Aug 29

Latest Chevy Volt Battery Pack and Generator Details and Clarifications

 

batterysocmode.jpg

In some recent posts, we were able to find out and discuss some important details about how the Volt’s li-ion battery pack is intended to function. One of the most critical facts we obtained from GM is that the 40 mile all-electric driving range will occur within 50% of the batteries maximum charge, or 8 kWh out of 16 kWh total. This translates to 200Wh/mile of energy consumption.

We also looked at the ability of the combustion engine (53 kW maximum) to keep the battery charged and how it might operate to do so. This generated some very intriguing discussion and further questions.

I went back to GM and had some discussion with other sources familiar with the Volt’s engineering, and have been able to elucidate the following more accurate facts:

As per Rob Peterson, GM spokesman, the battery will operate in the 50% “swing” zone, but actually, the batteries full point will be 80% (not 100%). So its charge state will actually vary between 30% SOC and 80% SOC. This translates to the following analysis of battery capacity:

theoretical capacity         100%                16.0 kWh (not realized under normal conditions)

highest recharged level     80%                 12.8 kWh (after being plugged in)

charge sustaining level     30%                  4.8 kWh (after ~40 miles of driving)

empty                             0%                    0.0 kWh (not realized under normal conditions)

In terms of the on-board generator, the peak power of 53 kW will rarely be used, only in extreme conditions. Peak efficiency 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.

The engine’s job will be to maintain the battery at a SOC of 30%, and will do so by continuously matching the average power requirement of the car once it is turned on.  Those energy requirements will roughly be about 8 kWh in the city, and 25 kWh on the highway.

Another interesting note is about the time course of recharging the battery on the road. If one tried to recharge it by maxing engine output, the cells’ temperature would get too high, so the idea of rapidly “refilling” it on the fly and then cutting off the generator wont apply. Rather, it seems, the engine will continue to run, constantly matching the needs of the car to keep the battery at 30% until you stop driving.

Interestingly, the motor will likely be programmed to increase rpm when you step on the gas and quiet down when you stop to “simulate” the driving effect people are already used to. This will avoid the sudden unexpected ons and offs.

The graph above illustrated how the pack shall operate.

This entry was posted on Wednesday, August 29th, 2007 at 8:35 am and is filed under Battery, Design, Engineering, PHEV. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

COMMENTS: 57


  1. 1
    Nick D

     

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    Aug 29th, 2007 (9:40 am)

    Thanks for clarifying that for us, this will allow us to maximize the amount of grid energy that the car uses. I dont know if it is the most efficient use of the engine but it makes the car a lot more user friendly for the average driver.


  2. 2
    Questions

     

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    Aug 29th, 2007 (9:44 am)

    I hope this won’t engender more complaints.

    However it works, I will be happy.


  3. 3
    Mike756

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    Aug 29th, 2007 (9:50 am)

    Does this solve the issue of long down hill braking? i.e. if someone lives at the top of a long hill and recharges overnight, what happens on the way down? Will the battery be charged over 80%?


  4. 4
    Dave

     

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    Aug 29th, 2007 (10:14 am)

    Lyle – thanks for this post – keep them coming!

    This changes a lot of the previous assumptions about the internal combustion engine (ICE), and the battery:
    – The ICE is not constant RPM
    – The ICE doesn’t really charge the battery much
    – The battery margin is 30% (not 50%)
    – the plug-in charger only goes to 80%

    This clarifies a lot. Mostly good news here.

    My main issue is that the ICE/generator only allows up to an average of 65 mph. There are many states in the U.S. with higher speed limits than this, and regardless of speed limits, the average driving speed is higher. Also, what about Europe? The average driving speed there is closer to 90 mph. Will they get a bigger ICE/generator?


  5. 5
    Nick D

     

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    Aug 29th, 2007 (10:25 am)

    Dave i think you misunderstood the article

    “the peak power of 53 kW will rarely be used”

    “Peak efficiency will be at around 30 kW, which is what the car should require at 65 mph slightly uphill”

    What I understand from this is that 65MPH slightly uphill would use 30kW of the 53kW capacity, this is for peak efficiency, you can go faster (with ‘rough math’ the generator would not sustain a charge if you were going faster than 115 mph) but the “Peak efficeincy,” probabably the claimed 50MPG is at that range.


  6. 6
    Estero

     

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    Aug 29th, 2007 (10:33 am)

    We had previously heard the A123 Systems lithium-ion battery would require A/C to control battery temperatures. Now we’re hearing 1) “If one tried to recharge it by maxing engine output, the cells’ temperature would get too high” and 2) the highest regard level will be 80% even when it is plugged in.

    Hmmm…not sure what to make of this.


  7. 7
    Dan

     

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    Aug 29th, 2007 (10:36 am)

    That really helped. Thanks!


  8. 8
    Matt986

     

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    Aug 29th, 2007 (10:59 am)

    Lyle, great information about the behavior of the Volt!

    From what it sounds like, GM is saying that the genset will kick in when the battery is at 30%, and will only provide power to the motor. Thus the generator would be throttled. And it will also not charge the battery while driving.

    That information is a little disappointing, but I do understand that when you throw a lot of power at a battery to charge it quickly, you get heat, and heat is bad.

    I would think that with the output of the generator being throttled based on demand, it could then present a smaller amount of energy to the battery to charge it without increasing heat too much.

    An alternate idea I thought of would be to use a couple kW from the generator to run the AC system, and route the blower through a heat exchanger with the liquid cooling from the battery to control temperature.

    I think it has to come down to efficiency. We want to get the best amount of travel out of the gasoline we have to burn. So I’m hoping that the genset will charge the battery while it’s running.

    We really have to wait and see how the development goes. GM hasn’t yet determined which battery and generator management scheme will be best.


  9. 9
    Estero

     

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    Aug 29th, 2007 (11:02 am)

    I am really “charged up” (sorry for the pun) about the Volt and look forward to the day when I can actually purchase one. It can’t come too soon. Yet, it is obvious that many engineering challenges lie ahead before Volt 1.0 becomes a reality.

    Controlling the battery temperature appears to be one of the biggest engineering challenges.


  10. 10
    Tim

     

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    Aug 29th, 2007 (11:43 am)

    I am just thrilled that there are so many posters here that not only understand, but have suggestions. Thank you Lyle and all of you for being so involved.


  11. 11
    StevenT

     

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    Aug 29th, 2007 (12:01 pm)

    Just a little money saving quip. I saw in the news where they are trying to get a $7,500 tax break for electric vehicles. I drive approx 12,000 miles a year and except for an occasional trip would use hardly any gas. My calculated savings for what I pay for electricity would be approx. $2,000 a year with gas @3.00 dollars a gallon. My present car gets 15mpg. Given a 5 year loan that amount to a $10,000 savings. So if I pay $30,000 for the Volt and get a $7,500 tax break or even $4,000 that’s now given, plus $10,000 in fuel savings that puts my cost for the Volt @ approx 13-15,000 dollars. Not a bad price for a Volt!


  12. 12
    RE-EV

     

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    Aug 29th, 2007 (1:17 pm)

    I think the initial 60k unit production projection probably has something to do with the tax credit eligibility.

    I’m forcasting a $5,000 fuel savings (over five years) plus a $5,000 tax credit.


  13. 13
    omegaman66

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    Aug 29th, 2007 (1:27 pm)

    StevenT… one problem with your calculations. They haven’t factored in the price of the battery. Pricing on that hasn’t been made public yet to my knowledge. I would imagine you will spend more on the battery per month than you would have on gas.

    This is just speculation but I think it is a pretty safe bet. Here is why. If the price of the battery was going to be small. Say 7,500 dollars are so I don’t think they would consider leasing it to you.

    Also the price of the battery for the Tesla Roadster cost something like 75,000 dollars!!!

    How much cheaper could the volts batteries be???

    ******************
    My thoughts on the battery charging and discharging are a thumbs up. This is much better than what we had previously thought. People were complaining about the battery being charged by the generator. Now we know it wont be designed too do that.

    Any regenerated energy from braking would obviously push the battery charge up… which I would then think allow the generator to run slower and let the charge drop to 30 again. Perfect. Get home and then charge. Thumbs up to GM on that!


  14. 14
    StevenT

     

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    Aug 29th, 2007 (1:36 pm)

    I agree with the battery charging and discharging as well. I think GM is doing it right so people will have a long lasting battery they can depend on for years of service. GO GM. Keep up the good work Kyle!


  15. 15
    voltman

     

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    Aug 29th, 2007 (2:03 pm)

    “Peak efficiency will be at around 30 kW, which is what the car should require at 65 mph slightly uphill”

    This is much different than most cars. The MPG quote for Hyway mileage is at 55. In my car at least, I lose about 1 mpg per 5 miles per hr.

    “So I’m hoping that the genset will charge the battery while it’s running.”

    Why would you want to charge the battery while you are moving? The more you charge the battery with the ICE, the less you can use home power and home power is much less expensive.

    I would think the most efficient way is to use the ICE as little as possible. Also keep in mind they are trying to minimize the number of charge cycles on the battery, even if they are from 30% to 50% or something. The less you charge it, the more it retains capacity.


  16. 16
    voltman

     

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    Aug 29th, 2007 (2:09 pm)

    I have another question.

    If they can run a car at 65mph on a 53kwh generator (at 50mpg) without stopping, then why don’t they build that NOW.
    Hell I would buy that in a heartbeat with no batteries (aside from the small one to start the car and do regen braking like a hybrid).


  17. 17
    Brian

     

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    Aug 29th, 2007 (3:42 pm)

    [quote comment="5495"]I have another question.

    If they can run a car at 65mph on a 53kwh generator (at 50mpg) without stopping, then why don’t they build that NOW.
    Hell I would buy that in a heartbeat with no batteries (aside from the small one to start the car and do regen braking like a hybrid).[/quote]

    this has been raised many times before. the fact is that it takes a lot of time to engineer a new car with a new powertain system. GM announced this car shortly after they conceptualized it. you can’t expect them to just start producing it right away. most cars take about 3 years to start production, so 2010 would right on par with that even without the new powertain and the batteries.

    would you really want to buy something that was slapped together in a few months without extensive engineering and testing? i wouldn’t.


  18. 18
    Dave

     

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    Aug 29th, 2007 (3:56 pm)

    Nick D – Yes, I misunderstood. Thanks for clearing this up.

    omegaman66 – I’ve heard the battery pack for the Roadster currently costs Tesla $22K, but this is a much larger battery that goes over 200 miles. Also, Tesla’s current pricing reflects much lower volume than the Volt.

    voltman – Even if you never plug in, the Series Hybrid design requires a fairly significant battery. This is becasue the instanious peak power (around 170 horsepower) comes from the electric motor and batteries. The gas engine and generator only provide average horsepower, which is around 1/2 of peak.


  19. 19
    omegaman66

     

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    Aug 29th, 2007 (3:56 pm)

    I am with you voltman on the concept. As soon as the serial hybrid catches on and ALL cars are being produced as serial hybrids (or 100% electric) then I would thing that that option will be available. Cars and will increasingly be sold seperate from the batteries.

    Just like you can by after market parts you will be able to replace your volt battery with an after market (suped up or down) battery to suit your pocket book.

    Just like you pick your options of AC, standard vs automatic, leather etc now, in the future the battery will be on that list.

    I can see it now.

    customer: “I want the red one with stereo, leather hold the battery.”

    dealer: “Were running a special right now… I can supersize the battery for you right now for the price of a medium battery.”


  20. 20
    kent beuchert

     

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    Aug 29th, 2007 (4:49 pm)

    Excellent info once again, Lyle. The only blip was one I often make – expressing power requirement as kwh rather than as kw. This also explains why it won’t be a problem to park in the garage with an “empty battery” so that you can put the max amount of cheap grid electricity into the battery for the next outing. Now no need for a “kill ICE” switch and estimating when to trigger it. Neat.


  21. 21
    Estero

     

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    Aug 29th, 2007 (5:21 pm)

    omegaman66 said:
    …Cars and will increasingly be sold seperate from the batteries…

    Just like you pick your options of AC, standard vs automatic, leather etc now, in the future the battery will be on that list…

    I really hope you are wrong on this!


  22. 22
    Estero

     

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    Aug 29th, 2007 (5:46 pm)

    All the information thusfar seems to suggest the power management software will need to be different with each type of battery pack.

    One possible way to address this problem is to incorporate plug-and-play into the battery pack, similar to USB components on computers.


  23. 23
    Mike G.

     

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    Aug 29th, 2007 (6:35 pm)

    Estero says: I really hope you are wrong on this!

    How come! In the future the car, the engine, the battery could all be viewed as separate entities. No need to replace all 3 when 2 of the 3 are in good working condition.

    Get in a wreck that ruins the body but leaves the engine and battery intact. Just buy the body of a car that is compatible with the engine and battery and you are good to go.

    If your comute to work is only 10 miles and you have another vehicle for vacations and pulling the boat then why by the vehicle with the 50 mile range when the one with the 25 range will do!

    Or if you can’t afford the battery at all, buy the car without the battery and after you pay the car off then purchase a battery.

    It doesn’t change anything, just more options!


  24. 24
    Matt986

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    Aug 29th, 2007 (7:00 pm)

    [quote comment="5494"]
    “So I’m hoping that the genset will charge the battery while it’s running.”
    [/quote]

    I understand the idea of getting 100% of your power to charge the battery when plugging in at home saves you money… but what if you’re not going home?

    Like someone else already mentioned, the generator at it’s peak output can’t handle the peak power demand of the motor, so there has to be a battery to act as a ballast. So, the generator has to be able to feed power back to the battery to make up for what it has to use when accelerating.

    I’d prefer it to run like a hybrid – charge the battery however slowly while driving.

    If the car needed less than the ‘peak efficient’ output of the generator (30kW), then the generator should still be run at it’s peak, with whatever surplus there is directed to charging the battery and possibly using the AC system to cool the pack as needed. Then you get the most out of the gas that you burn when you burn it.


  25. 25
    MarioM

     

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    Aug 29th, 2007 (7:25 pm)

    When I read the article, I understood that the engine works to keep the battery at a charge of 30%. Therefore, if the charge does drop below 30%, the engine would charge the battery.

    If I am wrong on this, it would mean that a 53 kW engine could power this car without a battery. That seems highly unlikely to me.


  26. 26
    Drake

     

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    Aug 29th, 2007 (11:11 pm)

    Lyle, thanks for the info man- keep up the good work!

    Matt986 – you really don’t want the generator to charge the battery completely because then when you get home at night, after your commute, there will be no reason to plug the car in.

    StevenT – Bush met with the “Big 3″ auto makers a year or so ago. I believe that during that meeting he probably expressed to them the need for us to move away from foreign oil and maybe even “spilled the beans” that if they created a PHEV/EV then the government would provide some massive tax breaks. In my opinion, giving a $10,000 tax break for each Volt produced would be one of the best investments this nation has ever made. Such a tax break would do two MAJOR things:

    1) Push battery and PHEV technology to the 2.0 mark to where it is so attractive, it would not make any sense to continue producing/buying ICE-only based passenger vehicles.

    2) Bail out GM, etc. from their massive employee retirement responsibilities due to the greater volume of sales/profits that the Volt + tax credits would allow.

    It would Kill two birds with one stone (well maybe it would be a boulder :) . Either way, it would be an epic investment on both scale, returns, and long-term payback. Heck, if we no longer had to worry about oil, we could probably retire one of our carrier groups. How much would that save us every year? Every decade? Talk about some massive returns.

    Brian – don’t worry man, after the Volt is finished, GM will be a different company. It will be black and white to what it is today. I say this because after the Volt is on the road, their knowledge base on designing, building and marketing such vehicles will be vastly greater than it is today. Many of the basic engineering challenges will be overcome with the design of the Volt, and this will allow GM to easily port this technology to other vehicles in its catalogue. The Volt is only the beginning.

    Considering the need to cool the battery, I don’t see this as any different from having to have a massive water-cooling system on ICE-based vehciles today. So instead of having a radiator and coolant system that cools the ICE, it will be cooling the battery and small generator. No biggy in my book. We have to throw away our preconceived notions of what car engines are supposed to look like.

    The Volt is to the Taurus as the Model-T was to the Horse & buggy.


  27. 27
    Mark Bartosik

     

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    Aug 29th, 2007 (11:21 pm)

    This is how I was hoping it would work. It maximizes the amount of home (in my case solar) electricity can be put into the batteries. Best for pocket, environment, and reducing oil imports.

    The last thing that I wanted was to arrive home with a fully charged battery. As someone said that would have lead to people fitting ICE kill switches.

    This also avoids continually cycling the battery on a long journey, which is bad for the battery, and for the ICE (thermal stress).

    Most people will recharge about once per day. So the wear on the battery will be typically correlated to age of vehicle.

    Smart – keep it up Lyle & GM.


  28. 28
    Matt986

     

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    Aug 29th, 2007 (11:56 pm)

    [quote comment="5526"]Lyle, thanks for the info man- keep up the good work!

    Matt986 – you really don’t want the generator to charge the battery completely because then when you get home at night, after your commute, there will be no reason to plug the car in.[/quote]

    Don’t get me wrong, I’m all for getting the most cheap energy from plugging in.

    However, on longer trips, like road trips (I drive from Austin to Phoenix usually about once a year), running the generator at it’s most efficient output, and directing any surplus energy into the battery would be a good idea. Since for that 1000 miles, I won’t be stopping to plug in, I want to get the most out of the gas I burn.

    Say I start driving that way, and hit 40 miles. The generator kicks in and falls to it’s most efficient output – 30kW. But at the speed I’m traveling, the motor is only pulling 20kW. Use that 10kW to charge the battery, and if needed run an auxiliary cooling system (such as running the AC system and venting it’s output through a heat exchanger). After a while, the battery is fully charged and cool, ready to give me another 40 miles.

    For commuting, I live 2.1 miles from work, and have everything I need within a 5 mile radius of where I live. I won’t have to burn gas with my average day to day driving.


  29. 29
    Don

     

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    Aug 30th, 2007 (12:29 am)

    As to cost… Tesla is using off the shelf Li batteries and packaging them in special ways. GM is (presumably) going with A123 which is producing batteries designed for this particular application in a mass production fashion with a Chinese partner (CBAK). Their battery pack will still be expensive but given those production considerations, and that its battery pack (16kWh)is substantially smaller than Tesla’s (53kWh) or either of Phoenix’s AltairNano packs (available in 35 and 90 kWh flavors), it had better cost lots less. Without the battery cost the car also had better be damn cheap. That “under 30K” should cover the whole enchilada with a comfort, performance, and fit comparable to a well appointed Camry or it will be a tough sell to the mass of the American public.


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    Mike G.

     

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    Aug 30th, 2007 (1:21 am)

    We will see (on the cost) I am itching to find out. All that stated above on the battery is good news too me. Too me it is a no brainer that the car excluding the battery should end up being a very cheap car. Way way under 30K.

    As with all things the first is never going to be done the best way at the least cost. Price will come down with competition eventually. GM will have to shrink margins over time. Simple supply and demand AND free market capitalism at work.


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    N Dell

     

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    Aug 30th, 2007 (7:00 am)

    Matt986 – I think that what GM is going for with this car is one that will last longer and is more reliable, so sure you do have your 1000 mile trip once per year, but you will still get 40-50 miles per gallon which im sure is better than you get now.

    Gasoline will have a place in our country for many years to come, I dont see it going away completely in my lifetime, however the way it is used will greatly change.

    That is what makes this car so versatile and amazing, you get your ev in town and this is your gas sipper as well eliminating the need for 2 cars. I forsee garages with 1-2 BEV’s and a volt someday in the future.

    Anyway i agree with maximizing the batery usage by funneling excess energy produced into the battery, but it appears as if this would have ill effects on the life of the battery, something the consumer, and especially GM does not want, especially if they have a 10/100,000 warranty on this vehicle.


  32. 32
    Estero

     

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    Aug 30th, 2007 (8:54 am)

    Does anyone have an explanation for having a battery pack with a theoretical capacity of 16.0 kWh but having NO capability to charge it above 12.8 kWh (80%)?


  33. 33
    OptimisticMF

     

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    Aug 30th, 2007 (9:31 am)

    Estero,

    I think it has to do with longevity. These battery packs have a longer usable life if they are charged within a range (30% to 80%), rather than completely drained and then fully recharged.


  34. 34
    Matt986

     

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    Aug 30th, 2007 (9:58 am)

    [quote comment="5558"]Does anyone have an explanation for having a battery pack with a theoretical capacity of 16.0 kWh but having NO capability to charge it above 12.8 kWh (80%)?[/quote]

    Hybrids already in production do not use 100% of the battery’s capacity. This is to extend the life of the batteries. They last a lot longer if you only discharge them a bit and then do not fully charge them.

    It’s all about getting a lifetime of use out of the battery, rather than having to replace it after a few years… at a hefty price.


  35. 35
    Nick D

     

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    Aug 30th, 2007 (10:30 am)

    I am fairly knowledgeable about battery technology, and understand that this will increase battery life, but i am wondering if people take their car in to the dealership after 6-7 years with a reduced battery range if the dealership will just reprogram and open up the range a bit from 25 to 85 or so to compensate for deteriorated battery life? Any ideas about this?


  36. 36
    Estero

     

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    Aug 30th, 2007 (1:35 pm)

    My thanks to OptimisticMF, Matt986 and Nick D.


  37. 37
    Drake

     

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    Aug 30th, 2007 (10:13 pm)

    Matt986 – I see what you mean. Maybe there should be some sort of a “extended trip” button or something for such times when you know you will be traveling great distances, and would like the best possible fuel economy that the vehicle can muster.

    From a programming standpoint, I don’t think such a feature would be hard to implement. Just have the generator run constantly at it’s most efficent speed until the battery is fully charged and then keep the battery charged with additional runs of the generator.


  38. 38
    law

     

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    Aug 31st, 2007 (7:56 pm)

    This is good news. This means the generator won’t charge up your battery on gas before you get home from work, so you will save on gas.

    This is how the EV/PHEV should operate.


  39. 39
    Pete

     

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    Sep 1st, 2007 (8:52 am)

    Nick, opening up the range of older battery packs by reprogramming would be one approach and the second most economical that I can think of. You could also add a new (or used) module in parallel with the existing battery modules. This would straight-forward if the Volt could be purchased with various battery capacities to support your particular all electric range.

    The most economical means to accommodate old batteries would be have your employer provide plug-in facilities at work – solar powered, of course. One could also stick thin film solar cells on the roof of your Volt, but they are somewhat impractical – expensive, would only give you about one kWh daily when it’s reasonably sunny and you need to have outdoor parking – however, they should last 25 years. .


  40. 40
    Peter

     

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    Sep 1st, 2007 (9:37 pm)

    What is meant by “slightly uphill”? A 1% grade?


  41. 41
    Van

     

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    Sep 2nd, 2007 (10:49 am)

    As I pointed out before, this article also demonstrates the Volt will not be able to travel 40 miles in electric only mode.

    Just run the numbers. How much battery capacity is available? 8 KWH. If you go 65 MPH, you use it up in about 16 miles.

    If you go 60 miles in one hour and use 30 KW average for the hour, you use 30KWH. If you divide, you see you get 2 Miles per KWH. So if you have only eight, you can go only 16 miles on the highway in all electric mode.

    But could you drive more slowly and squeeze out 40 miles? Nope. Lets use the rule of thumb of 1 MPG per 5 MPH. So if you slowed from 60 MPH to 30 MPH your mileage would improve about 6 MPH. Say you 24 MPH at 60 so your mileage improves 25%. Thus you could raise your AER from 16 miles at 60 MPH to about 20 Miles (25% improvement) at 30 MPH.


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    Sep 3rd, 2007 (11:03 am)


    As I pointed out before, this article also demonstrates the Volt will not be able to travel 40 miles in electric only mode.

    That’s what I was worried about. If that’s the case, then I’ll pass on the Volt. Many would like this car to operate in pure EV mode for their daily commute and your 16-20 mile range calculations are disappionting to say the least.


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    Sep 4th, 2007 (9:15 pm)

    As an EE with 30 years of programming experience an onboard power management PC is the obvious choice. You could enter the approx. distance you were going before an AC charge. Most people know where they are going when they get in the car. With GPS and other services (traffic avoidance alternate route) the PC could figure out base on your driving habits (mph in a posted area and altitude cahnges from GPS) how to use the battery capacity for MAX on the grid and least ICE.


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    Sep 4th, 2007 (9:44 pm)

    #41,42

    I am confused as well by these numbers. According the the DOE’s AVTA, the converted Priuses are getting 0.2 kWh/mile.

    http://avt.inl.gov/phev.shtml


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    Sep 7th, 2007 (2:20 am)

    Tesla Roadster averages about 0.24 Kwh per mile, EV1 about 0.2 Kwh per mile, RAV4EV about 0.3 Kwh per mile. The Zap Xebra about 0.175 Kwh per mile but is limited to 40 mph max.

    Yes, I suspect Van is partially right – as currently proposed, the Volt would only have a 16 mile EV range at 60 mph. However, for lower speeds, the milage increase isn’t linear, and a 40 mile EV range might be possible at speeds around 35 mph. I sometimes suspect that the figures given out by GM are based more on marketing (what they hope to achieve) than engineering, and the figures may well change before production and sales start.

    I see no reason for the gas engine to fully charge the battery, even on long trips away from power outlets. Doing so would not improve fuel economy, and the car would still operate normally as there would still be plenty of battery power to start the range extender when needed. Besides, I envision a future with convenient recharge outlets in parking lots at roadside diners, rest stops, motels, shopping malls, offices, etc. Even if these outlets charged a bit more for electricity, it would still be a lot cheaper than gasoline.

    If you look at the graph at the top of the page, you will notice that even during “charge sustaining mode”, the State of Charge fluctuates, as there are times when extra power is needed from the battery, and times when extra power is available to partially recharge the battery.

    It is nice to know that the range extender engine normally operates at its most efficient speed and power output, but can rev up to a higher power (though less efficient) speed when needed – useful to prevent the battery from being drained too low under long heavy demand conditions, like a long steep climb up a mountain pass.


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    Niel

     

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    Mar 17th, 2008 (3:35 am)

    I own a 1998 Chevy S10-EV, a GM factory made electric vehicle made at the same time the EV1 was made, and it uses the same motor, controller, and batteries (NiMH) as the EV1.  There are 60 of these vehicles in existance that escaped the crusher at GM, and most of them are on the road today.  Here are the figures I took for energy consumption in my vehicle:

    10 mph  189 wh/mi
    20 mph  193 wh/mi
    30 mph  278 wh/mi
    40 mph  292 wh/mi
    50 mph  292 wh/mi
    60 mph  296 wh/mi
    70 mph  334 wh/mi

    The figures were taken from a GM scan tool which monitors battery voltage and current, while doing my best to drive the vehicle at steady speed on a flat road.  I was not able to do the tests under perfectly controlled conditions.

    This vehicle (an S10) has the aerodynamics of pushing a brick through the air, and it weighs 4100 pounds.  With these figures of a quite un-aerodynamic and heavy vehicle, the volt’s 8 KWH battery would power my S10-EV for 27 miles at 60 miles per hour.  I could easily see that the Volt will be significantly lighter and way more aerodynamic, so a 200 wh/mi figure would be believable for a light aerodynamic vehicle at 60 miles per hour, thus producing a 40 mile range.  I don’t believe the 25 KW power consumption figure for the Volt at 60mph.  My heavy, brick shaped vehicle it uses 18KW at 60 mph. 

    By the way, we absolutely love our S10-EV.  It’s too bad there aren’t more of them.  I’m really looking forward to the Volt’s release.


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    tai viinikka

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    Jun 20th, 2008 (4:52 pm)

    Lyle: Those energy requirements will roughly be about 8 kWh in the city, and 25 kWh on the highway.

    Er, you mean power requirements of 8 kW in the city, 25 kW on the highway? Energy requirements doesn’t make much sense in this context.

    Am I confused?


  48. [...] according to the folks at GM Volt, the Zap Xebra about 175 watt-hours per mile but is limited to 40 mph max. Neighborhood EVs (NEV) have an average [...]


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    Jim West

     

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    Jul 20th, 2008 (11:18 am)

    The high cost of the Volt’s Lithium-Ion battery will kill the Volt.
    Anyone that thinks a nearly $20K battery is practical is living on another planet.


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    Jul 20th, 2008 (12:20 pm)

    Jim,

    How do you know what the Volt’s Lithium-ion battery is going to cost, when the car is released 2 years from now?


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    Jul 20th, 2008 (2:14 pm)

    Anyone that thinks a nearly $20K battery is practical is living on another planet.

    Probably. But just for comparison, what does a new GM V6 engine, transmission, injectors, valves, alternator, and 12 V battery cost?

    I think $4/ga gasoline is totally impractical, but that doesn’t change the price. So what do I do now?


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    Jul 28th, 2008 (9:27 am)

    Just drop the whole battery and ICE…

    Just use some Ultracapasitors… 500 mile range.. 5 minute charge..

    Who needs anything else? Even if you only get 1/2 the range and double the charge time? so 250 miles, 10 minute charge up… Wouldn’t you still buy it?

    Source: http://www.msnbc.msn.com/id/20533045/


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    Aug 1st, 2008 (12:12 am)

    #49 Jim West

    a nearly $20K battery?

    Expected 8kwh volt battery to be about $6k and drop precipitously with expanding mass production. In comparison Tesla roadster battery is 53kwh and has gone from $25k in ’06 to about $22k currently and there have only been about ten production and 20 preproduction Teslas made so far.

    # 52 Brandon

    Ultra caps currently have a lower energy density than commodity lithium batteries and are therefore bigger and heavier than a battery pack with the same charge capacity. The wonderful ones projected on the msnbc article are unfortunately still just projected and currently for sale in automotive applications as vapor ware only editions.


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    Karn K.

     

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    Jun 29th, 2009 (9:57 pm)

    Mike756, I have simple answer for you:-) Do not charge the car if you live on the top of the long hill. This will allow you to regen brake and charge your battery while you go down hill.


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    Roy

     

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    Aug 24th, 2009 (11:23 am)

    press releases indicate 25 kWh / 100 miles energy efficiency in electric mode or 10 kWh / 40 mile range. This would mean that 62.5 % of the battery capacity would be required to achieve the stated 40 mile range. That leads me to believe that plug in charging does take the battery to full capacity making 11.2 kWh available before the gas generator starts (at 30% charge) for a slightly longer than 40 mile range at the 25 kWh / 100 mile efficiency. I have also come across a 50 mpg figure for extended range driving. I don’t know how much the battery pack actually costs except that it is significantly less than $1000 / kWh. When it gets below $200 / kWh more people will be able to afford to buy a Chevy Volt (or similar PHEV). It will be interesting to see the price and sales volume when it hits auto dealer showrooms. An economic recovery and $5 / gal gasoline would help a lot but I’m not sure when we’ll see that.


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    Leann Musselwhite

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    Mar 10th, 2010 (5:40 pm)

    This website looks great and reads even better! You share some great opinions and insight here. Always looking for motivating blogs to keep mine going!


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    Bob Plugh

     

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    Mar 12th, 2010 (10:58 am)

    The one thing about the Volt to think about is this… Consider just WHO is building it. Consider the fact that they have had how many years to develop this technology and haven’t. The only reason they’re doing it now is that their hand is being forced by other companies who ARE coming up with electric vehicles. GM has already bungled very badly, going from the largest auto manufacturer in the world to a scant 2nd place. Even with the problem Toyota has, people still prefer them to GM. Look at how long their hybrids have been around and GM has done virtually nothing. I predict this Volt will be a miserable failure with more problems than you can shake a stick at.