Keep the thinking cap on! Yes, that would probably work but.....the heater in the car can produce more energy. Scenario 1: run a line for engine fluid to a spot near the battery vent and use heated fluid from the engine blowing through a tiny radiator to heat the batteries more directly. Scenario 2. Insulate the motor for winter use with the rad blocking mod. This will allow the engine to run hotter in the winter. The inside of the car will be warmer as a result and the air from the passenger compartment that gets sucked in to the battery area through the duct behind the passenger seat will be warmer effectively heating the batteries more. Just my 2 cents worth.
