[pnieder]

I'm writing an article about the Volt. I need a technically correct/sourced answer to a question. In a posting on this site from August '07 (NEW FACT: Volt generator starts when power hits 50%, stops again at 80%) it confirms that the generator (when running) will recharge the batteries to 80%. That means that only 20% of the charge will be available for recharging during the pug-in mode. This seems substantially less than is usually intimated. I understand this would only happen during usage cycles when the generator kicks in, but can someone either confirm this, or provide updated info?

Also, the actual electric energy consumption info I have found on this site states .3kwh/mile. This is the same as I have found stated for the Tesla Roadster, which is a much smaller vehicle with a substantially lower frontal area (drag). I am a bit skeptical about this claim for the Volt. If it's not true, range will be substantialy affected. Any comments?

 

[Eric E]

Generator/SOC details

This is the most accurate info we have to date. (That I'm aware of)

The "range extender" will definitely NOT charge the battery more than approx 35-40% soc (state of charge). Which makes sense, as the goal is to require the car to be plugged in when not in use. The purpose of the range extender is to maintain the battery at a 25-35% soc while providing power to operate the vehicle and all accessories.

Please see the graph at this link:
http://www.motortrend.com/features/auto_news/2008/112_0804_chevrolet_volt_update/photo_03.html

 

[pnieder]

That contradicts the August posting, and it's not absolutely clear if that chart's baseline is zero. It makes sense, but ifanyone has more explicit info, I would be glad to see it. Thanks.

 

[Texas]

Perhaps you can read the post I wrote about how the set points are calculated (I use the analogy of a barrel):

http://www.gm-volt.com/forum/showthread.php?t=204

From my post you will understand that the set points will change depending on conditions and drivers. The numbers you presented would make no sense at all in most situations. You would ideally like to drive into your charging station at the lowest point of charge. Correct? Otherwise, you would be using gasoline where the grid electricity is more desirable.

Nobody here would be able to give you exact numbers, not even the Volt engineers, because those numbers will change after the final design is on the road and all of the software and testing has been completed. Additionally, the set points will change for different conditions including the aging of the battery pack. Finally, I think they will be using settings that are initially conservative in order to achieve 40 miles of capability at the end of the lifecycle of the battery. Many conditions, many changes. Sorry there is no easy answer.

 

[Eric E]

Actually the entire thread that Texas recommends you look at pertains to your question.

 

[nlh_90210]

bang bang

I think the best analogy for how I expect the ICE in operation is like a heater. When the charge gets to the lower set point the ICE turns on, when it get to the upper set point it turns off, much like a thermostat. That way you can run the ICE at a constant rpm, with a constant torque to the generator. That way the ICE can be optimized for fuel efficiency at those two parameters. I'd be very surprised if they made anything more complex than that. Think of the ICE as an electric generator instead of a motor.

In general I would not quote any of us, especially if you are writing an article. All of this is speculation.