Date:         Fri, 13 Oct 1995 14:11:00 -0700 (PDT)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Maher, Steve (SD-MS)" <SMAHER@PO2.GI.COM>
Subject:      RE: Electric Heaters / isolater



>    What is the deal with these solid state isolaters.  A guy at a
>local auto electric shop said solenoids are fine and cost A LOT less!!
>I would like to know if there is more to it.
>
>
>
>>

An isolator will automatically charge your second battery when the engine
runs, if you aren't drawing tons of current from it. If you start drawing
more current than the generator can supply, the isolator cuts off the
generator from the second battery, and lets the second battery supply the
current by discharging. Also, if your engine ISN'T running, the isolator
will let you draw current from the second battery, without running down
the first battery. So, you can run your heater until the second battery
is completely flat, but you can still stat the car later.

I believe a solenoid can do most of this, IF you remember to hand-switch
it every time. If you're forgetful like me, you might accidently run both
batteries flat, and/or toast your generator/regulator with too high a
current draw. If you're not as forgetful as I am, then a solenoid should
do fine.

 -Steve Maher   smaher@gi.com   '71 VW Transporter in San Diego--
                               what's a heater?