pre-heating batteries in cold weather?

[acensor]

This may seem and odd time (spring in our hemisphere) to be broaching this topic,
but a friend who is wavering between getting a Leaf and one of the few remaining MiEV's touched on it. He's up in the mountains and from about 1 Nov to 1 April his EV (he currently has an ancient one hacked together out of a Geo Metro) sits in a very cold garage and the cold batteries don't like to accept charge and the very time when he'd be doing a long downhill glide and should be reaping lots of regen.

He noted that the Leaf has a battery pre-heater, and said the MiEV doesn't (unless you get a special cold-weather option.) Don't know if that's accurate. Thought (or assumed my SE and indeed all MiEV's had battery heating, as IIRR coolant circulates (hopefully intelligently around the batteries) heating and cooling as needed.

Any comments?

Also, way back last June (in a different topic on battery life) JoeS wrote --
"......the battery pack uses the cabin air for its heating/cooling, ..."

If so, it would seem that, regardless of anything else, he could prewarm his cold MiEV batteries by using the car cabin preheater with the remote. Right?

Or set the charging schedule to do a little charging (30 minutes?) before pulling out of the garage?

Alex

 

[JoeS]

acensor, "cold" as we know it in the West would be laughed at by our Canadian and Northern midwest iMiEV owners. Even the heaters on the specially-equipped iMiEVs with battery heating packages don't kick in until the temperature drops down to 15degF(?).

The circulating liquid coolant is not for the batteries but for the motor/controller/inverter.

Although there is an air duct from the passenger compartment into the battery compartment and we know there is a circulating fan in CHAdeMO-equipped iMiEVs, it is still unclear whether running aircon or heating in the cabin actually gets air forced through the battery compartment.

In any case, and in the interest of preserving our traction battery's energy, I think that most of us pre-heat or pre-cool our iMiEVs (using the Remote) before leaving home into lower or higher ambient temperatures.

Perhaps one of our northern friends can comment on regen degradation (if any) in low temperatures.

 

[aarond12]

It appears the LEAF's battery heater only kicks in at subzero temperatures like the i-MiEVs... and runs off battery power! :shock:

http://blogs.cars.com/kickingtires/2011/06/2012-nissan-leaf-battery-warmer-more-details.html

 

[jray3]

I've posted in other threads on this, but am pretty convinced that even us mild-winter Westerners would benefit from pack preheating, given the car's improved range now that daytime temps are above 60 degrees. I'm gonna run some numbers on heating my garage with gas or adding a radiant panel under the car for next winter. My goal would be to start the morning with a pack temp around 65 degrees F.

 

[acensor]

It appears the LEAF's battery heater only kicks in at subzero temperatures like the i-MiEVs... and runs off battery power! :shock:

http://blogs.cars.com/kickingtires/2011/06/2012-nissan-leaf-battery-warmer-more-details.html

OK, but what I still don't know is if the MiEV, or for that matter the Leaf's, electric battery preheater, which (as you and the link say) normally runs off the EV's battery power and kicks in only under extreme cold, will do the more intelligent thing. Which IMO would be to warm the battery off of household electric power?

Alex