Hey,
There are two schools of thought on this one...Yes, there is a Switch
kit available (try www.BusDepot.com) that allows a second battery. it
is isolated via a relay and charges when the ignition switch is on. Or
you can go with the Isolater option. Both work well. Remember though
if you install a second battery for auxillary items, you really should
use a Deep Cycle RV battery...Sounds like you should use the Isolator
Option for the application your wanting. Try (
http://www.geocities.com/harald_nancy/ ) for more second battery
options and info..Good luck

On 24 Oct 2005 12:24:06 -0700, "Colm" > wrote:

>Hi
>I need to add a 2nd auxillary battery to my 83 Watercooled westfalia
>camper. I will be using it primarily to run my laptop and maybe a
>light.
>
>I understand that the battery will fit under the driver's seat. I
>ordered an aux. battery kit from gowesty but I have a few questions.
>
>If I have two batteries do I need an Isolator?
>
>Here's someone saying I do.
>"A dual-battery-relay is a simple switch,
>disconnecting the two batteries, when the engine is turned off.
>But the moment the relay reconnects the batteries, the
>drained battery robs power from the starting battery.
>This sudden transfer of current from one battery to another
>can damage batteries, and shorten their life.
>
>A solenoid will disconnect batteries form one another, but the second
>the solenoid reconnects the batteries there is a sudden discharge from
>the main battery to the aux. This shortens battery life and can leave
>you with two dead batteries or worse - a fire."
>
>I want to charge the auxiliary battery when the engine is runnig.
>I don't want the auxiliary battery to rob current from the main battery
>as described above.
>
>Do I have to have both batteries connected to each other?
>Why don't I just connect the auxiliary directly to wherever the main
>battery gets its source from.?
>
>I'm looking for the best, simplest and most inexpensive solution. Any
>ideas?
>
>How do I hook up some sort of voltage indicator so I can see what kind
>of charge the aux is holding?
>
>I have looked at the solution at vanagon.com but need more info.
>
>Thank