include such a feature?
Aug 18th, 2007 (7:36 pm)I agree with voltman, this doesn’t make sense.
What exactly was GM asked and how exactly did they respond?
Aug 18th, 2007 (7:54 pm)This is great information. My concern is will GM will ramp up production to meet the incredible demand for this product so that we don’t have to wait in line for several years to obtain one. Perhaps we should be buying GM stock now.
Aug 18th, 2007 (8:03 pm)Why not a full EV mode on Volt with a 80 miles autonomy !!!
Aug 18th, 2007 (8:07 pm)I’ll be installing an aero cartop solar trickle charger ASAP. And, my electricity is wind sourced because we already pay the “Green Premium” for wind power on our monthly bill. My numbers show that getting a Volt that’s painted white (instead of black) will increase my range by 10% (i.e., cooler interior = lower interior temps = can run the AC at lower setting, or turn it off).
I will pay $1,000 today to get in line for one of the first Volts off the assembly line. How can I sign up to be a beta tester?
Aug 18th, 2007 (8:23 pm)To clarify any confusion..
What this means is that it will only take 1/2 of the Volt’s fully charged battery pack’s power to drive the car for 40 miles. This is better than it requiring all of the battery’s stored energey to do so.
Another way of looking at it is that it will only require 8KWH of energy (as opposed to 16 KWH)to drive for 40 miles. This means it will cost only 85 cents (U.S. avg electric rate of 10.65 cents.
It wasn’t clear at first how much of the battery’s discharge would be needed to go the 40 miles, the 50% mark is brand new information direct from GM.
Hope that helps.
Aug 18th, 2007 (9:08 pm)Using 100% of the battery before engaging the generator is a very bad idea as far as battery life is concerned, this causes batteries to fail much earlier. From everything I’ve read most battery chemistries shouldn’t be discharged more than 80% or battery life will be significantly reduced. I would imagine that that they choose 50% as a trade of to ensure long battery life. Now would it be possible to safely use more than 50%, most likely, but you wouldn’t ever want to completely discharge. And you never know GM may revise this figure if longer term tests show it can reliably be increased.
Aug 18th, 2007 (9:50 pm)I don’t know where I got this idea. But it was my impression that you could put the generator in “Automatic mode” and it would just come on to keep the battery charged. But had always thought that you could turn it to manual.
Lets say you work 19 miles from work. On your way home you would know that you will have enough power to make it home and would not want to use gas so you would leave it in manual mode. Otherwise you would be using gasoline all the way home to recharge the battery when you would not want it to.
If they just told you that the generator would come on at 50%, that doenst necessarily mean that you can go 40 miles on that.
Aug 18th, 2007 (10:14 pm)That’s good news.
Now we need to get a MINIMUM oil and diesel fuel price established in America, to help motivate Americans to buy a Volt. Once demand drops a bit, the cost of gas will drop in response, we can not allow that to happen. ONLY if the cost is held high will people move away from it. You can talk about global warming until you’re blue in the face, but some people will never care. It’s the financial perspective that will work the best. “Drive electric because it’s cheaper.” That’s the answer.
We need to get started on this now since it will take years to get congress to take action.
Join the Jihad against oil: http://www.oiljihad.org
Aug 18th, 2007 (11:01 pm)GM has been very adament about the fact that they wanted about 40 miles before the generator kicks on. 50% discharge does equal 40 miles.
I would bet a ton of money that the 50% generator kick on will be something that isn’t easy to override.
Why? This is the first vehicle of its kind. (not really but to the general public will be.) GM is doing its best to hit a home run. Having people kill batteries earlier than they should would be very very bad press for this type of vehicle. GM is going to try to make this vehicle as safe (battery wise) and as idiot proof (battery discharge wise) as possible.
Any change to the discharge bottom limit will be an after market thing that voids the warranty.
On another note with regard to the MPG vs MPK, I vote we stick with MPG! Then I can say I get 1000000 miles to the gallon.
Aug 18th, 2007 (11:13 pm)Omega… I think the BEST rating for the Volt will simply be COST PER MILE.
I would love to see some sort of computer in the Volt that could track how much power it’s consumed and spent, and how much fuel has been consumed.
Aug 19th, 2007 (12:05 am)I can think of two reasons for choosing 50% to kick on the generator.
1) One is the battery life issue that some have already mentioned.
2) The other is a performance “safety factor”. They need to leave enough extra energy that even under extreme conditions (using energy faster than the generator can make it), the batteries will not be depleted. If you start running on the generator alone, the Volt is then running at one-third its normal horsepower. That could be bad. For example, suppose you have to drive fast in an emergency situation, but then discover you cannot. This actually happens sometimes. I suspect car reviewers will probably also test for this. And they will probably ding the Volt (relative to an ICE vehicle) if GM allows the power level to drop.
Aug 19th, 2007 (1:41 am)Excellent point. I never heard any stats on the volt running vea just the generator.
So does anyone know. Does the battery continue to drain as you drive past 40 miles?
Aug 19th, 2007 (9:35 am)Control of the “range extender” NEEDS to be tied into an onboard GPS trip computer so that ONLY enough power is produced onboard to safely reach the NEXT charging opportunity. Simply punch in your trip destination(s) and indicate where opportunity charging is available.
If the next charging opportunity is greater than 40 miles or 50% of discharge, the “range extender” will ONLY charge the battery with enough energy to reach THAT destination without fully charging the battery. The battery SOC (state of charge) can then be “topped off” via electricity import. This will maximize “opportunity charging” and significantly reduce onboard “range extending” fuel usage.
I’m sure that hackers will be able to adjust this “state of discharge” for a greater pure BEV range, however this will most certainly void GM’s warranty of this very expensive battery pack. Individual risk tolerance varies.
Aug 19th, 2007 (10:30 am)Paul makes a good point that I had not thought of – when the battery is ‘discharged’ and the generator kicks in, having some juice left in the battery will be a good thing, because the generator doesn’t put out enough power for peak demand (stomping on the throttle)
Omega, relating to what Paul wrote, I believe it would be like this: You hit about 40 miles and the generator kicks in, then for whatever happenstance, you HAVE to STOMP on the throttle. The generator doesn’t put out enough juice to accelerate as fast on it’s own, so it draws some juice from the battery. Situations like this would likely only be momentary, so the overall drain on the battery likely wouldn’t be too bad.
Tim, I’ve thought about a couple different ‘modes’ the Volt could be set to.
One would be a sort of ‘conservative’ mode, where the generator would only run as long as it absolutely needed to – meaning if you drive say 45 miles to a destination where you’ll be able to plug in, the generator would kick in for the last few miles, then shut off when you shut the vehicle off.
Alternately, there would be an ‘aggressive’ mode, where the generator would run until the battery is fully charged, regardless of whether or not you stop and shut off the vehicle. This second mode may be useful for when you’re driving somewhere just at the range of the Volt, but won’t be able to plug in.
Given the generator puts out the same amount of power whether you’re driving, or stopped, it would run for a shorter amount of time if all of the power it was generating was directed to the batteries. Charging while stopped would use the least amount of fuel to achieve a full charge.
I also think there should be a ‘top off’ option, where you could get to a destination and set the vehicle to charge until topped off. This would be the user’s choice based on how much range is left, and the demands of their driving at the time.
As an aside, I calculated it would take about 9 minutes for the battery to recharge from the generator, as long as there are no other demands on the power. (53kW from the genset, 8kWh to a full battery)
Aug 19th, 2007 (11:06 am)Questions for Lyle,
I understand the 50% discharge before the generator kicks in. Am I right in assuming the generator only charges the batteries to keep the Volt running? Say you are driving on a trip (interstate doing 65mph). Will the generator be able to fully recharge the batteries while driving and return to full electric mode while still traveling. Example: 40 miles electric, generator till recharged (? miles), 40 miles electric?
Aug 19th, 2007 (11:26 am)StevenT,
You are correct, when the generator kicks in, it divides it’s output to moving the vehicle and charging the battery.
The generator’s output is constant (rated at 53kW), and whatever is not used to move the car goes into charging.
So if you drive, and keep driving, the generator will turn on and run until the battery is charged, then shut off, and you keep driving like nothing’s happening.
Aug 19th, 2007 (12:21 pm)Thanks Matt986,
I guess my next question would be if GM states that the Volt gets 50 mpg in generator mode wouldn’t that extend your range on a trip by more than 640 miles if the generator periodically goes on and off after recharging the batteries so you drive an additional 40 miles electric? 12×50 for gas plus 40 miles x ? recharges? What could be the hypothetical range?
Aug 19th, 2007 (2:00 pm)I am not sure about whether the generator splits it’s output to the electric engine and the battery. I thought of it being more likely that the generator is only there to charge the battery on the fly, once it hits 50% SOC, so that the electric engine is only receiving energy directly from the battery.
What is your source on this Matt986?
Aug 19th, 2007 (3:32 pm)Lyle,
My source is sitting on my shoulders.
IMTO, regardless of where the power is coming from to drive the motor, the generator puts out X amount of power, and would take Y amount of time to charge the battery, plus time to compensate for what energy is used during the time that the generator is running.
So, if the generator’s power goes directly to the battery, but the motor is drawing power from the battery at the same time… it’s really effectively pulling it from the generator.
Aug 19th, 2007 (3:41 pm)Here’s how I think it will be laid out:
There will be a controller with four things connected to it -
Battery
Motor
Generator
Charging input
This controller will control the flow of current depending on what is happening. Battery -> motor makes the car go. Motor -> battery during regenerative braking. Generator -> battery for recharging.
When I mention that power the generator is generating will be divided between the motor (making the car go, or stay at speed) and the battery is this -
Current couldn’t be simultaneously going TO and FROM the battery.
Given this setup, while cruising, the generator would be the source for power to the motor and for charging the battery. Under heavy loads, current would be drawn from the generator AND the battery.
Basically, current can only go one direction with regards to the battery.
Aug 19th, 2007 (3:50 pm)This is a very good discussion. Like to get more clarification from GM. Only they may not have all the details until they start road testing first of next year.
My question and desired behavior is the following. If I drive 50 miles in one day. I would drive first 40 miles on electric, then generator kick in. I only want it to recharge for me to get home and complete the 50 mile trip and not to fully recharge to 100%. What I do not want is to get home and have the battery fully recharged by the generated because I traveled more than 40 miles. Want to plug in and recharge as much as possible at home and not from the generator.
Like other commments need different modes. One, fully recharge to 100%. Two, recharge only to 60% or so to continue to drive, like maintenance mode.
Aug 19th, 2007 (4:46 pm)Additional question for Lyle,
Check with GM how the the generator will impact the lifecycle of the battery. For example, you have to travel 80 miles in one day. First 40 miles from overnight recharge from plugin. Second 40 miles from generator charge. That would be two cycle of the battery. What happens if you only travel 60 miles? When the generator recharges the battery, is that another cycle of the battery? Having just a particle recharge could have bad impact on life of battery and so GM may require the recharge to be close as possible to min (50%) to max (100%) recharge as possible to max the life cycle of battery. Next time you talk to GM this would be good to better understand.
P.S. Thanks for all the recent updates you have been providing.
Aug 19th, 2007 (4:52 pm)Partial charge cycles should not cause any problems as Lithium chemistries do not suffer from memory effects.
Aug 19th, 2007 (5:04 pm)The energy used per mile does not depend on the particular electric motor used, it depends on how much energy is used to move the vehicle. Rolling and air resistance primarily, and accelleration requirements.
I hopet the charger only charges to 50% so I can plug in charge.
Aug 19th, 2007 (7:27 pm)Obviously we don’t know. We need answers Mr. Website owner!!! Looks like you need to annoy the GM folks again.
I would suspect that the battery will never rise much past a 50% charge once you have gone past 40 miles.
I can envision two possibilties.
1. You drive for 40 miles and then the generator is used to power the car and charges the batteries when the car is coasting or stopped. This will allow the car to drive until it runs out of gas at 640 some odd miles.
2. The generator kicks on at 40 and continues to assist the batteries which will continue to draw down to 30% discharge at about 640 miles, at which point the car will have to be recharged partially before travel can continue.
The battery will actually be made of many cells and some could be charged while others are discharged on a rotating basis if charging will discharging is impossible.
Aug 19th, 2007 (7:43 pm)Omega – one reason for multiple smaller cells is getting a larger amount of current by drawing from many at the same time.
As for your #2, it wouldn’t work that way. Say you get on the freeway and just start going. You hit that 40 mile mark, and the generator kicks in. This supplies 53kW, which, at constant speed, is much more than the car needs. The extra power is directed to the battery. The generator runs until the battery is charged. (One snippet I saw posted from GM somewhere – at 70mph, the generator would have to run for about 30 minutes to fully charge the battery pack)
Aug 19th, 2007 (7:48 pm)Stormc has a good point – electric motors are very efficient when cruising. They only use the amount of energy needed to keep the vehicle moving.
What DOES factor into to how much power is used are things like:
Vehicle mass (inertia)
Rolling resistance
Wind resistance (drag)
So generally smaller, lighter and more aerodynamic vehicles require less power. They will be the most ‘efficient’ per kWh used.
Aug 19th, 2007 (9:01 pm)Great Discussion, a lot of unknowns yet.
I can see that once the 40 miles have been driven, the generator kicks in at 53KW, and as Matt points out, too much juice to power the car so the battery gets charged simultaneously. I don’t think the battery will get topped off though, prob stop around 95% (if you drive that long) then will shut off again. For long drives, on/off, on/off, until gas gets low. This won’t count as a full deep discharge towards the batteries lifecycle.
Aug 19th, 2007 (9:18 pm)The Volt’s generator is pretty high power if it can recharge the Volt’s pack in only 30 minutes. Comparing that to a 6 hour charge from your wall plug, that’s 12X the power. That’s a lot of power!
Under normal real-world driving conditions, I would bet money that the charger will recharge the Volt’s pack back to 100% in about an hour( even while driving), then it will shut off for the next 40 miles or so. However, if you’re racing your Volt up Pike’s Peak, the generator may run continually and struggle to keep the battery charged above 50%. Just like an ICE vehicle, your range and mileage (aka power usage) will vary greatly depending on how you drive it.
Lastly, it’s my understanding that with lithium-ion batteries, a 50% discharge followed a 50% recharge only counts as half a cycle against the 7000 cycles that the pack is rated for. You pay no penalty for partial cycles.
Aug 19th, 2007 (10:00 pm)If the generator can charge the battery in an hour or less then apparently the generator only runs intermitently after the initial 40 miles. And if the idea is to save gas then maybe it cycles between like this:
50% turn on generator!
65% turn off generator!
50% turn on generator!
It would be stupid for the generator to keep running to get a full charge when the idea is to ‘not use gasoline’. Better to cycle the generator periodically which give you no change in performance and to allow you to keep the batteries near 50% so that you can charge more cheaply with electricity instead of gasoline.
Aug 20th, 2007 (1:56 am)Omegaman, that\\\’s how I expect the charge-sustain mode to run under normal circumstances, but probably with a lower threshold for recharging, though. My guess is that it would be enough for no more than 5 more miles of driving. What I\\\’m interested in knowing is if there would a button for use on long trips that would put the charge-sustain threshold higher, like enough to run the Volt for another 35 miles without using the ICE. I like that idea, and I think it work well for cross-country driving, as long as the button has to be pressed each time the car is turned back on, like when stopping for a meal or other kind of pitstop when driving. Any opinions?
Aug 20th, 2007 (10:24 am)Guys, you need to realize the reason for only using half of the battery’s full capacity is for the longevity of the cells. I don’t think GM will allow a deeper drain on the pack for any reasons. Sure, range is a good thing, but not having to replace a whole bunch of battery packs under warranty because they were too stressed is better for their business. I’d rather have a battery that lasts me for years of use, than one that can get me a few more miles.
We really need to think of the Volt like this:
For trips under 40 miles total, or trips where you can charge up at your destination – the Volt is a BEV.
For longer trips, it’s a serial hybrid.
That’s it.
I think the only way one should be able to defeat the generator would be to stop and shut the whole vehicle off. Although letting it run when stopped (when you can’t plug in) will run the generator for less time, using less fuel.
And I already calculated guys – the generator would have to run for about 9 minutes to generate 8kWh of power. That means with no other load on the generator, it would charge the battery in about 10 minutes.
I’d bet money that the Volt will drive as such: You go ~40 miles, and the generator kicks in. You keep driving, and the generator stays on until the battery is charged, then it shuts off, and you get about another 40 miles. Repeat until you stop. It’s simple, and it keeps the cycling of the batteries uniform.
Aug 20th, 2007 (3:39 pm)Why not be let a computer manage the recharge cycle based up miles to go to plug in for a full recharge? Could even hook it up to a GPS nav system.
Aug 20th, 2007 (5:34 pm)Ron,
That would probably require too much input from the driver. That’s not a ‘get in and drive’ solution that everyone is used to.
One would have to stop and think… “is it 57 miles or 67 to Bob’s house? Should I tell the car it’s 67 to be safe?”
Having the management be tied into GPS would be easier, but again, still requires a lot of interaction. If you just want to run to the store, or across town to a destination you’re familiar with, having to program the car every time you get into it would be cumbersome.
I think just a couple modes would be the easiest solution. One mode that aggressively uses the generator to charge the battery, one that is passive which will limit the use of the generator and shut it off when the vehicle is shut off.
We have yet to see how GM will manage the system, but the design leaves a bit of flexibility, that’s for sure!
Aug 22nd, 2007 (9:06 am)Matt,
Including a Trip GPS tied to the “range extender” control is a no-brainer. Trip GPS is cheap and available in many car models today. This system will make sure that the “range extender” only provides enough electricity to reach the next off-board charging opportunity. I have trip GPS and it would only take about 30 seconds to punch in a destination address and indicate if opportunity charging is present. That’s less time than it takes to warm-up your current ICE.
Will it save fuel and money when used? YES.
Will everybody use it? NO.
Will most buyers want it? YES.
Will most volt divers use it to save more fuel? YES.
I LOVE my Trip GPS!!! Once you use it, you’re hooked!
Aug 22nd, 2007 (9:56 am)keeping the car at 50% charge makes sense i guess. but why have that extra 8kwh of battery if you are not going to use it.
I understand that you dont want to fully discharge the battery but 50% seems like overkill. 20% seems more reasonable. According to the a123systems.com website, their batteries can handle deep discharges anyway.
Aug 22nd, 2007 (2:47 pm)Matt986 sez:”I’d bet money that the Volt will drive as such: You go ~40 miles, and the generator kicks in. You keep driving, and the generator stays on until the battery is charged, then it shuts off, and you get about another 40 miles. Repeat until you stop. It’s simple, and it keeps the cycling of the batteries uniform.”
If this is true, then you would never plug it in. It is more likely that the generator cycles on and off to keep the batteries at 40% to 60% capacity. Having the on board genset fully charge the batteries would defeat the purpose of the system.
Aug 23rd, 2007 (10:23 am)Well, you guys gotta realize that with the stated range of battery ‘discharge’ at 50%, it doesn’t mean the battery will get charged to full (100%) and then only discharge to half full (50%).
It will likely do what hybrids do with their batteries: Charge to about 80% of the ‘full’ capacity, and only discharge to about 30% of the ‘full’ capacity. That’s 50% of the total capacity of the battery.
So if you’re looking at the range of the battery compared to 100% full, the battery would start out ‘charged’ at about 80%, then you’d drive. At about 40 miles, the battery would be at about 30% of ‘full’, and the generator would kick in and run until the battery is ‘charged’ at 80% of ‘full’.
Keeping the battery from going to 100% charge and 0% (completely depleted) allows for a longer service life for the cells.
So don’t confuse the 50% to mean that the battery will only charge to 50% total capacity, or that it will charge to 100%, and then only discharge to 50%.
We haven’t seen specific numbers yet, but I can bet that the ’50%’ usage will be between completely discharged, and completely charged.
Ya follow?
Aug 23rd, 2007 (6:29 pm)Matt, no matter what the recharge min and max are, if a computer were to manage the recharge cycle based upon the miles to go to a full plug in recharge, you could always arrive home with a charge level that would allow maximum use of the 110v plug.
Aug 27th, 2007 (10:43 pm)ug Says: “Here is how you beat the lack of a kill switch with no hacking required. Just don’t put any gas in it, period. Do you think they are going to make the car stall at 50% battery capacity??”
No, I’d expect an idiot light to come on and a chime announcing “Out of Gas, please refill at the nearest available station”, repeating over and over til you nearly go bonkers. If you ignore that advice, then around about 30% SOC, the car goes quiet and shuts down to protect the battery from excessive discharge. Then your choices are: get a tow, get a charge (if power is available) or get some gas and restart the car.
But why pack around an engine and tank if you never plan to use it? There will be regular battery electric cars available, GM might even decide to offer a “battey only” version of the Volt.
Nov 5th, 2007 (6:23 pm)Nobody seems to be mentioning the fact that these packs by law must meet very high warranty standards, namely 10-years/150,000 miles, at least in CA and a half dozen other green states here in the Northeast. It’s therefore essential the packs be babied, and a 50% DOD is plenty IMO.
The Panasonic EV NIMH packs used in the Prius vacillate between 60-80% capacity, that’s IT, a pretty narrow window but it works, and Toyota has had close to zero problems with their packs, even on the oldest cars.
Separately, it is just as important not to recharge much above the 80% level as you must allow “room” for the regenerative power to go should the car encounter a long downhill and a lot of braking. It will be interesting to see the limits GM sets on its packs on the upper end given this is a serial hybrid and very different from the Prius.
Nov 19th, 2007 (10:36 pm)OFF TOPIC MALIBU FAKE HYBRID COMMENT: GM LOST 39 BILLION LAST QUARTER AND THEY DEPRESS ME WITH THIS HOAX HYBRID MALIBU THAT ONLY CUTS OFF THE ICE AT A STOPLIGHT TO CONSERVE FUEL AND THE BATTERIES ARE USED TO RESTART THE ICE QUICKLY AFTER YOU APPLY THE THROTTLE. GM ALSO LOVES THEIR CUSTOMERS SO MUCH THEY REFUSE TO POST A EMAIL ADDRESS FOR COMMENTS LIKE THIS. GM IS TRYING HARD TO BANKRUPT AND GET A GOVERMENT BAILOUT IT SEEMS IN THE VERY NEAR FUTURE. ALSO DID YOU GUYS KNOW THAT THE SAUDI’S HAVE BOUGHT OUT GENERAL ELECTRIC PLASTICS DIVISION WITH IT’S HUGE PROFITS THEY ARE GETTING FROM US ON GASOLINE SALES. I SAY, SAY NO TO GM UNTIL THEY SELL A REAL CAR WITH A REAL FUTURE FOR US AMERICANS BEFORE THE SAUDI’S OWN ALL OUR AMERICAN COMPANIES.