Date: Sun, 30 Jul 2000 21:13:08 -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"
Yes Phil, that is correct - there should be a relay that prevents the fridge
from running on 12v unless the alternator is providing voltage at the D+
post. This is my understanding at least - I am sure Mark or Bill can
correct me if I am wrong.
As to aux. batteries - it seems that there are as many variations and ideas
as there are opinions about engine conversions. However, regardless of the
method used, I highly recommend aux. batteries (or battery). Nice knowing
that if you fall asleep with the lights and the stereo on that you will
still be able to start the van the next day...
Brent Christensen
'89 GL Syncro Westy
Santa Barbara, CA
----- Original Message -----
From: Phil Baird <mypactor@pacbell.net>
To: <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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