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Re: battery heater and days subzero parking

Posted: Tue Jan 02, 2018 6:01 pm
by LeftieBiker
The heaters only use about 300 watts, so they just aren't suited to warming the battery to a better operating temp. They can only stop the pack from "freezing."

Re: battery heater and days subzero parking

Posted: Tue Jan 02, 2018 6:10 pm
by BrockWI
I thought I read somewhere you could alter the thermostat to trick the car in to thinking it was colder than it was, say by 10F or 20F, but it would be nice to have it come on for say 2 hours while charging to warm the pack up. I know charging warms it a bit, but then I am lucky to see 3 bars instead of 2. Starting out at 4 bars would be nice :)

I know there was a thread with someone using oil pan heaters to warm the pack up.

Re: battery heater and days subzero parking

Posted: Tue Jan 02, 2018 10:41 pm
by LeftieBiker
BrockWI wrote:I thought I read somewhere you could alter the thermostat to trick the car in to thinking it was colder than it was, say by 10F or 20F, but it would be nice to have it come on for say 2 hours while charging to warm the pack up. I know charging warms it a bit, but then I am lucky to see 3 bars instead of 2. Starting out at 4 bars would be nice :)

I know there was a thread with someone using oil pan heaters to warm the pack up.
Yes on the oil pan heaters, but the tricked thermostat mod is for the Volt, to lower the temp at which the ICE starts.

Re: battery heater and days subzero parking

Posted: Wed Jan 03, 2018 4:14 am
by arnis
LeftieBiker wrote:The heaters only use about 300 watts, so they just aren't suited to warming the battery to a better operating temp. They can only stop the pack from "freezing."
300W is more than enough to heat the battery way above ambient. It just takes hours instead of minutes.
I estimate at least 10-15 degrees (metric) above ambient is reachable with the heating elements Leaf has.
Yes, if it is -40*C, Leaf battery will still freeze. Though this temperature is not available for long enough
where Leaf is actually sold.

Unfortunately, there is no known way to operate battery heater except opening the pack to change the temperature
sensor resistance values, so the heater will operate according to modified values. No wires come out of the pack.
I would like to switch it on myself as battery efficiency drops when there are less than 4 temperature bars.
And here where I live, I've been down to 2 bars (below -5*C inside the pack) many times. Even down to 1 bar.

Re: battery heater and days subzero parking

Posted: Thu Jan 04, 2018 10:10 pm
by Levenkay
arnis wrote: 300W is more than enough to heat the battery way above ambient. It just takes hours instead of minutes.
As scathing an indictment of the pack's poor cooling as I could imagine. What's needed is a way to *defeat* that kind of thermal insulation during the summer.

Re: battery heater and days subzero parking

Posted: Fri Jan 05, 2018 12:04 pm
by Dooglas
Levenkay wrote:As scathing an indictment of the pack's poor cooling as I could imagine. What's needed is a way to *defeat* that kind of thermal insulation during the summer.
What kind of pack cooling problems have you experienced in Portland, OR?

Re: battery heater and days subzero parking

Posted: Fri Jan 05, 2018 1:48 pm
by Levenkay
Dooglas wrote:
Levenkay wrote:As scathing an indictment of the pack's poor cooling as I could imagine. What's needed is a way to *defeat* that kind of thermal insulation during the summer.
What kind of pack cooling problems have you experienced in Portland, OR?
Hitting 9 temperature bars (about 5 bars of "rise") during a multiple-QC journey from Bellingham to Portland in mid-40 degree F weather. I haven't bothered to chase down exact numbers, but isn't that about a 50 or 60 degree difference between the pack and a highway-speed airflow? I have to believe that even a modest forced-circulation liquid heat exchange system would get the heat out with way less temperature drop, and still let the pack stay insulated in cold environments (just don't run the circulation pump in that case).

Re: battery heater and days subzero parking

Posted: Fri Jan 05, 2018 1:55 pm
by BrockWI
I know the e-NV200 uses cooling, I believe it is just forced air and in one trip a youtuber did LOTS of fast charging and didn't see the kind of rise in temps that he saw with his Leaf. Granted passive cooling will help when it's not already 90F outside, but passive is better than nothing.

https://www.youtube.com/watch?v=P9bHw0PS3uM

Re: battery heater and days subzero parking

Posted: Fri Jan 05, 2018 7:02 pm
by jjeff
Cool video, a bit long but interesting none the less. Active cooling on a Nissan!

Re: battery heater and days subzero parking

Posted: Fri Jan 05, 2018 10:41 pm
by arnis
9 temperature bars very "temporarily" is absolutely fine. Don't worry.
Just don't do this every week for years.