On  5 Feb 97 at 16:47, Brian Boles 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???
>
>     I would go for a newsgroup but our IS dept. won't set us up for that.
>
>     Rgds, Brian.                    bboles@microchip.com
>

In the UK for a second battery in a towed caravan a relay is usually
used. The relay is switched on when the ignition of the vehicle is
switched on, (ie. when the engine is running).

William Sadler