A 150 watt electric heater will draw 12.5 amps and produce appeox 512BTUs of heat. That is a LOT of current for a TINY amount of heat. This is why cars don’t use electricity to produce heat. A typical automotive heater (which uses the FREE heat produced by running the engine puts out 20,000 or so BTUs. You will need 40 of these electric heaters to get that kind of heat. Also, 40 heaters will pull 500 amps… so you will also need at least 2 ambulance-grade alternators, and several large 12v batteries to store the energy, and lots of 0 gauge wire.
Or buy this thing, be immensely disappointed, and then throw it away.