[T2] troubleshooting auxiliary battery charge

[david raistrick]

> In other words - I don't really get how the whole charging aux battery system works - nor what runs off the aux battery. Does the Aux battery power certain things inside, or does it work in parallel with the main battery, to just give you power for a longer period of time between re-charging?

this one is easy:

yes!

or hard actually:  yes.   it could do any of those things, it depends
on how it was wired up by whoever wired it up.

you're probably going to have to track down all the wiring associated
with the aux battery and figure it out.      take some pictures of the
components you run into (isolators, relays, diodes, switches), and
sketch where the wires go and approx size.  "8g wire goes to primary
battery +"  "12g wire goes into interior of bus from XYZ post of
mystery box 1"

there have been many kits sold over the years (and still for sale) by
vw vendors, probably worth looking at the install diagrams for some of
those to see if any of them match up to what you have.