> As Mr. Bill points out, though, there is almost always a down side.  In
> this case, the increased complexity of the control circuitry over a simple
> relay or diode isolator means more electronic parts to fail.

Maybe; maybe not. They're getting awfully good at making the electronics
these days... and these electronics may not be any more complicated that an
isolator... time will tell. But surely the most dependable option is the
ubiquitous automotive relay.

>But the
> enhanced performance and elimination of alternator overloading >likely
more  than compensates for this.

Maybe. But I'm not sure I buy the alternator overloading argument... even
for large wire 2nd battery set ups. After all, the VW engineers saw fit to
equip my van with A/C, headlights, radio, various heating and cooling fans,
etc... surely the 90 amp alternator was sized with all these accessories in
mind. And that 50 amp fuse on the A/C in particular tells me that if I have
a deeply discharged 2nd battery all I have to do is not use the A/C for an
hour or two after start up and the alternator should be just fine. :)

Bill

>
> Stanley
>