Matthew,
I've been using the SurePower battery isolator on
all my vw campers throughout the years.
I just followed the SurePower instructions installing them.
On the alternator, all you have to do is take out the regulator,
bend over the little copper tab, solder the wire onto it, and hook it
up to the R terminal on the isolator. It is actually very easy,
and doesn't bother the alternator in any way.
You can also always reverse the installation.

I found that with the isolator, the batteries can last a long time.
My original Varta battery on my '90 westy lasted until last year.
On the smaller 75 amp (?) alternator, I used the model
number 952R isolator, maximum 95 amp.
On my '90 westy with the 90 amp alternator, I now use
model number 1202R, maximum 120 amp.

My 1990 vanagon burned out the 952R, so I replaced it after 4 years
with the stronger 1202R. When it broke, all it did was connect both
batteries.

There was a really interesting thread on isolators versus relays, etc.
a couple of years back. You can read it in the archives under
title "Re:Charging Second Battery", dates "10/28/97 8:28 pm
to 10/30/97 4:14 pm". There is also a posting that I wrote
with my isolator installation notes under author "harald.nancy"
on 10/29/97 11:07pm.

Hope this helps.
Harald
'90 westy

Matthew wrote:
> I have a SurePower battery isolator. It is of the solid state (as opposed
to
> relay) variety. It is made for vanagons specifically.  Has anybody had
any
> experience with installing these jobbies? The instructions call for some
> alternator tinkering, why? Can some one explain what the internal
regulator
> does and why that function needs to be routed to the isolator.  Will this
> tinkering jeopardize the integrity and reliability of my alternator?
>
> How does the VW isolator work? Where is it connected and to what? Is this
> something that someone with some electrical background can quickly
fashion ?