TonyWilliams wrote:Oil pan heaters are the perfect combination for warming the battery.... we just need to keep the temps reasonable.
The biggest problem with an oil-pan heater is that it applies heat to a small area (couple square inches). What you need is a way to apply heat evenly to the whole surface of the battery box.
I guess that seemed obvious to me:
Yes, cover most of the metal bottom of the battery. That will require more than the size of a typical "oil pan". You can buy that stuff just about any size you want.
Item two, reduce heat output to 30-40C (80F-100F).
Three, don't put the heaters under electronic controls that we don't want to heat. I'd Use a big U pattern. I'm not worried about damage, just saving a couple bucks on heating pad material. I also probably wouldn't put the material on the bottom support beams.
Finally, run the appropriate size 120v through the motor compartment to the charging port, and label it "120v XXamp Aux Battery Heater".