Yes - you need to isolate the two batteries from each = other, otherwise one will drain the other if there is even the = slightest difference in voltage.  (They will try to equalize each = other).  This can have catastrophic effect due to the amount of = current that can suddenly surge through the wiring.

Traditional "battery isolators" don't work = well in a Vanagon due to the voltage drop.  (Didn't work well in = my old Jeep, either - wish I'd thought about the relay trick back = then).  You need to separate the two batteries with a stout relay = (I have a 75 amp relay) that is only switched on when the alternator is = kicking out juice.  Then power all your accessories from your aux. = battery by shunting to the hot side of the #3 fuse terminal.

Takes a bit of crawling around and snaking wires, but = well worth it.  I wish I'd been willing to give up the space under = the seat for a pair of golf cart batteries!

Brent Christensen
'89 GL Syncro Westy
Santa Barbara, CA

> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.C= OM]On Behalf
> Of Jay L Snyder
> Sent: Monday, April 03, 2000 10:08 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Battery Under Back Seat
>
>
> I am thinking about installing a battery under = the rear seat by simply
> running a heavy wire to the starter (which = would in turn
> connect it to the
> existing battery) and grounding to engine or = chassis.  Would
> I need fusible
> link/fuse on this wire?  What gauge = wire?  I realize this
> will only give me
> additional power when cranking or with ignition = switch on.  This setup
> seems too easy--am I missing something?
>          = ;            = ;            = ;            = ;           = Jay
>