> Could you give us some more details on your relay set up? I'm still not
> sure
> what's wrong with the stock relay in the aux battery compartment as long
> as
> it's functioning as it's supposed to. Or is it a question of reliability?

Nothing really wrong with the stock relay, so long as you don't expect to
use the aux battery to start the Vanagon if your main battery craps out. I
understand there's also some possible issue with the wire size being less
than ideal  for efficient recharging, but I cannot say, as my van had no
stock relay.
 My setup is just an exercise in technical absurdity, really. It started
with wanting to be able to use the aux battery for starting, so I decided
the best bet there would be to put the battery as close to the starter as
possible. Under the rear bench on the slider side is about as close as you
can get without going into the engine compartment, plus the space there is
quite roomy so I didn't have to contend with the usual array of
Optima-battery-on-its-side compromises involved with putting it under the
driver's seat. Since I was using it as a starting battery and I'm a nut, I
decided to overdo it on the relay and wire size, thus the 2ga wire and 200A
relay. The solenoid was wired to connect when the engine was running. My
setup started off pretty simple, then it got silly. Rather than put the
solenoid directly on the alternator blue wire, I had the blue wire trigger a
relay, so I could have it optionally (switch controlled) fire the headlight
relays when the engine ran, Canadian style. But then I was worried about
loading the starting battery with a discharged aux battery AND headlights,
so I added a relay fired by the starter solenoid wire that DISconnects the
solenoid trigger. That's how it was set up when the relay clobbered my nice
expensive deep cycle battery. I have since replaced the big solenoid relay
with a smaller, more reliable unit, which no longer directly connects the
aux battery except when I want to use it for starting. The battery now
charges through a 3-stage charge controller. that connects to the
alternator/main battery circuit via yet another relay when the car is
running. Given some time, I'm sure I can find a way to shoehorn yet another
relay into the system.

--
John Bange
'90 Vanagon - "Geldsauger"