RE: Second Battery
Proper installation of the aux battery in  Westfalia camper moves the water
pump and the refrigerator (fused in the little black box beside the drivers
side door) to the aux battery.  For the interior lights, dash board cigar
lighter and radio, they remain on the starting battery.  They can be moved
with little trouble.  The exact wiring changes depend on the year of your
Vanagon.