Or two 12 batteries in series less the unexplained 4v difference measured
from one battery's + to the other battery's +.
--
Mike "Rocket J Squirrel" Elliott

On 6/16/2009 5:49 PM jeff ensing wrote:

> If I had to venture a guess here I would say you are measuring both
> batteries in series somehow and one is 12+ - volts and the "coach battery"
> is 10 volts + -  ( Bad )  and is why your accessory's are not working.
> jeff
>
> On Tue, Jun 16, 2009 at 3:14 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
>>
>
>
>
> --
> Jeff Ensing
> Ensing Remodeling
> 3327 hidden acres Drive
> Atlanta, Ga. 30340
> 678-549-8430
>