Date: Tue, 16 Jun 2009 13:57:31 -0700
Reply-To: neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: neil N <musomuso@GMAIL.COM>
Subject: Re: Battery/Charging system questions.. A lot of info included..
In-Reply-To: <6bc66ccf0906161214ne92e438m514576b4b4a5b887@mail.gmail.com>
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On Tue, Jun 16, 2009 at 12:14 PM, Don Hanson<dhanson928@gmail.com> wrote:
> From a dummy...
>
> The last few months my coach battery hasn't seemed to be staying charged
> up as well as in the past. I've changed nothing recently.
> So I got out my handy dandy Radio Shack digital meter today and began
> poking around. I find lots of Volts. Dunno what it should be, but I seem
> to have too many at the Vehicle battery and plenty at the Coach
> battery..however, my water pump is kinda slow and the Westie Indicator
> lights are on the Red bulb most of the time (when the engine is not
> running)..
> My system:
> I have two identical NAPA batts. of around the same vintage (aug '07)
> These are "sure start 65" BCI 42 with 500cca and 250amps. One under the
> passenger seat (the vehicle batt) and the Coach batt under the driver's
> seat. I have a big wire (fused, of course) across (vehicle to coach batt)
> which feeds a big 'mechanical' can 3 terminal relay, also under the drivers
> seat. This relay is controlled by a wire from the ignition and the wire is
> also switched (that supply wire from the ignition to the relay)...I wasn't
> sure about starting the vanand how the two batteries would inter react
> during start up, so I began by having that secondary switch off whenever I
> started up...That proved to be un-necessary but it is nice to be able to cut
> the power to the secondary battery without shutting off the van..
> Ok, so I run the van and check the relay...Flip the switch from the
> ignition to excite the relay and "Click!" it works fine..
> But the numbers (from my digital meter) don't make sense....Oh yeah, when
> the van is running, the Westie stove-front power indicator light goes
> Green...engine off..Red...on Green.
> From my digital meter: Vehicle battery..Van off reads 20.6 Van running
> reads 21.8
> Coach battery...Van off reads 17.3 Van
> running and relay active reads 21.7
> I double checked with an older analog meter and my Radio Shack one is
> functioning fine...though I wasn't sure which scale to read on the analog
> meter, it is consistent with the digital one.
> So how come so many volts? Is this bad? Or is my meter simply screwy or
> my testing technique faulty?
> Also, across my 'mechanical' relay (a silver cylinder with two (+/_) large
> terminals and a 'supply' terminal..I am seeing (I think) some current when
> there shouldn't be any. I see about 4 volts across the two main (+ (in from
> the vehicle battery) and -(out to the accessories in the coach))
> connections. That shouldn't be, unless perhaps the relay is now faulty?
> Anybody care to take a shot at this weirdness?
> I am thinking I probably have a couple of things going on here..Maybe my
> meter is reading wrong and maybe the relay is faulty.
>
> The setup has worked pretty well for me for about 18 months including a
> prolonged (4 months) outing where the Van was used as a second bedroom and
> work/play vehicle daily..I would get about 2.5 hrs of satellite radio,
> incandescent light and some computer time before my coach battery went
> down...At present, I'd guess maybe I'd be getting about 1/4 that, so
> something is out of whack somewhere...I know I could have a more appropriate
> electrical system but I don't want to re-do the whole thing right now.
>
> Don Hanson
>
Hi Don.
First thing I'd suggest, is getting a digital VOM to replace your
analogue VOM. Not knocking analogue, just easier to read. And as they
say, RTM, so you know how to measure DC in the correct range etc. :)
As for the switch/can arrangement, I would imagine the switch is there
so that when starting the van, you are not risking having both
batteries connected to each other and would only be drawing from the
starter battery. Normally there is a relay instead of "can", that is
triggered on by the blue wire from the alternator. This way batteries
are connected only when engine running. i.e. not connected when ign
switch turned to 15 (ign. on)
It sounds like you're using standard automotive type battery for your
house battery. A lot of people do this. But, they tend not to be as
forgiving as, say, a deep cycle battery. Especially when it comes to
amount of discharges, and how far they get discharged. From what I've
read, a deep cycle battery, if not discharged beyond a certain point
(less than 80% IIRC) can withstand being discharged more times than a
standard automotive type battery.
It may just be that your house battery has seen better days.
Have you tried charging it with a charger?
Neil.
--
Neil Nicholson '81 VanaJetta 2.0 "Jaco"
http://tubaneil.googlepages.com/
http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
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