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.COM]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
>

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