Date: Sun, 30 Jul 2000 19:52:42 -0700
Reply-To: bpchristensen1@home.com
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Brent Christensen <bpchristensen1@home.com>
Subject: Re: Running fridge with an aux battery
Content-Type: text/plain; charset="iso-8859-1"
Bill:
Yes - I think you are absolutely correct - the fridge draws more amps than
the wire from the alternator can supply - well ,actually it is just
following the path of least resistance. If I am understanding the
schematics correctly, the fridge draws power from a 6mm wire directly from
the alternator (the feed circuit to the main battery) when there are no aux
batteries. With the aux battery setup, the shortest path to power becomes
the loop to the aux batteries, and they in turn are fed by the 6mm wire from
the alternator line.
I think what is called for is some sort of diode to prevent the flow of
current from the aux batteries, or a relay/transistor that can switch the
fridge to the starting battery/alternator circuit when the engine is
running, and then switch back to the aux batteries when in "camp" mode.
This would essentially work the reverse of the existing relay.
Does this all make sense? I'm pretty confident that the fridge is working
well, since I am not blowing fuses or creating weird puffs of smoke, etc.
:-)
Brent Christensen
'89 GL Syncro Westy
Santa Barbara, CA
----- Original Message -----
From: Bill Davidson <wdavidson@thegrid.net>
To: Brent Christensen <bpchristensen1@home.com>; <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, July 30, 2000 5:59 PM
Subject: Re: Running fridge with an aux battery
> Brent,
> Assuming that, like you say, the wiring is correct and the relay is
working
> properly ....
>
> My guess is that the fridge is just drawing more than is being supplied
> though the relay from your alternator... so it makes up the difference by
> drawing down the auxiliary battery...
>
> The stock wiring should easily supply the fridge since it was designed to
do
> so.... so what are the possibilities?....
>
> Could be you are drawing more than the 7 or 8 amps the fridge is supposed
to
> draw (perhaps other accessories... or even a short)...
>
> Could be the alternator is just not putting out enough juice to run the
> fridge and what ever else you are running off the starter battery
system...
>
> Both of the above?
>
> Easy enough to check... just use an ammeter in line between the auxiliary
> battery and the relay... start the engine, turn on the fridge and wee
what
> the alternator is supplying.
>
> Bill
>
> Easy enough to test
> ----- Original Message -----
> From: "Brent Christensen" <bpchristensen1@home.com>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Sunday, July 30, 2000 4:23 PM
> Subject: Running fridge with an aux battery
>
>
> > 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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