The straight poop on auxiliary battery setups can be found in the world of
Marine Electricity. All vessels of any decent size use two ( or more )
batteries. Not very nice to have only one battery so depleted that you can't
start your engine in an emergency situation. My advice to anyone
contemplating such a setup in a automobile would be to buy a good book on
marine electricity and study it.
Do not use relays. Use isolators, which are diode arrays with no
electro-mechanical parts. You can use a regular cranking battery if you
wish, and may want to start out this way, but it will have a rather short
life if you tend to deep discharge it. Deep cycle marine batteries are
probably your best bet. Consider a roof-mounted solar array also.
Chuck
'83 Westy
'84 Jaguar XJ-6 VDP
'86 Buick Skyhawk Hatchback
-----Original Message-----
From: Dawn Bustanoby <dawnmb@OZ.NET>
To: vanagon@GERRY.VANAGON.COM <vanagon@GERRY.VANAGON.COM>
Date: Friday, June 28, 2002 1:21 PM
Subject: Auxilary battery

Hi everyone,  I'm a delighted new owner of a '91 Vanagon Westfalia.

I have been doing a lot of research on auxiliary batteries.  I'd like to
install one to run the kitchen, camper light, and car stereo.  I've read
several articles and seem to have found conflicting information.

So please, can someone point me in the right direction?  Deep cycle battery
or regular car battery (my VW mechanic says to use a regular battery)?
Battery Isolator or relay (and really I don't  understand the difference in
detail)?  What about Optima batteries (and which one do you use?).

Sorry if this subject has been beaten to death in the list.  Feel free to
refer me to the appropriate archives.

Thanks!
Dawn Bustanoby
Seattle