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Re: NREL : Impact of Climate Control in Electric Drive Vehic

Posted: Sat Aug 06, 2011 12:52 pm
by aqn
The paper's synopsis refers to both pre-conditioning (heating or cooling) the cabin, as well as pre-conditioning the battery:

"Preconditioning the battery also has a positive impact. [...]
"Pre-cooling the battery in conjunction with cabin cooling represents a partial solution.
"

It's unclear to me in the case of the LEAF, having no "climate control" for the battery, whether/how much of those findings would apply... But, the paper does look fairly scholarly and credible, and I would believe its findings, if I ever bother to read it its entirety!

Re: NREL : Impact of Climate Control in Electric Drive Vehic

Posted: Sun Aug 07, 2011 3:02 am
by planet4ever
aqn wrote:It's unclear to me in the case of the LEAF, having no "climate control" for the battery, whether/how much of those findings would apply... But, the paper does look fairly scholarly and credible, and I would believe its findings, if I ever bother to read it its entirety!
I'm not trying to impugn this article, but a scholarly appearance doesn't guarantee good science. As for whether their findings would apply to the LEAF, their EV case was specifically an attempt to model the LEAF.
evnow wrote:You are making the mistake of equaliting cooling/heating the cabin with cooling/heating the battery. Not the same at all. As the report title says - this is about climate control for the people in the cabin.
That's not my mistake, but it may be a mistake in the report. They are the ones claiming (see their figure 7) that for their simulation of a LEAF, driving with the battery at 95 degrees Fahrenheit will cause a 3.9% annual capacity loss in the battery, whereas if you precondition the car - and by that I assume they mean precool the cabin, since that's all you can precool - there will be only a 3.6% annual capacity loss.

If they mean some kind of preconditioning other than the cabin then they aren't talking about a LEAF, they have contradicted the conditions of their table 1, and their conclusions don't apply to the LEAF. The progressive capacity loss is the only significant precooling advantage I could see in their EV case, so I am left with two choices:
  1. Their calculated capacity loss doesn't apply to us, so there is little if any advantage to precooling.
  2. Their calculated capacity loss does apply, so I should always run the A/C while driving on hot days to save the battery.
Note: Heating is a whole 'nother story. I'm only talking about cooling.

Ray

Re: NREL : Impact of Climate Control in Electric Drive Vehic

Posted: Sun Aug 07, 2011 10:15 am
by evnow
planet4ever wrote:That's not my mistake, but it may be a mistake in the report. They are the ones claiming (see their figure 7) that for their simulation of a LEAF, driving with the battery at 95 degrees Fahrenheit will cause a 3.9% annual capacity loss in the battery, whereas if you precondition the car - and by that I assume they mean precool the cabin, since that's all you can precool - there will be only a 3.6% annual capacity loss.
Well, it has been 6 months since I posted the article - so don't remember every bit ...