West Marine makes a solid state BC.  (apologies if this was already covered
as I missed the beginnig of this thread)

Brian

----- Original Message -----
From: "harald_nancy" <harald_nancy@earthlink.net>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, August 10, 2000 7:40 PM
Subject: Re: Battery isolator vs combiner??

> Ken,
> I called Sure Power a few months ago, and they also told me
> that their isolator is more efficient than their combiner in the
> vanagon application.
> The technician claimed that the combiner is actually less
> efficient, because of the power loss across the contacts.
> (They would make more money selling combiners.)
> Makes you wonder about relays.
> I've been using Sure Power isolators in different vanagons,
> '81 air cooled and '90 model, for many years.
> For me, the SP isolator works very well in the vanagon
> installation.
> Here are the voltage measurements I get on my '90 westy
> with the 90 amp alternator.
> Engine compartment:
> voltage at alternator:             14.84
> voltage at battery 1 terminal: 14.14
> voltage at battery 2 terminal: 14.14
>
> Front of the vanagon:
> voltage at aux. battery:          14.2
> voltage at main battery:         14.2
> voltage at outlet in dash:       13.95
>
> That's with a 1 year old Bosch regulator, and had my original
> alternator rebuilt by a local shop.
> You can see how the voltage drops on its way to the dash.
> When I turn on the headlights and other accesories, the
> voltage drops even more at the dash, all the way down
> to close to 12.5 volts, in extremes.
> But that's because of the wiring in the vanagon.
> At the battery terminals, the voltage stays around 14.2.
> Overall, these measurements are very acceptable to me.
> I never have any dead battery or charging system problems.
>
> It might be somewhat more marginal with the 65 amp
> alternator on the older models. But I've previously used the
> SP isolator on my '81 vanagon, and it did ok.
> The 65 amp alternator has to be in good condition to keep two
> batteries charged, and the batteries also have to be in good condition.
> I don't know how it would work with a 45 amp alternator (diesel??).
> Looks like you have a diesel westy.
> I think the isolator works very well with the 90 amp alternator,
> and both batteries last a long time (like 6 yrs +).
> The Sure Power model that I'm using is 1202R.
> Good luck.
> Harald
> '90 westy
>
> Ken wrote:
> > Being in the mood to install a 2nd battery in my 82 Westy, I have been
> > reading the archives about the SurePower isolator and the more recently
> > mentioned combiner. The drawback to the isolator I had assumed to be
> about a
> > .7 volt loss in charging and some modification to the alternator
> regulator.
> > The battery combiner seemed to be the ticket as it didn't have these
> problems
> > and in addition could (optionally) be used to combine the 2 batteries
for
> > emergency starting. The SurePower people tell me, however, that for
> Vanagons
> > the best choice is the isolator and that the supposed .7 volt charging
> loss
> > is actually compensated by increasing the charging rate the same amount.
> Also
> > the isolator being solid-state would last longer and be more trouble
free
> > than the electo-mechanical combiner besides being half the cost.
> > Looking at the West Marine catalog the isolator again is mentioned as
> losing
> > that .7 volt and not being the best way to go.
> > I am probably going to use a deep cycle lead acid battery until I can
> afford
> > the spiral-wound or gel cells. What am I missing here? Is the isolator
> OK?
> >
> > Ken Hunter
> > 82 Westy 1.9D
> > 84 Jetta 1.5D
> > 89 Mitsubishi van