At 04:48 PM 6/16/2009, Loren Busch wrote:
>Don, please don't be insulted by this question but are you sure you are not
>reading the voltage at some point where the two batteries appear to be in
>series?  That's about the only way I can think of that would give such
>readings.

Right -- You won't see 20v from a 12v battery (engine off) no matter
what, even if it were being insanely overcharged and boiling
away.  Also it would burn out your lights quickly and likely fry the
ECU instantly.  So either the meter is way off or you're measuring
some combination of the two batteries.  The red light on the panel is
telling you that the house battery is toast.

The voltage you're seeing across the big relay terminals is the
difference in voltage between the two batteries.

>   Did you check the alternator output, when running AT the
>alternator?  I suppose that the regulator could be fried and the voltage
>could be that high from the alternator.  And even though you checked the
>meter against another I'd still suspect the meter.

Check the meter, on the same voltage range you used for the 12v
reading, against a dry cell, should be around 1.5-1.6 for a fresh one.

  --
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"