The loss of potential across the diode is negligible. I still get up
to 13.7 volts on my aux. read directly off the posts and it is
monitored continuously. I get 14.2 volts simultaneously on the main.
        So yes there is loss , but so what, my aux. is a AGM and
float levels are to be less anyway.
                                David

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

>High current diodes are great, in theory, and will keep current flowing in the
>correct direction.  But they have a problem when it comes to 12V multi-battery
>charging systems.  That is, the forward voltage drop will likely be over a
>volt, depending upon actual current.  How do you compensate for that?
>
>//Jack
>
>
>Date sent:              Wed, 21 Feb 2007 18:49:34 -0700
>From:                   David Etter <detter@MAIL.AURACOM.COM>
>
>>  If the main battery was depleted, having my aux. battery on a 10ga.
>>  wire from the alternator with an inline 50amp diode prevents the aux
>>  battery backing up into the main battery through the alternator
>>  connection. Thus you will not ruin the aux. battery attempting to
>>  equalize the depleted Main.