[Oeva-list] EVs in the winter?

[Gary Graunke]

Hi,

I don't drive my Insight EV in the snow just because there is a higher 
risk of accidents--I take my "store bought" car in the ice and snow. I 
spent a half year of my spare time converting it, and almost that much 
again building my 6 batteries from 230 cells each. Doing it again would 
be much quicker, and by now I could probably just buy batteries like 
everyone else.

However, I still drive my EV to work even in cold weather. They are 
better than ICE in cold weather, except that having a heat engine when 
it is cold gives you lots of "free" heat (normally wasted) which you 
might appreciate. They don't have to warm up (though you might have 
battery heaters that would change this a bit)--I don't. The electric 
motor does not have to warm up to "start"--it just works. You may use 
some heat to defrost the windows or yourself. I have a 2KW heater, and 
my car uses 10KW for freeway driving.

If you have lead batteries with no insulation or heater, they will lose 
half their capacity in cold weather. So your range is half or less (due 
to using some for heat in your electric heater). NiCd batteries don't 
care at all. Li Ion will lose some power, and that may cause them to 
lose capacity if you are marginal on the power to begin with. But these 
don't change the efficiency much. Plowing through slush will lose 
efficiency equally well for ICE and EV vehicles. Headwinds are equally 
bad for both. So it's a matter of having enough range to cover extra 
losses from rain, slush, or wind.

Using A123 LiFePO4 cells, I get pretty much the same range in the cold. 
I drove 30 miles last new years eve, and have the voltage and 
temperature log. However, it does not log the watt-hours so you get the 
WH/mi data. I did notice the voltage drop a bit more in the cold when I 
went over a large hill. The batteries lose some power, but the A123's 
have more than ample power and are really stiff (minimal voltage drop 
under load) even in the cold.

For your hybrid, turn off the defrost and heat while idling, so the 
engine shuts off as it does in normal weather. Remember that 10% of the 
fuel in winter is ethanol for air pollution purposes, and that has about 
60% of the same energy per gallon. So you have about 4% less energy per 
gallon.

Actually, in the last few days people have been driving slower and 
accelerating and stopping more gradually. If they did this all the time, 
they would be much better mileage even with ICE vehicles. We EV folks 
often do this to get our range up so we get where we want to go.

Gary


Kristen Hall-Geisler wrote:
> Hi all -- 
>
> I'm curious about driving EVs in winter weather like we've had here in Portland recently. How do they fare? Better, worse, or the same as an ICE? Do they start okay on frigid mornings? Do they get the same number of miles per charge as usual? Have you guys been commuting in your EVs this week, or have you gotten out the conventional vehicles while the roads are nasty and the temps are low? 
>
> I've been test driving hybrids lately for GoodGreenCars.com, and it seems like when the weather turned bad, the car's fuel economy got worse. It made me wonder about straight-up EVs and their winter performance, so I figured I'd ask the folks on the list for their experiences. - khg
>
>
> Kristen Hall-Geisler
> freelance writer | Portland, Oregon
> 503.975.0306 | kristenhallgeisler.com
>
>   
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