I happened upon your thread on Battery heaters in "Flexi-Watt Battery Heater Control System". I am very interested because I own a few of the GE Elek-Trak Garden tractors. I live in NW Ohio so It gets very cold here in the winter. I was researching a way to heat them. It sounds like you have the ticket. I would like to know if it is possible to obtain the schematic and code you are currently using, as I wish to apply this to my situation. I am not a designer, but can follow a plan.
Many thanks in advance, and keep up the good work!