Staying Warm
There are several ways to heat the cabin of the vehicle. Because an internal combustion engine (in a gasoline powered car) produces a huge amount waste heat, there's a big issue in heating an electric car since this situation does not exist. For safety, the most important thing is to have the windshield clear from condensation caused by the driver's breath, which is warmer then the windshield glass. I decided I would add two electric heater cores that are found in inexpensive 120V AC electric heaters. These heaters have fans that require AC, but the heater element can run on either AC or DC, because it is a resistor. I had to get to my heater core in the vehicle which required disassembly of the dashboard. It was a difficult task, and I haven't put it all back together.
To connect the heater, I used a relay that tied into my 12 volt fan switch. When the fan switch is turned on, the 12 volts goes to the relay coil and pulls the 120 Volt DC line on. This allows the heater element to get current. I am using 2 elements out of 1800 Watt heaters. So if I have the heater on it uses 3.6kW. Typical driving uses 7.2kW, so my range would be decreased by 33%. Also, when it is colder, the batteries don't put out as much power. I decided not to use the heater, and to just dress appropriately. The hardest part was to keep the windshield clear. I realized if I opened up the small side vent windows, the windshield would stay clear. I tested this vehicle at -30F, and it was drivable without the heater.