Marine supply stores sell a boat dual battery switch.  It is a fairly
large item- about the size of a soup bowl.  You run both positives from
your batteries to this switch, and then a common wire from the switch to
your starter selenoid terminal.  The switch has 4 settings - off, an on
for either battery, and an on for both batteries.  It allows you to use
either battery, none, or both.  I use this with a marine deep cycle as
my aux, switching the aux in camp, then back to either both or the main
when I go to start up and leave.

Due to the size, I paced the aux and switch under the rear seat in my 82.

david

dave bowers wrote:
> Hey Folks,
>
> I managed to kill the primary battery on my 1986 Westy while I was camping.
> Getting it restarted (jumped) was a piece of cake. I simply connected my
> jumper cables to my aux batt. and "vrrrrrooooom."
>
> While I was jumping my self (so to speak), I wondered .... is there a safe
> way to hardwire a proper gauge wire from the positive terminal of my Aux.
> batt. to the pos. terminal of my primary batt with a switch in between?
>
> The idea being, should I kill my battery again, I could just throw the
> switch, start the car then flip the switch back. There seems to be enough
> room in the center walkway to run a coated wire from batt. to batt. under
> the matt, and perhaps even under the center isle.
>
> Has anyone tried this? I realized our batteries are each grounded well, that
> when one goes to jump themselves (so to speak) that you don't even have to
> use the black cable.
>
> I don't have plans to kill my battery any more, tho this is the kind of
> project I'd like to have set up, if it's safe to do.  Comments? Suggestions?
> Opinions? Recommendations? I'm on vacation, and have the free time. Lemme
> know what you think.
>
> Thanks much,
>
> dave-o :)
> _______________
>
> dave bowers
> Portland, Oregon
> 1986 Westy "HMS Beagle"
> http://www.dave-bowers.com/vw