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Discussion Starter #1
First of all, hello everybody!
I am a mechanical engineer and I have lots of interest in EVs and hybrid technology.

So, after reading and watching quite a lot on the Chevy Volt's design and operation modes, I couldn't help asking myself has this design, with all its innovation, missed the whole purpose?
Of course, that depends what was GM's purpose in the first place. Building a sophisticated novel machine, or offering the people a real alternative to gasoline cars?

I think that two major wrong decisions were made initially in the design process: Battery Chemistry and the VOLTEC transmission.

As I far as I studied this subject, going with Lithium Iron Phosphate (LFP or LiFePO4 ) chemistry would have yield a cheaper, more compact and longer lasting design, while still supplying the same performance of range and acceleration. I saw a video where one of the Volt's development team said he is satisfied with their choice of Lithium-Manganese-Spinel. I also read that Chevrolet are still interested in LiFePO4 chemistry, but didn't choose it because A123 couldn't assure delivering LiFePO4 cells at the quality needed for a manufacturer the magnitude of GM.
I am speculating a little here, but I think goint with LiFePO4 is much better choice. This chemistry has much longer life cycles, it can be discharged almost 100% and still live long. It is also much less sensitive to heat aging, so it could be just fine with a simpler cooling system. All in all, the LiFePO4 could be only 12KWh, with a more compact cooling system, and this would have taken much less space from the car interior. So a fifth seat could be availible that way. This would have reduced the battery cost. LiFePO4 is a little bit heavier per KWh, but it does not occupy more volume. It could still deliver the same 10 KWh the Chevy uses out of it's 12 KWh without degredation. The same for the 110 KW peak power.
LiFePO4 would be:
Cheaper to buy (smaller capacity), cheaper to build (simple cooling) and allow for a fifth seat.

I also doubt the cost effectiveness of the VOLTEC drivetrain, compared to a simple series hybrid design. losing 10% to 15% efficiency at speeds higher than 70 mph sounds alarming, but it is not that significant. GM themselves said the VOLTEC contributes a mile or two to the CD range of the car, hence less than 5%. (The difference is probably because most of the time the car's speed is lower than 70.)
Does it worth the extra cost, design time, complexity, reliability and space? Wouldn't buyers prefer a reduction of a few thousands dollars of the car's price even if the engine will kick in a mile and a half earlier? I guess lower efficiency means that the gasoline consumption in those speeds will have to rise as well, but that will raise the annual fuel cost from smallish $600 to $630. I would prefer paying extra 30$ a year and get a cheaper car to buy and repair.
GM could also simply advise buyers not to exceed 70 mph from an aerodynamics viewpoint, this I think would be understandable.
And if you really want a few percent efficiency gain, you could give the car a slightly lower final reduction ratio so the motor will not get to such high rpm. You will might need another half a second to accelerate from 0 to 30 mph, but acceleration from 30 mph and on will be identical.

Last thing, I heard unofficially that the Renault Fluence EV will have a brushed motor. This can reduce cost even further, while still guarantee 180,000 miles maintenance free.
 

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I thought A123 would be considered an alternative supplier earlier-on in the GM design process but then got pulled off the table.

Do you think A123 is going to supply enough to Fisker for the new models? Sounds like at least A123 has a buyer there and may be able to extend that further to other suppliers.

I would not use a brushed motor in any vehicle these days - with brushless technology offering more efficiency, what kind of data do you have that Renault is going to benefit with the brushed? Now, my experienced with brushed/brushless is simply in the RC car racing hobby - but brushed motors there are just not smart. Brushes wear out and need special tuning and care. Brushless is just far more maintenance-free.

Did you see the press items that the Kia Optima Hybrid will be using LiPO cells? That could spell trouble as LiPO cells could be a fire-hazard due to over-charging or damage in a crash. LiFEPO4 will vent without flame.
 

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Hi Tom, here is my take on the two issues you've raised. With respect to the batteries, GM went with the best available and most cost effective solution. LG Chem has inked so many more deals with other automakers that I don't think the choice was all that close. Yes the A123 batteries have some better characteristics, but if you can't package them and there are safety issues then the superior features aren't really brought to bear.

With respect to the EVT, it's a great design and so vastly superior to say, what BYD has shown as a serial hybrid that it's not even funny. (You can read about a BYD test drive in the NY Times). It's also not nearly as complex as you're making it out to be. In fact in many ways it's simpler than the TRW split power gearing used by Toyota and Ford, and that design has proved more reliable than a standard transmission.

As for what the Volt was designed to do, it was designed as a Prius killer. It accomplishes that task without question.
 

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Obviously having education and "interest" is one thing. But having actual EV knowledge and experience quite another.
If you examine the developmenal history of the Volt, you will find that GM conducted a series of engineering competitions to determine the ultimate battery technology for the Volt. A123 participated and were not selected for a myriad of stated reasons, not the least of which was a serious lack of long-term durability and accelerated "end-of-life" through daily charging cycles.The successful candidate after these accelerated tests, which were conducted over 24 months was the LG cell chemistry currently in use in the Volt. it is quite simple the best EV battery technology that exsisted at the time, BAR NONE.
You can look at research papers and battery data sheets all you want, but in the end "real world" results are all that really matters.

Same thing goes for the transaxle. You're about 4 years late to the conversation. Over the past 4 years we've had all sorts of "experts" here on gm-volt.com expounding on the virtures of this or that EV drive technology. The reality is the technology that the Volt is using is the most sophisticated and efficient series power transmission hardware in existance, BAR NONE.
Until someone comes out with something that can compete with it, anything else is (like you said) mere speculation.
Talk is cheap, but real execution comes with challenges and hurdles that conveniently miss the napkin.

WopOnTour
 

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Obviously having education and "interest" is one thing. But having actual EV knowledge and experience quite another.
If you examine the developmenal history of the Volt, you will find that GM conducted a series of engineering competitions to determine the ultimate battery technology for the Volt. A123 participated and were not selected for a myriad of stated reasons, not the least of which was a serious lack of long-term durability and accelerated "end-of-life" through daily charging cycles.The successful candidate after these accelerated tests, which were conducted over 24 months was the LG cell chemistry currently in use in the Volt. it is quite simple the best EV battery technology that exsisted at the time, BAR NONE.
You can look at research papers and battery data sheets all you want, but in the end "real world" results are all that really matters.

Same thing goes for the transaxle. You're about 4 years late to the conversation. Over the past 4 years we've has all sorts of "experts" here on gm-volt.com expounding on the virtures of this or that EV drive technology. The reality is the technology that the Volt is using is the most sophisticated and efficient series power transmission hardware in existance, BAR NONE.
Until someone comes out with something that can compete with it, anything else is (like you said) mere speculation.
Talk is cheap, but real execution comes with challenges and hurdles that conveniently miss the napkin.

WopOnTour

*** you are one crazy smart dude! I hate to ask your background for fear I/we will feel even smaller.
You're even well spoken to boot!
Thanks for the exceptional answers on every post I read.
Aloha!
Cody
 

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Obviously having education and "interest" is one thing. But having actual EV knowledge and experience quite another.
If you examine the developmenal history of the Volt, you will find that GM conducted a series of engineering competitions to determine the ultimate battery technology for the Volt. A123 participated and were not selected for a myriad of stated reasons, not the least of which was a serious lack of long-term durability and accelerated "end-of-life" through daily charging cycles.The successful candidate after these accelerated tests, which were conducted over 24 months was the LG cell chemistry currently in use in the Volt. it is quite simple the best EV battery technology that exsisted at the time, BAR NONE.
You can look at research papers and battery data sheets all you want, but in the end "real world" results are all that really matters.

Same thing goes for the transaxle. You're about 4 years late to the conversation. Over the past 4 years we've has all sorts of "experts" here on gm-volt.com expounding on the virtures of this or that EV drive technology. The reality is the technology that the Volt is using is the most sophisticated and efficient series power transmission hardware in existance, BAR NONE.
Until someone comes out with something that can compete with it, anything else is (like you said) mere speculation.
Talk is cheap, but real execution comes with challenges and hurdles that conveniently miss the napkin.

WopOnTour
Thanks for weighing in with real world data! Seems like folks are just lining up to take their own shot at the Volt and how they know better one way or another. These are generally pathetic individuals, and should probably be in therapy.
 

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Discussion Starter #8
Thank you all for your kind replies.
Apparently you have much deeper knowledge than me and that is great.
I guess I am late by 4 years or so...
Anyway I have no complaints to GM, and I do think the design is a great achievement and very thoughtful. I just read on the internet rumours about building a "baby volt" with shortened range, because the price of the Volt is just so high.
Than I read more about the design and wrote my reflections about this.
I think if LiFePO4 batteries are feasible for 2012, they do allow many advantages as I wrote earlier.
I also still think that potential customers would give away a few percent in efficiency, if the car price will be reduced by "X" dollars.

In regard of the Fluence ZE, I saw that in a youtube video taken at Better Place visitors center in Israel. I don't know who is the man who says it but looks like he knows what he is talking about. He claims the Renault Laguna EV mules (used by better place for demonstration to the public) had brushless motors, but the Fluence ZE will use "regular" motor. When asked by a visitor "does the motor, because it does use "coals", will need maintenance or something? ", he responds: "there is no maintenance, the manufacturer himself said 300,000 Km without". He also said the motor is 70KW continuous and 85KW peak.
You could have judged by yourself if the video was not in hebrew.
Clearly you have much more knowledge than me, so I would like to ask your opinion regarding the price saving and the efficiency loss of such a motor.
 

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tomerb,

Yes. GM has built a car that can only sell with massive government aid, which is really a transfer payment to the ROK to encourage their leadership in battery technology. And they did it just because Bob Lutz had massive Prius envy.

Whether or not A123's chemistry should have been selected, I can't say. However, it certainly stings that battery development, called by many a "strategic" technology, is being subsidized in the ROK by my tax dollars.

WOT,

Face facts, they way they built it, it IS a Prius, just with a bigger battery that helps the ROK to enjoy a commanding lead in that tech, greater curb weight, reduced passenger capacity, software that discourages blending of electric and ICE power until it's unavoidable, disappointing range-extended fuel economy and a far larger price tag. Whoop-de-do.

Another poster recently pointed out that the majority of Leaf excursions were on the order of 7 miles or less. Some of us already knew that Toyota's plan to extend the Prius with a larger but still reasonably priced battery, a modest 12 miles of range and reasonable price tag was likely to be the smart way to go. Now, the rest of you have no excuse for any lingering ignorance on that score.
 

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"WOT,

Face facts, they way they built it, it IS a Prius, just with a bigger battery that helps the ROK to enjoy a commanding lead in that tech, greater curb weight, reduced passenger capacity, software that discourages blending of electric and ICE power until it's unavoidable, disappointing range-extended fuel economy and a far larger price tag. Whoop-de-do."

Yea I'm not sure you get it, I only get from your statement that you are indeed a GM hater. You attempt to marginalize every statement, yet with no real facts to back your statements up. You just give unfair comparisons that in no way express what is really going on in the market.
You're upset that our tax dollars are going to support EV's, I get that! But how many BILLIONS AND BILLIONS of tax incentives go to the oil companies just in the last year. Don't you think it's more important to talk about Billions rather than a 75 million dollars this year going to EV buyers? GM will build about 10,000 cars this year. They could see a tax credit of $7,500 for a total given out in the way of credits of 75 mill. I don't know about you, but I would rather ordinary citizen's get the billions of dollars in credits rather than a corporation that rapes us every year. At least our economy would see positive results from this influx of cash.
Re: Prius being similar to the Volt. Yea, not quite. The hard truth here is that the Prius is so invested in technology developed 15 years ago that it still carries an engine from that era, batteries from that era and EV blending more similar to their first Prius than the Volt. The Prius is a good car, it delivers great real world mileage, but it can not touch the Volt. If that were true, why would Toyota be working so hard right now to copy the Volt to make it a Lithium Plug-in?
Another thing you fail to realize, there is room for many EV's and PHEV's in the market. We need Fusion's, Focus EV's, Prius', Leaves, Volt's and iMEV's in the market. They will all serve their duty and they are all good machines.
The Volt just so happens to be the most developed of them all currently.
 

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"no facts to back it up..." What facts are lacking?

Battery? Both
Planetary gears? Both
Two M/Gs? Both
ICE? Both
Runs on EV alone? Both
Runs on ICE alone? Both
Sells in the millions? Waiiiit... You're right... GM didn't build a Prius.

As for the BILLIONS and BILLIONS in tax incentives to oil companies... Please point to any of my writings that endorse incentives for oil companies.

"why would Toyota be working so hard right now to copy the Volt to make it a Lithium Plug-in? "

Who says they're working hard? They've already done it. They're just making sure that it works rather than having the buyer beta-test it and find out the battery craps out prematurely. If you want to drive one, today, sign up with ZipCar. They have several. A PHEV for Toyota is a no-brainer... scale up the battery, adjust a few software parameters and done.

"The hard truth here is that the Prius is so invested in technology developed 15 years ago that it still carries an engine from that era, batteries from that era and EV blending more similar to their first Prius than the Volt."

The truth is, that engine is more sophisticated than the Volt's. The Toyota engine does its work on regular gas, didja notice? What does that Volt require? Power blending allows for all parts of the car to work in harmony when it's useful to do so and individually when that makes more sense. If it wasn't for the Volt's shameful secret (that it does directly drive the wheels from the ICE), the gas engine would be a useless lump. Carrying around a couple of hundred pounds of iron for no reason does no one any good. Compare vehicle weights and get a clue. Old battery tech? Old battery tech that works and delivers value. Whose hybrids sell in the millions? Whose hybrids sell in the dozens?

"There is room for EVs and PHEVs in the market."

True. But it's a waste of time to build vehicles that won't sell without massive subsidies. Building a boutique automobile that makes no difference is a pointless waste of time, especially for a manufacturer that can not survive on boutique automobile sales. Ford knows. Toyota knows. God knows, Honda tries.
 

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my critisizm is,
for a car that stickers for 40 grand,
they left a lot of performance on the drawing board.

the gas motor redlines at 4800 rpm,
but has 4 valves per cyl,
and variable valve timing.
WTF.

do the people at Chevy know what a turbocharger is?
Or maybe an electric supercharger. 10 hp would be plenty.

IMO, they gave up a lot for these two issues.
one speed drive train ... no gear shifts,
and,
CS and CD, absolutely the same performance.
(you can level down, but you can't level up.)

edit.. let me add, for 40 grand, I expect suspension components
in the class of a Corvette, not a Cobalt.
The Volt has IRS, or not?
What is up front,
Mac struts, or wishbones?
 

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c_harnett (et al)

All you are really doing is demonstrating just how little you really understand the Volt (or the Prius for that matter)
The size and number of electric motors, as well as battery power and energy specifications are quite irrelevant if you don't understand the fundamental differences between input, compound, and output splits in power and how to take advantage of them as required, when required.
The Volt is unique and anyone that really understands the theories of operation, even at Toyota, would tell you so.
If it was just a simple matter of putting in more battery & motor for the Prius to compete with the Volt, Toyota would have done so.
It's just not that simple.

In any case,
I strongly urge you to take your toy ball and go back to the sandbox of the Priuschat board and stay there.
We have ALL your IPs and domain names and know you're just the same old troll.
I'm sure you think you're real smart going all "incognito" but...

WopOnTour
 

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Discussion Starter #17
Regarding the 1.4 Engine, I know it was chosen from GM's inventory to save development cost and time and that makes sense. I still think that the next version of the Volt could be just fine with a more simple engine. If the engine is working in a narrow RPM band controlled by the car's computer, maybe it can do just fine with fixed valve timing and 2 valves per cylinder? I dont know what will be the reduction in production cost, but it might get almost identical MPG with a lower priced car.
I know that in CS mode while during mountain climbing, the output of the gas engine determines your final speed up the hill, so why not use the navigation system in the car to engage mountain mode in advance, so high-revving the gas engine could be avoided?
 

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Regarding the 1.4 Engine, I know it was chosen from GM's inventory to save development cost and time and that makes sense. I still think that the next version of the Volt could be just fine with a more simple engine.
My vote goes to the OPOC engine. Compact and highly efficient, it looks to be ready for primetime pretty soon....

http://www.ecomotors.com/
 

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My feeling is that GM went with LG Chem batteries because LG is a much bigger company and could stand behind the product in the event of a field campaign (i.e. recall), whereas A123 is a small upstart that doesn't have the money to to help pay for warranty issues should they arise. And although A123 is staffing up pretty quickly and has a great battery, they just don't have the same technical depth as LG, which is a multi billion dollar company.

I completely disagree with your assessment of the transmission choice. A single speed design would be a disaster and provided poor acceleration and poor hwy efficiency. Consider that the loss in efficiency would be in addition to the mechanical/electrical losses already experienced in going from the battery to the wheels. Overall losses would probably be in the 30+% range at high speeds. That's a lot of wasted energy and which is lost in the form of heat generated at the motor. Not good for batteries, the motor, or overall vehicle range. I love it when I'm on the hwy and get passed by a Volt. It's certainly not your typical EV!

An induction motor is really the only option. Going to a brushed motor would be a step backward...and there is a lot of maintenance and adjustment needed as others have said.

My only complaint with the Volt is that they didn't use a direct injection engine for the ICE. That would have been good for a least a couple more mpg on the hwy (or more) and eliminated the need for premium fuel. I bet we'll see that corrected in Gen II.
 

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Discussion Starter #20 (Edited)
I dont agree that single speed is a disaster. The Fluence has single speed. Tesla roadster has single speed. Tesla went from two speeds gearbox to a single speed, and thanks to motor and electronics changes, they actually improved both 0-60 time and driving range.
http://en.wikipedia.org/wiki/Tesla_Roadster
maybe the overall losses are 30% like you say, but GM say it is only 10-15% worse than the Voltec drivetrain.
This whole issue is only while in speed in excess of 70 mph. even without the Voltec you should still get the same efficiency while driving at reasonable more economical speed. I think it was Pamela Fletcher who said the Voltec drivetrain extended the EV range by one to two miles. that is not so catastrophic difference IMHO.
In regard to acceleration- you will still keep the same initial acceleration while losing efficiency only at high speeds. or you could change final ratio and keep the high speed efficiency, with a slightly slower 0-30 mph time.

It says here that the Fluence ZE has synchronous motor with rotor coil:
http://www.greencarcongress.com/2010/04/renault-20100415.html
I dont know what it means, but the last comment to the article, by MG, speaks about replaceable brushes.
BTW the fluence is limited to 84 mph only, do you think it might be because of a motor limitation?

What I am basically asking is, do the choices made are cost effective? does the Volt really has to have every technology known to reduce mpg a little bit more? does the Volt's purpose is to be a Prius killer like DonC said here? The Volt is without a doubt more impressive than the prius, it has better styling both inside and outside, more power, and better handling, and it goes in EV mode further even than the future plug-in prius. But is the Volt appealing to drivers who look to save money? are a few more percent of efficiency worth a considerable price gain? I think with the Volt GM have definitely showed their capabilities, so now maybe it is time to take a step back and release a deliberately inferior car which is much more reasonable priced, even if its EV range is 2 miles less.
Otherwise when the tax incentive is over, the Prius might turn out to be the killer...
 
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