Date: Sun, 30 Jul 2000 20:16:16 -0700
Reply-To: Mark Drillock <drillock@earthlink.net>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Drillock <drillock@earthlink.net>
Subject: Re: Running fridge with an aux battery
Content-Type: text/plain; charset=us-ascii
This sounds like a current limitation of the relay and/or wiring you are
using. The other choice would be that your aux bat has a problem. Check
the voltage right at each battery with the engine running and the fridge
off. Then turn the fridge to 12 volts and see what the voltage at the
aux battery is. Much of a drop would indicate that insufficient current
is available in the aux circuit to run the load and charge the aux bat
at the same time. Heavier wiring and relay may be needed or there may be
a weak connection. I prefer a heavy duty setup with soldered on cable
ends and screw on terminals.
I use #8 marine grade wire and a 100 amp continuos duty relay when I
install aux batts. This allows me to recharge the aux battery quickly
when camping just by running the engine for a short time. I use an
identical battery in both positions. I don't change the stock
battery/alternator wiring at all, just run a #8 with a soldered on lug
from the clamp bolt of the main battery to the threaded stud of the
relay. Another #8 runs from the relay to the aux battery. I control the
relay with a wire from the Westy kitchen fuse panel behind the driver
seat. One of these 2 fuses only has power when the engine is running and
there is room to add another wire to the screw clamp at the output side
of this fuse. In a pinch I can use the aux battery to aid the starter
batter. This is easily done by momentarily jumpering between the fuse
ends so the battery relay is activated even without alternator charge
sense current.
There are other ways people do aux battery setups but this way is
simple, inexpensive, and leaves the original wiring intact. It also
allows for using the aux battery to help the starter, or even running
the Vanagon on the aux with the starter battery removed. I have used
this method on several Campers over 7 years and I have had no problems.
Any high current wiring work should be performed by someone who knows
what they are doing. There is a lot of energy available from a car
battery.
Brent Christensen wrote:
>
> OK, just when you thought there could be no more written about this
> subject...
>
> Here's a tricky one for y'all:
>
> I have a pair of auxiliary batteries wired up using the stock relay and
> harness (yes, yes, they are wired correctly). The lead from the starting
> battery attaches to terminal 30 of the relay, and the fridge and auxiliary
> batteries are attached to the two #87 terminals. Everything works dandy,
> and has for over a year now, with one exception. If I want to run the
> fridge on 12v while underway, it now pulls from the aux. batteries rather
> than the alternator. (I have found this to be empirically true, since I
> have arrived at camp with the aux batteries drained down to 50% or so after
> driving a couple of hours with the fridge set to 12v)
>
> After poring over the Bentley wiring schematics, this seems to be a design
> limitation. (Needless to say, I drive around with the fridge running on
> propane when going to a camp site) Or am I missing something?
>
> Any brilliant ideas on modifying the wiring so that the fridge would run
> from the aux. batteries while camped, but from the alternator while
> underway?
>
> BTW, whatever solution I (we) come up with will be documented (with
> pictures) on www.vanagon.com for the enjoyment of the community...
>
> Thanks!
>
> Brent Christensen
> '89 GL Syncro Westy "Klaus"
> Santa Barbara, CA
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