At 04:47 PM 2/5/97 -0700, you wrote:
>     Does anyone know what is in a battery isolator, the devices that let
>     one alternator charge 2 batteries on seperate circuits in a truck or
>     boat.  Is it low forward drop diodes or some kind of relay???

The diodes are not low drop. The voltage regulator monitors the actual
battery voltage and the alternator just produces a little more voltage. The
secondary battery is not directly regulated, just regulated because of its
similar connection.

-Bob