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Charging power used to keep battery warm in winter

Posted: Sun Feb 10, 2013 11:33 am
by MrSustainable
I have been logging the power used by my Voltec charging station to correlate energy used to maintain the battery temperature in the COLD Maine winter. It seems that the Volt needs to draw power of 1500 to 2500Watts (at 240V) for brief bursts of under 10 minutes fairly often when the temperatures drop below 20F. Below are some charts from my loggers so you can compare temperature with energy used to warn the battery. We did not drive the Volt for the last 2 days because it was snowbound by over 2ft of snow (storm Nemo). It's not a LOT of power, but a clear reminder that it is wise to leave the Volt plugged in.

You can see current charts on my Chevy Volt page:

When we are driving in sub 20F weather, the engine generator comes on about 25% of the time with a dash warning: "ENGINE RUNNING DUE TO TEMPERATURE". According to my DashDAQ it is keeping the battery coolant above about 40F.

Re: Charging power used to keep battery warm in winter

Posted: Sun Feb 10, 2013 12:41 pm
by PatrickZWang
Very interesting! btw how does the Volt do in snow? Do you use chains / cables at all or don't take the car out? I am thinking about taking it up to the mountains but want to know if that is a good idea. (Sorry this is coming from the California guy, our winter right now is 55 degrees...)

I'm wondering if warming the pack has more to do with it being "ready to go" or if it actually helps maintain the longevity of the pack.


Re: Charging power used to keep battery warm in winter

Posted: Sun Feb 10, 2013 1:40 pm
by MrSustainable
Hey Patrick,
Winter driving is fine - for those of us that are used to it. We do not use chains or snow tires and the traction control is very good. But I must warn you that driving in snow is an acquired skill that you have to learn the hard way. Coming form California myself (I lived in Oakland and Vallejo) I had to be very careful my first few winters. So take it easy when you get to driving in snow and try some practice skids in a parking lot or back road first to get familiar with front wheel drive skids and traction control etc.

I was on a snow/slush covered road on a gentle curve recently going a cautious 25MPH when I felt the rear end slip sideways recently. I let up on the accelerator and steered into it and came out OK, but by easing off, I caused the front end to slip too (I was in L mode) and that could have made things MUCH worse at higher speeds. Remember ABS will not engage when you are regen braking.

I have heard that if the battery gets too cold, the vehicle will not let you drive until the ICE has warmed up the battery. This is an issue intrinsic to lithium battery technology. It damages the battery if you draw power from it when it is below freezing, same for higher temperatures.