GM Did It Again! Volt discussion thread

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Originally Posted By: JHZR2
Frankly, to cruise any sort of time over 70 MPH I would WANT an IC engine.

Li-ion batteries have great specific energy and power, but I would not want to deplete them too deeply, too fast. It is a matter of the capabilities of the current SOA for Li-ion batteries, NOT GM engineering... OK I take that back - they could have made the pack much larger so the cells operate at a lower rate, and all would be well... And then people would have gripes over that too.

It is all about balance. No matter what anyone says, this car is just a prototype until items outside of GM's control can be solved.


But what does the SOA of the batteries have to do with this.

I see the electric motor as a device that gets power from an electrical bus. The motor doesn't know if the power comes from a battery or from a generator.

There is a controller that determines how much power the motor needs for a given circumstance and chooses how much from each available source, battery and generated power.

The motor doesn't care about the source, and if the batteries are not sufficiently charged, the generator is called up to supply some or all of the power.

If we can modulate how much current goes into the motor, can't we also modulate how much current we draw from the battery and from the generator?
 
If there are operating conditions under which a mechanical connection between the IC engine and the drive wheels is more efficient than a motor/generator connection, then it should have the capability to use a mechanical connection and use it under those conditions.
 
Not for or against GM but the bottom line is that from an engineering and marketing standpoint, they compromised.

If it was found that the car couldn't go above 70 MPH, would it have flopped?

So depending on how you see it, they either chickened out or had to make a hard decision.
 
Man I wish I had some money to spend irresponsibly!

I'd have been willing to bet that I could get an electric motor powered Ford/Kia Festiva or Suzuki/GM Sprint to cruise at 70mph for a fair distance with a bank of lead acid batteries being continously recharged with my Chinese OHV Honda clone generator.

I understand that it can't run like that all day... not on 4500 rated watts. But probably for a fair distance.

I might have to build a small trailer for the generator....but that's beside the point.
lol.gif
 
It sounds like some of the people aren't thinking this through.

If they could do it with the gas engine as a generator at 70 ph and not be connected to the wheels and found it to be (just a number) 60% efficient, and then discovered if they just used the gas engine at 70 mph and found it to be 70% efficient,

how can anyone fault them on that?
 
I think the point of the OP was to how they are marketing the product. I see nothing wrong with the product as is, but calling it something it isn't and insisting it isn't what it is, won't help sell it or the image of GM.

This type of marketing is a good way to kill what may be a fine product.

-Spyder
 
Bravo GM, I could not expect anything less from them.

Next big shocker, Volt doesn't get the advertised 230mpg because a month before launch, the suits discover they cannot bend the laws of physics as they originally hoped so.

This is more entertaining than TV these days, and if this sharade wasn't on taxpayer’s dough, I would be laughing.
 
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Re-read the OP. They are stating, categorically, it is electric only.

I have no problem with them not being able to achieve that and having to modify the design to make it more real world usable. But concealing facts and meeting honest questions with answers that contradict it, is not a good way to win over consumers.

Especially if the consumer spends tens of thousands of dollars under the impression, based on their marketing, that they are getting something other than what they were led to believe they were buying.

Such are the tactics of sleazy used car salesmen, and not an acceptable practice from a major automaker - particularly one already caught in a public perception transition.

-Spyder
 
Originally Posted By: javacontour
Originally Posted By: JHZR2
Frankly, to cruise any sort of time over 70 MPH I would WANT an IC engine.

Li-ion batteries have great specific energy and power, but I would not want to deplete them too deeply, too fast. It is a matter of the capabilities of the current SOA for Li-ion batteries, NOT GM engineering... OK I take that back - they could have made the pack much larger so the cells operate at a lower rate, and all would be well... And then people would have gripes over that too.

It is all about balance. No matter what anyone says, this car is just a prototype until items outside of GM's control can be solved.


But what does the SOA of the batteries have to do with this.

I see the electric motor as a device that gets power from an electrical bus. The motor doesn't know if the power comes from a battery or from a generator.

There is a controller that determines how much power the motor needs for a given circumstance and chooses how much from each available source, battery and generated power.

The motor doesn't care about the source, and if the batteries are not sufficiently charged, the generator is called up to supply some or all of the power.

If we can modulate how much current goes into the motor, can't we also modulate how much current we draw from the battery and from the generator?


You are right, but this is my thought process:

-Batteries must be recharged far slower than they can be discharged. In come cases, that ratio is up to 400 to 1. Bad things happen at either end of the charge/discharge spectrum (which is why the volt batteries are derated 50%). As one might imagine with an energy source that is finite and FAR less dense than liquid fuels, it would make sense to conserve for situations where the battery could be best utilized. Batteries make best sense as a topping power source for peak power and slow recharge in-between. The pack would need to be far more sizeable than what is in a volt or leaf to be able to handle more duty.

-Some of the initial article and posts seem to imply that the thing is a flop if it cannot cruise all day (or at least some range) at 70 MPH. But again, this is where the batteries do not make sense. They will work fine for a sustained low-discharge rate operation, but low discharge rate is relative and once discharged I do not believe that going from 0% SOC to 50% SOC or similar in the amount of time that it takes to fill an IC's tank would be prudent in the name of battery safety. Meanwhile, you just used a battery (90% round trip efficiency plus generation efficiency of 40% = 36% total) in a situation where the IC engine with smoothing from the energy store would allow optimized efficiency gains without as hard operation of the battery, reduction of its cycle life, or having to deal with safety issues associated with using it thoroughly. I call it smarter, more prudent engineering to move to IC with battery assist over some reasonably low speed. Let the battery ops be best suited for what they are - low speed ops.
 
Originally Posted By: JOD


Bit of an understatement, don't you think? Seems like a completely different car to me??


This seems like a pretty big mis-step to me, particularly given that it was hyped so much as being superior to other hybrids since it didn't have a combustion engine...


From these statements it's easy to conclude you NEVER have had a grasp of what the Volt was and how it's design works.

Can you please show me a link to the Volt prototypes that didnt contain an ICE?
 
Isn't one of the main reasons why locomotives use their diesel engines to power a generator is that they need an equal amount of power at each drive wheel of each locomotive?
 
This is what GM is hailing it as:

"The Chevrolet Volt is not a hybrid. It is a one-of-a-kind, all-electrically driven vehicle designed and engineered to operate in all climates."

Now tell me, precisely, how you do reconcile a 1.4L internal combustion gasoline powered engine with a " one-of-a-kind, all-electrically driven vehicle."

Again there is no problem from my perspective with it being what it is. I do see a problem for GM in trying to reconcile the two statements when payment is due.

That is not my problem. That is GM's problem. And there is nothing "bashing" involved in pointing out a blatant, black and white contradiction for what it is.

-Spyder
 
Originally Posted By: JHZR2
Let the battery ops be best suited for what they are - low speed ops.


Don't forget about Peukert's Law, which is that as the discharge rate of a battery increases, the capacity of that battery decreases.

In other words, a battery rated at 10AH is only rated as such at the C/10 rate (that is, one amp for 10 hours). If you tried to draw C/1 (10 amps), you might only get 45 minutes, not an hour.
 
I agree, the final version will better than ICE working as a generator only, but it is bait and switch. There is speculation that it was done to protect GM patents.
http://www.dailytech.com/GMs+Chevy+Volt+...rticle19852.htm

How do you reconcile this latest announcement with this:
http://www.popularmechanics.com/cars/alternative-fuel/electric/4215492

http://www.motorauthority.com/blog/1028143_gms-plug-in-volt-concept

Ford chose to license Toyota hybrid technology, GM developed their own, from the sounds of it. Good for them.

I do not begrudge GM making a better, more efficient Volt, but be honest about what it is and what it is not.
 
Agreed, label it as you see fit. But like I said previously, it amounts to nothing imo. Interesting what Nitz revealed about the switch.

The proof is in the pudding and in the end it's more efficient as built, and delivers on it's promised performance as designed. Sure they give fodder for those looking to complain about something. But the truth is, it's a better design this way.


As to the design as it exists now...I'm trying to figure out if the ICE charges the batteries as it also powers the car after battery power is depleted. In other words, could you drive 40 miles, then switch over to the ICE for a period of time, then switch back to battery power for another 40 and so on and so on.
 
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