This is confusing. --- On Page 190 of my '90 Vanagon Westie owners manual, it says  "The auxiliary battery supplies power when the vehicle is stationary. A special relay between the vehicle battery and the auxiliary battery prevents the vehicle battery from discharging"

I figured that this meant the fridge on DC and the water pump, and the rear side cabin light (the one that looks like a flourescent light).

What does the factory installed Auxiliary battery actually operate?

Please try to help me out of my confusion.

Thanks,

Ralph