I have an 86 Wolfsburg Westfalia with the factory auxiliary battery.  The stereo is wired so that the key has to be in the �on� position to power it.  The other day I took the van to the local drive-in theater and had to leave the key on during the movie.  It did not seem like the best thing to do for an extended period.  I would like to power the radio with the aux battery.  The stereo is an old Sony cheapo tape deck.  The previous owner wired the power lead by pulling a fuse out of the fuse box, jamming the wire into the socket and replacing the fuse to hold it in place.  This is the circuit that has power with the key on.  I assume there is also another wire somewhere that retains memory in the stereo.

  I want to simply remove the hacked wire from the fuse box and run it to the aux battery with an inline fuse.  Can I leave the other power wire to the radio hooked to the main battery?  Will this cause some sort of weird loop that may inadvertently drain the main battery somehow?  My thought is that I can run the radio and refrigerator while camping and completely drain the battery but the stereo memory will still be retained.

  Also, is there any chance there are any wires in the fuse box area that run to the aux battery?  If I have to run a new wire, where is the best place to route it?