IL Corrects Volt Story: Batteries Will NOT Charge When Driving; GM Website Differs

[tripowergto]

Daniel Pund, Senior Editor, is an idiot media puppet. He probably thinks the VOLT concept is a coupe!

[jbartley]

this doesn't match the press release which talked about keeping the batteries between 30% and 80%...uhhhh riiighttt mr. journalist.

[desmo9]

Originally Posted by Perian

Link: http://www.edmunds.com/insideline/do...ticleId=132112

DETROIT — Remember when we wrote that the 2011 Chevrolet Volt would be able to run 40 miles on pure electric power and then fire up an onboard four-cylinder engine to recharge the batteries?

Turns out, that's not at all true.

In contrast to popular (and our) impression, once a driver uses up his 40 or so miles of electric power, the 1.4-liter gas engine generates electricity to power the electric drive motor, but does not recharge the batteries. After the 40 or so miles, the battery becomes 400 pounds of uselessness, at least until the owner can plug the car into the electrical grid for a recharge. This means that regardless of how far one drives the Volt, the driver will only ever get up to 40 miles of electric-only range.

Our confusion and that of much of the media corps might have to do with the fact that the company once wrote this: "When the battery is depleted, a 1-liter, three-cylinder turbocharged engine spins at a constant speed, or revolutions per minute (rpm), to create electricity and replenish the battery."

That was from a press release written for the 2007 Detroit Auto Show, where the Volt concept was unveiled. A release from the day of the production prototype's reveal reads, "a gasoline/E85-powered engine generator seamlessly provides electricity to power the Volt's electric drive unit while simultaneously sustaining the charge of the battery." And by "sustaining" GM says that it means only that no additional power is drained from the batteries. Get it?

Sorry, but no I don't. It may be true that the engine never charges the battery, but therefore the battery is not "sustained" after 40 miles, either.

We know the engine can't get it done alone, or we'd not be hearing about a finite 600 or so mile total range. Meaning, once the 40 miles of battery-only propulsion is done, the engine and the battery are working together. If the engine were sufficient to propel the car and "sustain" a constant battery charge from 40 miles onward, then the car wouldn't have any 600 mile limit -- it'd be like the energizer bunny, going and going so long as fuel's in the tank. Therefore, I think this guy's missing the point. The battery must indeed lose charge after 40 miles. The remaining charge after 40 miles is enough so that, when accompanied by the engine's power generation, the car goes about 600 miles. When the battery is done, so is the trip.

One would think that the batteries are indeed getting charge from the engine after 40 miles... Because at times the electricity needed for propulsion will be less than what the engine can deliver, so the battery becomes a reservoir. And regenerative braking would have to add juice to the battery otherwise be lost. But that may be the news ... that the engine never adds anything to the battery and there are no supplemental regenerative systems. The engine and battery power are isolated. In which case, the engine will never add electric-only range to the car. It's 40 miles and no more. Even if you park the car after 40 miles with the engine on, the system may not be programmed or even wired to restore the battery for any additional electric-only range.

And here's where I'll make an educated guess ... the reason they'd do it that way is to extend the life of the battery, which is already the weakest reliability link on the car.

[ChevyRules]

Originally Posted by jbartley

this doesn't match the press release which talked about keeping the batteries between 30% and 80%...uhhhh riiighttt mr. journalist.

Sure it does. When the battery reaches 30%, it will start up the engine and will cease using the battery to power the electric motor. Then when you plug it in, it will charge the battery to 80%.

The remaining charge after 40 miles is enough so that, when accompanied by the engine's power generation, the car goes about 600 miles.

GM reduced the size of the fuel tank so it will be more like 360 miles.

[Wolfman01]

This is something that has always been known to those who have been following the car's development closely. That said, I do still hold out that there WILL be times when the engine would be able to shut down. That situation will be mountain driving. The batteries range will be altered somewhat by how much regen it receives. The power in regen mode needs to go somewhere, and that will be the battery.

If you are easy on the vehicle going up a hill, it is entirely conceivable that you'll get plenty of extra charge back into the system on the downhill side. As I've stated in a previous posts, I witnessed this very same situation in my '03 Prius. Toyota maintained tight controls on battery charge as well. Still on extended downhill stretches of highway, regen would be sufficient to bring the battery above the softwares normal high limit. In my case, the battery symbol on the video game display would go solid turqoise, and the car's software would then begin using the excess power to propel the vehicle.

The Volt will no more be exempt from physics than the Prius. If the battery SOC gets high enough, the system should conceivably shut down the engine, to allow the car to use this "excess" power to run in EV mode. These situations will however, NOT be considered in the normal range of driving for the vast majority of its owners.

[stevecmh]

i think we need official word for GM on this..

[rcracedriver]

It sounds to me that this method is designed to increase battery life AND fuel economy.

From wikipedia:
Unlike Ni-Cd batteries, lithium-ion batteries should be charged early and often. However, if they are not used for a long time, they should be brought to a charge level of around 40%–60%. Lithium-ion batteries should not be frequently fully discharged and recharged ("deep-cycled") like Ni-Cd batteries, but this is necessary after about every 30th recharge to recalibrate any external electronic "fuel gauge" (e. g. State Of Charge meter). This prevents the fuel gauge from showing an incorrect battery charge.[20]

So, therefore this method cuts out extra cylcles. My assumption is there's some ultra capacitors on board the volt that the gas engine is constantly topping off to deliver power to the motor after the batteries are drawn down.

Furthermore, if the gas engine were required to recharge the batteries, it would have to be more powerfull and suck more fuel to get it done. That being said, I think the engineers have done the right thing.

[pyropanda]

i refuse to believe that article unless the writer supplies us with a reliable source of some sort. it seems that the whole article was based on a biased interpretation of the sentence "a gasoline/E85-powered engine generator seamlessly provides electricity to power the Volt's electric drive unit while simultaneously sustaining the charge of the battery." the journalist interprets "simultaneously sustaining the charge of the battery" as shutting off the battery and using the engine so that "no additional power is drained from the batteries."

[Mcmflow]

I think we need to hear something offical......if this is true.....what a waste, I would never spend $35-40K for this

[DWade]

Why would anyone want to recharge the battery with the generator? The point of the gas motor is to extend the range, which means power the wheels. Its much more efficient to send the electricity straight from the engine/generator to the wheels then to send it into and then immediately out of the battery. In addition to being more efficient, it will also extend the battery life.

Its much cheaper to recharge the battery from the grid, and the whole point of the car is to reduce the amount of gas used. How would recharging the battery with gas help anything?

And the battery will be slightly recharged if the generator has extra capacity, but only up to a certain point, maybe 35%. Then the generator would turn off again, until the battery reached 30%, which the engineers call the customer depletion point. Then the generator would turn back on and the cycle would repeat. On the other hand, the battery may also be discharged even after the generator turns on, if extra power is needed, such as while accelerating quickly or going up a steep hill. After the power was drawn it would be replenished up to 30% again, in case extra power was needed later. This information comes from a graph that the Volt team released, that I think I saw on gm-volt.com.

As an engineering student who has closely followed the Volt's development, I can assure you that GM has done a very good job of choosing a charging strategy, as relates to efficiency, cost, and performance.

[2648562]

Originally Posted by megeebee

This is not what I had been thinking. It was my impression that the engine did indeed "charge", as in replenish, the battery.


.

Same here. I told a Toyota loving friend of mine that today too.

[FoMoCo Fan]

Originally Posted by slowinthefastlane

What about regenerative braking? Does that still charge the batteries when the engine is running?

I was going to ask the same thing. It would have to, I would think.

[zete]

I'm sure the Volt will turn off at a stop and also start up in electric, since during the coast the battery will be recharged somewhat. Since the generator operates at a constant speed it'll always be providing juice. When power demands are lower, the battery charge will go up. It has to. It's only logical. Question is, how much above the cutoff can the battery get charged? For that and a lot of other questions we'll have to wait until GM releases a production model for all of us to test.

[1931Chevy]

I dont know because if the car has a generator that means that while it gives power to the electric engine it can slowly recharge the batteries too or what am I missing here, I thought this could work like and alternator that when the engine kicks in the alternator starts recharging the battery and at the same time power the electric motor

[96_impala_ss]

I thought that was clear from the beginning. Drive 40 miles charge, drive 40 miles. if you run out of charge the motor kicks in until you can find a place to charge/go home w.e.

isnt the average commute 40 miles from point a to point b and back?
the car is good for the average 9-5 joe. its not ment to replace every car on the road.

so stop the whining.