Author Topic: Mysterious Battery Drain  (Read 4550 times)

Offline RusTy/SE

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Mysterious Battery Drain
« on: March 31, 2012 - 08:52:27 AM »
The vehicle is my 86 D250 and the issue is an voltage drain on the battery with the ignition off, key out.

Should the computer (located behind the battery in the fender cavity) be pulling any power?
« Last Edit: March 31, 2012 - 08:55:46 AM by RusTy/SE »
Russ
2001 Durango     1B4HS
1970 Challenger  JS29U
Restoration thread: http://www.cuda-challenger.com/cc/index.php?topic=27173.0
Member since December 13, 2002




Offline Bullitt-

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Re: Mysterious Battery Drain
« Reply #1 on: March 31, 2012 - 09:49:57 AM »
Hey Russ... I have no 1st hand knowledge of your model but know some electronics do draw a small amount to maintain memories, radios & PCMs for example. Unless there is an internal short I would not think they would be a problem.

I did a few searches & while it has nothing to do with your problem I found this....
Truck only starts with Headlights ON!  Never heard of or thought it possible.
http://www.dodgetalk.com/forums/archive/index.php/t-187779.html
« Last Edit: March 31, 2012 - 09:52:20 AM by Bullitt- »
Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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Offline RusTy/SE

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Re: Mysterious Battery Drain
« Reply #2 on: March 31, 2012 - 12:22:15 PM »
Thanks Wade, my knowledge regarding electrical systems, like so many, is weak at best. I know there must be a power source, a ground, and clean connections, but little in the way of troubleshooting. That's why my my neighbor Bob has taken the lead on this episode. Although he's a ringer for the Geico caveman, he's like Good Will Hunting where mechanicals and electrical systems are concerned; in between systematic testing he offers up layman-like explanations to help my understanding.

With Bob's help and and welcome instruction (ASE certified in brakes, tune-up, and alectrical through 1986 when he was at that time employed at a local Goodyear) we connected a multi meter yesterday evening and proceeded to go through each fuse with no change in volts. We also checked direct current items such as dome and cargo lights and door switch to rule those out.

The computer has two pin connectors, one large and one small; when unplugging the smaller of the two, there is no voltage drop. When unplugging the larger of the two, volt reading drops from 12 to 5 1/2. When connecting to a spare computer I have, there is no drop. We made sure this second computer was grounded at the time for an accurate reading.

Accordng to Bob, with the ignition off nothing should be pulling any power from the battery so we both believe that the computer is the thief causing my battery draindown issues and i'll be instaling that second one in a little while.
« Last Edit: March 31, 2012 - 12:24:01 PM by RusTy/SE »
Russ
2001 Durango     1B4HS
1970 Challenger  JS29U
Restoration thread: http://www.cuda-challenger.com/cc/index.php?topic=27173.0
Member since December 13, 2002

Offline 426HEMI

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Re: Mysterious Battery Drain
« Reply #3 on: March 31, 2012 - 01:17:12 PM »
Russ,  I would put either a test light or a dvom in between the negative cable and the battery.  Take one fuse out at a time to find where the voltage draw is gong and it will be easier to trace it.  Hope this helps some.  It is hard to diagnose without being there but I hope I can help you.  Gordon
Got a pretty good start on my M46 optioned Barracuda restoration but now it is on hold till I can gather more funds.  Still need a few parts for it.  SIU Graduate 75 AAS Automotive Tech, 94 BS Advanced Tech Studies, 1997 MSED Workforce Education and Development

1970 M46 Barracuda
1998 Dodge Darango

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Offline 06Daytona

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Re: Mysterious Battery Drain
« Reply #4 on: March 31, 2012 - 01:49:51 PM »
How long does it take to kill the battery? My Charger and truck both need to be fired up once a week or so, or else the battery gets pretty low and I have to jump them.
1972 Cuda 340 4 barrel 4 speed that looks like a 71
2006 Dodge Charger R/T Daytona
2005 Dodge Ram 2500 Diesel 4X4
2006 Chrysler PT Cruiser Convertible (Kidmobile)
1972 Dodge Charger 318 auto
1970 Challenger 440/727 auto
1973 Plymouth Duster 340/auto (Making it Panther Pink for the wife)
2006 Honda Civic Hybrid (It doesn't save gas, it just diverts it to the Cuda/Challenger)
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Offline Chryco Psycho

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Re: Mysterious Battery Drain
« Reply #5 on: March 31, 2012 - 11:26:49 PM »
could be a draw in the Alt , what about stupid things like a glove box light ?
 try removing all the fuses & see if the draw stops .

Challenger - You`ll wish You Hadn`t

Offline RusTy/SE

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Re: Mysterious Battery Drain
« Reply #6 on: April 01, 2012 - 10:16:10 AM »
Russ,  I would put either a test light or a dvom in between the negative cable and the battery.  Take one fuse out at a time to find where the voltage draw is gong and it will be easier to trace it.  Hope this helps some.  It is hard to diagnose without being there but I hope I can help you.  Gordon

could be a draw in the Alt , what about stupid things like a glove box light ?
 try removing all the fuses & see if the draw stops .

Exactly what we did.  :2thumbs:  First I was inside pulling fuses with no change, later we reversed with Bob pulling the fuses (to double check) without change. We also unplugged the vr with no change, the alternator with no change. The doors were closed, no glove box light or other closed circuit drawing power.

I installed a spare 'spark' computer and now with it unplugged the drain pushed up to 8 volts. However when we disconnect the white connector coming off the positive battery cable (see pic), voltage drops to zero. Bob exlained that this is the cause of the slow battery drain. According to the fsm it goes to the ignition switch. If I understand correctly, the ignition switch should pull no power until the key is in and turned to either the auxillary or on position.
« Last Edit: April 01, 2012 - 10:19:06 AM by RusTy/SE »
Russ
2001 Durango     1B4HS
1970 Challenger  JS29U
Restoration thread: http://www.cuda-challenger.com/cc/index.php?topic=27173.0
Member since December 13, 2002

Offline Chryco Psycho

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Re: Mysterious Battery Drain
« Reply #7 on: April 01, 2012 - 10:26:34 AM »
White wire ?? all I see is 2 black & a red !!
there are power feeds from the battery that bypass the switch , things like dome lights , lighter circuits , the alt , clock / radio memory etc ,

Challenger - You`ll wish You Hadn`t

Offline RusTy/SE

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Re: Mysterious Battery Drain
« Reply #8 on: April 01, 2012 - 10:37:24 AM »
My first camera went dead transfering the pic to my pc; I had used an older pic of the area. Second camera worked fine and here's the correct pic showing the disconnected wire.
Russ
2001 Durango     1B4HS
1970 Challenger  JS29U
Restoration thread: http://www.cuda-challenger.com/cc/index.php?topic=27173.0
Member since December 13, 2002

Offline Chryco Psycho

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Re: Mysterious Battery Drain
« Reply #9 on: April 01, 2012 - 01:12:02 PM »
so thast is the main power plug to the inside of the vehicle

Challenger - You`ll wish You Hadn`t