No need to use wire that large. 8 gauge is plenty. The larger stuff is
much harder to work with in tight spaces like Vanagon battery compartments.

You did not say what year and model you have so I can't say what
connection point is best for you to control the relay from.

Mark

Kai Mei wrote:
> i'm going to use a stancor relay and heavy wire (0 or 2 ga) and I'd
> like to know how to parallel the batteries only when the ignition is
> on AND alt light is off which I haven't seen how to do in my research.
>
> The van currently has zero wiring in the aux battery area.
>