NYT: Answering Your Questions About the Chevy Volt

[Omaha Steve]

I was reading about Obama's speech from last night and saw this.

http://wheels.blogs.nytimes.com/2009/11/24/answering-your-questions-about-the-chevy-volt/?ex=1275195600&en=48e7da62cf4503fd&ei=5087&WT.mc_id=AU-D-I-NYT-MOD-MOD-M125-ROS-1209-L1&WT.mc_ev=click

November 24, 2009, 8:23 am
Answering Your Questions About the Chevy Volt
By LINDSAY BROOKE

Last Friday, we solicited you for questions on the Chevrolet Volt, which is scheduled to be released late next year. We forwarded some of your questions to Lindsay Brooke, who recently drove a preproduction Volt and wrote about his impressions for the Automobiles section last Sunday.

Mr. Brooke is a journalist with three decades of experience and is the author of “Triumph Motorcycles in America” (Motorbooks, 1993) and “Ford Model T: The Car That Put the World on Wheels” (Motorbooks, 2008). He has written extensively on hybrid and electric cars for The Times and other publications. His answers to a selection of your Volt questions are below.
Q.

How will the batteries react to really cold weather? When it is 20 degrees below zero my iPod only functions for about one-sixth of its normal time between charges.
— Patrick, Minneapolis
A.

General Motors recently began an intensive cold-weather testing program for Volt at a dedicated site in northern Canada, so there are no definitive answers yet. Stay tuned for more information on this program in the Automobiles section.
Q.

What Mr. Brooke did not include in his article were any comments on acceleration performance once the Volt switched over to using the generator. Was the vehicle more sluggish or was the generator able to provide sufficient power to the battery so that the driver could not tell the difference between a fully charged battery and a depleted battery? If the test had been on a long uphill climb, would the generator have been able to continuously provide enough power to maintain speed? What will the expected miles per gallon be if making a long trip in gas-only mode? Regards.
— Mark, Rochester
A.

My test of the Volt prototype included numerous and varied elevation changes on the G.M. proving ground in Milford, Mich., including climbing a long 16 percent grade used for trailer-towing tests. The generator proved capable of propelling the car more than adequately in all driving situations. When in extended-range mode, the Volt’s acceleration felt similar to when the car was deriving its power exclusively from the battery. Fuel economy in the charge-maintaining mode is an unknown at this point.

FULL story at link.

[kristopher]

1. K&R

[Greyskye]

2. Nice.

Hope the Volt does well for GM.

I hadn't realized that the IC was used as a battery level maintenance device, as opposed to actually recharging the battery. Disappointing, but I understand that they had to make some compromises in the first gen.

It sounds very promising. As a very happy Prius owner, I think that the series hybrid powertrain is superior to the parallel system used by the Prius.

[wtmusic]

3. There's a physical reason why parallel hybrids are superior -

electric motors are more efficient at low rpms.

Though with a Volt you can, in theory, get 40 miles of efficient electrical power before you touch a drop of gas, you have to lug hundreds of pounds of IC equipment around doing absolutely nothing.

[Greyskye]

4. For those of us who drive < 40 miles/day...

...that particular disadvantage is pretty non-consequential.

[wtmusic]

5. We'll see.

If it had less pickup, inferior handling, and cost $15,000 more than your Prius would it still work for you?

[Greyskye]

8. I'm looking forward to the real world reviews.

And according to the review linked in the OP, it sounds like the pickup and handling are fine. I doubt it would handle worse than the Prius, which is strangely oversensitive and vulnerable to side winds.

And as much as I would love to contemplate the future purchase of a Volt, an electric or hybrid Persu, an Aptera, or even a GPS Electric Motorsport; getting laid off last April has squashed that fairly flat.

[wtmusic]

9. Me too.

No one would be happier than I if GM can pull this off, but on so many engineering fronts it seems like they're fighting an uphill battle.

[tinrobot]

7. Depends on the motor and how you define "high rpms"

DC motors are more efficient at low RPMs because high RPMs create magnetic field distortion of the field poles, causing "early back EMF" before brush contact. This can reduce power at higher RPMs. The standard electric car DC motors top put at about 5000rpm. Still, 0-5000rpm is a significant power band, and electric motors can be coupled to transmissions for higher speeds.

AC motors do not suffer EMF losses, have a much flatter torque curve and are actually more efficient at high RPMs. In fact, they're usually geared down in most hybrids and EVs. AC motors also can be used for regenerative braking, which recoups power for the batteries. All hybrids and planned electric cars use AC motors. They have plenty of power at higher RPMs and loads of torque on the low end.

Also, compared to gasoline motors, both DC and AC motors will be considerably more efficient. Electric motors can be as much as 90% efficient, where the best gasoline motors are 30% efficient, the rest lost to friction and heat.

[tinrobot]

6. It maintains the battery so gasoline isn't used to recharge it.

They could easily charge the battery from the gas engine, but choose not to because it's more efficient to charge the batteries from the grid than from the pump.