Loren and everybody else -

Thanks for the clear responses, that's an easy check - I'll do it this weekend.  My spare battery is good and does hold a charge, the aux that came with the car I haven't checked - I'm just assuming it's fried.  I'll refill the cells that are low in fluid and put on a trickle charger to see if it charges and holds a charge.

So, If I understand this right, the way the stock aux system works there is a relay that connects both batteries when the engine is on (and thus both charge), and disconnects them when the engine is off (thus the aux battery runs anything by itself until it's dead).  Is that right? 

Dan
Los Angeles, CA
'85 Westy Weekender

On Jul 12, 2011, at 2:25 PM, Loren Busch wrote:

> RE: Is the Aux Battery Charging?
> Assuming you have a multimeter.  Install the new aux battery.  Put the meter
> on it, a fully charged lead-acid battery should read 12.4 to 12.6 volts.
> Start the engine and make sure the Alt light goes out.  With the engine
> idling put the meter on the aux battery again.  You should see right around
> 14 volts but at the minimum 13 volts or more.  If not then check the
> starting battery, again with the engine at idle.  You should see the higher
> voltage (directly from the alternator) there.  If the aux battery is not
> charging then the problem is going to be in the wiring between the starting
> battery and the aux battery, either the wiring or the relay that connects
> thte two batteries with the engine running but disconnects then with the
> engine off.