To clarify: The traction motor, DC-DC converter (charges the 12V battery while driving and while charging the traction battery), resistance cabin heater, compressor for heat pump or air conditioner, and internal traction battery heaters (if equipped) are powered by the traction battery. Everything else is powered directly by the 12V system (including fans, coolant pumps, entertainment/navigation system, power steering, power brakes, and lights).