Date: Sun, 4 Nov 2007 07:13:25 -0800
Reply-To: Don Hanson <dhanson@GORGE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson@GORGE.NET>
Subject: Tracing Electrical fault in Coach battery system? (lotta words)
Content-Type: text/plain; charset="Windows-1252"
I am an electrical dunce.
Can someone give me some instruction on how to trace down a fault with my
aux. battery that's causing it to go down in about 24 hours? I have a
simple Radio Shack multimeter with scales for DCV, Ohm, DCA and ACV. My
batteries are <2mos old and have never been run totally flat, but close on
the coach battery just recently.
My van was sitting undriven for 2 days and I noticed as I passed my stereo
was 'beeping' at me, signifying low power. Took my meter (that I am just
learning) and tested the Aux. Batt. (which powers the stereo independent of
the ignition switch) and got 11.4 volts. Tested the vehicle engine batt and
got 12.94v. Started the van and the main battery read 13.9v, running. Went
to the coach battery, 13.8v. So it is charging (new alternator also)
Checked the function of the solenoid I am using..a canister type...that is
working also..
So, I put my battery charger onto the aux battery and left it overnight at
2amp setting..Tested in the am at 12.7 volts..the aux battery was 'isolated'
for that reading. Drive the van about an hour and still have a good reading
at the aux battery. Park it and re-test that aux battery in the
evening...about 12.3 volts in just 4 hours of sitting..The vehicle battery
was at about 12.8. Re-started and again got good charging readings at both
batteries..
So, something is drawing some juice and making that coach battery go flat,
but I don't know how to run down that short or fault or whatever you call
it. I have the following set-up:
The aux battery is fed by a big solid wire going directly to a canister
type solenoid under the driver seat and then (solenoid "out" terminal) to
the aux. battery terminal. That solenoid takes it's switching power from
the ignition switch from a lead that is hot only when the vehicle ignition
is on. Starting the vehicle causes the solenoid to de-power when the
starter is cranking, then switch back on . I also have a second toggle
switch in that solenoid 'control' circuit so that if my coach, or Aux batt.
should be dead flat, I can send power only to the main vehicle battery, not
both.
From the coach battery (under the driver seat) I have a big wire going to
a fuse block in the under-sink cabinet. That fuse block gives power to all
my electrical systems other than the normal vehicle operating systems.
(water pump, fridge, auxiliary interior lights, stereo, power outlets for
12v)
Each in-use terminal is fused. No fuses are blowing.
So, how do I find out which circuit is 'leaking electrons' and causing
that battery to drain? I should be able to use this millimeter to trace
where the power is escaping, right? Right now, I am thinking it may be the
stereo, which has a quite bright 'face' light that remains on (a small wire
is always 'hot' to retain the settings and run the clock). There is a
second wire for the main power..I have both these wires connected to the
same 20amp power terminal, always hot, powered from the coach battery.
..Last night, I removed that stereo fuse and re-connected the 2 amp trickle
charger to the aux battery. Right now, after removing the charger about 45
mins ago, I have a reading of 12.8 v on the aux battery after 10hrs at 2
amps. I plan on re-testing in a few hours, and if I get 12.8v again, I
probably found the circuit with the "leak" right?
It seems as if the stereo may be 'leaking juice'. How do I find that for
sure? I have tried (now, don't laugh, I said I was an electrical dunce..)
taking a reading from the lead > fuse block to the stereo...but it gives me
'battery voltage"...Should I put my tester on the stereo chassis and to
ground to see how much is moving through, or what?
Also, there may be some operator error on the stereo, because I have no
manual and have relied on the "infinite number of moneys, infinite
typewriters--eventually you get the Declaration of Independence" method of
re-learning how to make it work...pushing buttons till it does what I want,
and then remembering what I pushed for the next time. I have tried
everything to get the light to go off on the dial/faceplate of the
stereo..(A Sony MD/am/fm receiver) but it always stays lit up, unless you
"release" that face using a button supplied, and put it in the glove
box...An anti-theft feature, I suppose, that 'quick-release face" It may be
that leaving the face plate on draws too much current and it was designed to
always be removed..or perhaps having the main stereo lead connected to aa
always "hot", unswitched lead won't work with this unit..I wired it that way
so I could use the stereo off the Aux batt. without having the ignition key
on..Maybe I should put another toggle switch into that larger stereo lead
wire, and leave only the small 'maintain-settings/clock' power lead
unswitched?
Sorry for the length of this..
anybody wanna help a fellow who knows just enough about electrons to get
into trouble?
Don Hanson
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