Hello-

I'm curious as to what voltages would be normal for 2 batteries w/ a
surepower isolator.  My main battery seems to have bitten the dust, I
killed it leaving the "headlights" (the parking lights, etc which remain
on after engine is turned off) on overnight.  The battery would take no
charge at all, I could start it from the aux battery, but it would take
no charge at all, after an hour of engine running.  So today I installed
a new battery, and things seem ok, for the moment.

My alternator puts out 13.8v.

Each of the batteries, with engine on, read 12.8 - 12.98

As I understand it, the voltage should be OVER 13 while engine is
running.  Engine off, the batteries are at 12.6 or 12.7

So the isolator is giving them each a little extra voltage, but not as
much as I would expect.  I am fairly new to DC electricity in vehicle
context, so if anyone can help me test to make sure my isolator is set
up properly, and my alternator is working correctly, I would appreciate
it.  I'm reading "Managing 12 Volts", which is a great book, but its
basically telling me I need to measure evertying at 80 degrees.

I'm paranoid that I screwed up the isolator install somehow, and the
batteries are just slowly draining (the install was a month ago, and
things seemed ok).

Thanks for any guidance-

Rob Campbell
87 Westy, Seattle