Date:         Wed, 29 Oct 1997 23:07:21 -0800
Reply-To:     "harald.nancy" <harald.nancy@MCI2000.COM>
Sender:       Vanagon mailing list <Vanagon@Gerry.SDSC.EDU>
From:         "harald.nancy" <harald.nancy@MCI2000.COM>
Subject:      Re: Charging Second Battery
Content-type: text/plain; charset=ISO-8859-1

> John wrote on Oct.29:
> Harald,
>
> Speaking just for myself, I think I am more confused after your last post
> about your 2nd battery installation than I was before. If you left the
> frig as before, does that mean you are not running the frig from the aux.
> battery?
>
> Maybe when you have a chance sometime you could post a little diagram. I
think
> I would not be the only one interested. I guess I can understand about
the
> isolator. I am not sure how you are actually charging the two batteries.

Sorry if this is so confusing. I have a '90 westy with the refrigerator
with
the 12 volt heating element, propane gas, and 110 volt heating element.
The 12 volt heating element is only used while driving, since the power
drain is too big when the engine is not running. It would drain any battery
very fast. That is why the original vw small relay under the driver's seat
turns off the 12 volt power to the frig when the car is not running.
I left that original vw relay system intact, since I don't want to drain
the secondary battery unnecessarily. When the camper is parked, I switch to
propane or 110 volt.
Since the frig 12 volt heater element turns off when the car is not
running, it doesn't matter to which battery it is connected. For
convenience, I did hook it up to the
secondary battery, but did not change the basic relay setup. I installed
another
fuse panel connected to the positive of the secondary battery, to which one
can hook up anything.
You just have to run new wires.

Once the secondary battery and isolator are in place, it is up to you how
to
connect it to the appliances. See Bentley Vanagon '91 camper page 97.33b
for wiring diagrams. I disconnected the red wire on terminal 87 on the
relay
under the seat and hooked that terminal up to the positive of the secondary
battery. It is the only wire to change on the relay. It connects the sink
and fridge. Now you can use the other end of that disconnected terminal 87
red wire which goes to the dash by the fuse panel and disconnect it there.
Now you have a wire from the secondary battery to under the dash. You can
use it to splice in the radio and interior lights. My note in the Bentley
book (page 97.201 for fuse relay panel diagram) says that I cut B12 (radio,
lights, clock), spliced B12 to red wire coming from second battery under
passenger seat from terminal 87 on the relay. Don't forget to install a new
fuse when you hook that red wire up to the secondary battery.
Terminal 85 r/bk on the relay stays as is. It tells the relay when to turn
on/off.
Don't tackle this if you don't understand it 100%. I have to admit that
it's rather confusing, but it works on my vanagon.

Regarding the multi-battery isolator:
It's some kind of a solid-state relay mounted in a heat-sink.
The dimensions are approximately 4" x 4".
Instructions and diagrams are included in the box from Sure Power.
I installed mine in the engine compartment behind the right rear wheel
well.

It has 4 terminals. No. 1 terminal is connected to the main battery
(basically, you remove all the wires that are hooked up to alternator
output originally and then connect them to the No. 1 terminal)
No. 2 terminal goes to the second battery. I use a #6 gauge wire to the
secondary
battery, as recommended, with a 40 amp circuit breaker in between. No. 3
terminal goes to the alternator output. One small terminal is hooked up to
the regulator.

The isolator senses the charging state of each battery, and recharges
whichever battery needs charging the most. Basically, when you're driving,
both batteries are being charged very efficiently, with the main battery
taking
precedence until it is full.
While camping, the appliances are discharging the secondary battery only.
The main battery remains isolated and is not discharged.
When you are driving again, the secondary battery seems to charge up pretty
fast again, since the system is very efficient. I never bothered with
trickle chargers.

Some auto electric, battery, or rv shops can order them from the company.

                                          Sure Power Industries, Inc.
                                          Tualatin, Oregon 97062
                                          phone (503) 692-5360
                                          fax (503) 692-9091
The model for vanagons must be for the Bosch alternator.
If you have the big 90 amp alternator on the later vanagons,
only use model number 1202R, maximum 120 amp.
On the air-cooled vanagon smaller alternators, you can use
model number 952R, maximum 95 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.

I hope that I wrote down all the terminal numbers right in my notes. Make
sure to double-check with a circuit tester and follow the diagrams in
Bentley. Disconnect both batteries when you work on the system.

Harald
'90 westy