Date: Mon, 31 Jul 2000 07:44:07 -0700
Reply-To: Bill Davidson <wdavidson@thegrid.net>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bill Davidson <wdavidson@thegrid.net>
Subject: Re: Running fridge with an aux battery
Content-Type: text/plain; charset="iso-8859-1"
Phil,
Yes, the with a stock set up the fridge only gets 12 v power when then
engine is running.... the alternator sends a signal to the fridge relay to
close the circuit, thus connecting fridge to alternator via the starter
battery and starter.
Bill
----- Original Message -----
From: "Phil Baird" <mypactor@pacbell.net>
To: "Bill Davidson" <wdavidson@thegrid.net>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, July 30, 2000 8:46 PM
Subject: Re: Running fridge with an aux battery
> Excuse my ignorance, but I just may have learned something. Am I to
assume,
> gentlemen, that the 12v power option on the frig only works while the
engine is
> running?.....assuming, ofcourse, that I don't have an aux. battery?
>
> ....Phil in Bakersfield
> '85 Westy
>
> Bill Davidson wrote:
>
> > > 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.
> >
> > No. I would expect your wire to be 2.5mm (per Bentley) unless you have a
> > weekender that originally came with an auxiliary battery (then it would
be 6
> > mm per Bentley). The Westies imported into the U.S. did not come with an
> > auxilary battery option so they did not wire them for that... Also, the
> > alternator power does not go directly to the auxiliary battery unless
> > someone changed the stock wiring... it goes: alternator> starter >
starter
> > battery > main fuse panel > under carpet between seats to auxilary
battery
> > box and fridge relay.
> >
> > Still, 2.5 mm wire is sufficient to supply the 7 or 8 amps to the
fridge...
> > unless there is something wrong with the wiring or the relay or the
> > alternator..
> >
> > >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?
> >
> > No. If the alternator is supplying enough power and the wires and relay
are
> > delivering it, the fridge will run off it and not draw down the
auxiliary
> > battery. I have a relay system and do no have the problem you are
> > describing.
> >
> > You're assuming that your system is working properly but poorly
designed...
> > This is not the case. The relay system will work properly... there is
just
> > something wrong with the wiring or the alternator.
> >
> > Do the ammeter test I suggested in the previous post... find the
problem.
> >
> > Bill
> >
> > >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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