derekdrew@aol.com writes:
> 
> It is not advisable to use a dual battery isolator with you VW van. This is
> because isolators typically reduce the voltage by about 1 volt. 
> 
> [...]
> The solution is to use relays. There are 200/500 amp relays that you can buy
> and connect up to disconnect your batteries automatically for various
> scenerios. 

Derek is correct -- our Vanagon alternator puts out a little
less than 14V _at the alternator_ .  Because of this, not only 
is the forward voltage drop of the diodes in an isolator a
problem, but voltage drop across relay contacts and throughout
the system is a problem -- so use the best, lowest-resistance
relays you can find, and use big beefy cable.

Ted Zateslo
zateslo@geomag.gly.fsu.edu