Battery tsroubles

N

neely butler

New member
Sep 28, 1998
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Last week, after several days of unattendance, I tried to start the GMC,
batt dead, clicked aux batt switch several times, finally it allowed me to
start the engine. Went to local Advance Auto store, they checked batt,
advised that alternator was OK, must be batt, installed new batt, drove
about 40 miles and parked her at home, this AM tried to start, dead batt,
and aux batt would not engage with rocker switch. Battery charger on at
this time. My diagnoses, something must be draining the "truck" battery
and the relay that engages the "house" battery must be not working.
Comments please.
Neely B. TN
 
I had a similar problem that only showed up in the cold
months. Previous owner had installed a household
thermostat, which has no off switch, to control the
furnace. Any time temp got below 50 degrees, the blower
motor would kick on. A piece of cardboard between the
contacts was my quick fix.

Dave Hilsdorf
Bellevue NE
1973 260

...
> this time. My diagnoses, something must be draining the
> "truck" battery
...
> Comments please.
> Neely B. TN

=====
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My battey drain was a faulty radio/cassette player. It would drain the
batteries in 2 days flat!
The problem was solved with transplant surgery.

John '76 Palm Beach, Omaha

Previous owner had installed a household
> thermostat, which has no off switch, to control the
> furnace. Any time temp got below 50 degrees, the blower
> motor would kick on. A piece of cardboard between the
> contacts was my quick fix.

> ...
> > this time. My diagnoses, something must be draining the
> > "truck" battery
 
Neely,

It all comes down to current paths, there is a current path in the chassis
wiring that allows the battery to be drained. The simple way to trouble
shoot this condition is to disconnect the battery and use an OHM meter to
find the current path. Hook the meter to the pos. & neg. terminals and
disconnect wires to the pos. side until the meter shows open.

Check this out first, if the diode pack in thed alternator were partially
shorted it would still show charging to a non suspecting person. If the
chassis leg of the isolator were shorted as well, it would allow the
battery to discharge rather quickly if the alternator & the isolator were
both shot! Hook up the meter as described and unbolt the center wire on the
isolator. If the meter shows open when you do this, that is your trouble.
I see this more often than I thought I would. The isolator could have been
shot for some time and the diode pack in the alt. made the condition
invisible. When the alt. diodes got tired of doing the isolators job and
went home, your trouble came to the surface.

Hope this helps,

Jim Bounds
- ------------------------

>Last week, after several days of unattendance, I tried to start the GMC,
>batt dead, clicked aux batt switch several times, finally it allowed me to
>start the engine. Went to local Advance Auto store, they checked batt,
>advised that alternator was OK, must be batt, installed new batt, drove
>about 40 miles and parked her at home, this AM tried to start, dead batt,
>and aux batt would not engage with rocker switch. Battery charger on at
>this time. My diagnoses, something must be draining the "truck" battery
>and the relay that engages the "house" battery must be not working.
>Comments please.
>Neely B. TN
>
>
>
 
Jim just a small point. Dont think you meant to use the ohms function of
the multimeter to check for current drain. If there is one it could burn
the meter out. Use the current function.

>Neely,
>
>It all comes down to current paths, there is a current path in the chassis
>wiring that allows the battery to be drained. The simple way to trouble
>shoot this condition is to disconnect the battery and use an OHM meter to
>find the current path. Hook the meter to the pos. & neg. terminals and
>disconnect wires to the pos. side until the meter shows open.
>
>Check this out first, if the diode pack in thed alternator were partially
>shorted it would still show charging to a non suspecting person. If the
>chassis leg of the isolator were shorted as well, it would allow the
>battery to discharge rather quickly if the alternator & the isolator were
>both shot! Hook up the meter as described and unbolt the center wire on the
>isolator. If the meter shows open when you do this, that is your trouble.
>I see this more often than I thought I would. The isolator could have been
>shot for some time and the diode pack in the alt. made the condition
>invisible. When the alt. diodes got tired of doing the isolators job and
>went home, your trouble came to the surface.
>
>Hope this helps,
>
>Jim Bounds
>------------------------

>>Last week, after several days of unattendance, I tried to start the GMC,
>>batt dead, clicked aux batt switch several times, finally it allowed me to
>>start the engine. Went to local Advance Auto store, they checked batt,
>>advised that alternator was OK, must be batt, installed new batt, drove
>>about 40 miles and parked her at home, this AM tried to start, dead batt,
>>and aux batt would not engage with rocker switch. Battery charger on at
>>this time. My diagnoses, something must be draining the "truck" battery
>>and the relay that engages the "house" battery must be not working.
>>Comments please.
>>Neely B. TN
>>
>>
>>
>
>
 
>Jim just a small point. Dont think you meant to use the ohms function of
>the multimeter to check for current drain. If there is one it could burn
>the meter out. Use the current function.

Tom,

Jim specified to remove the leads from the battery first. As a result, it's
perfectly fine to use the Ohm meter to hunt for shorts. His diagnostic
procedure boils down to looking for low resitance (relatively speaking)
circuits that would be connected to the battery.

Using the ohm meter avoids the need to install a shunt in the circuit (or
have an expensive meter with a hefty built in shunt).

Henry

Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (831) 462-5199 / full service marketing
fax: (831) 462-5198
http://www.henry-davis.com/ http://www.henry-davis.com
 
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