Batteries keeps dying

Clone TIE Pilot

Royal Smart Person
Aug 14, 2011
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#1
Over the last year I kept having this problem of batteries dying in my Regal. Not just draining but also going bad and no longer holding a charge. Today I did a few checks for drains or shorts in the electrical system. First I disconnect the neg battery cable and connected a test light in series between the neg cable and terminal, tiny spark but no light, and the bulb is working. Next took out my multimeter, hooked it up the same way as the test light. It indicated there was 12 volts present, but only 17.7 milliamps, so likely just the small drain for the ECM and radio memory. Not enough amps to light the test light. I tried pulling all the fuses one at a time as well as disconnecting the pos lead to the alternator and no change in the readings. Not sure what else it could be?
 

TURNA

Comic Book Super Hero
Jul 24, 2009
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#2
While you were testing the batt and pulling fuses did you leave the door open?
 

Wageslave

G-Body Guru
Jan 25, 2017
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#3
You might try unplugging your alternators 2-pin connector, and see if your draw drops down. If it does, it might be the diode pack in the alternator leaking current.
 

foxtrot

Royal Smart Person
Dec 19, 2008
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#4
Maybe you have two issues. I'm thinking that the issue with the battery not holding a charge could just be a defective battery and nothing to do with the car. As far as the battery drain issue, maybe you have an intermittent issue because the 17.7 mA from the ECM & radio would take a year to drain the battery.

My Regal had a battery drain issue for years that I temporarily solved by keeping the battery tender connected when the car wasn't in use. One day I did decide to troubleshoot the issue with the DVM/fuse method that you utilized. My DVM also showed relatively very little current draw off the battery when the car was 'sleeping'. I was at a loss but one of the times when I had the DVM connected in series with the battery, I noticed a draw of a few amps. The draw of a few amps only lasted 30 seconds or so and then went away. It turns out the old security system from the 80's would 'wake up' from time to time and draw a few amps of current. I disconnected the old alarm system and the battery has held it's change ever since.

Maybe your Regal has a similar issue?
 

Clone TIE Pilot

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Aug 14, 2011
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#5
I had the doors closed for all the tests. I disconnected the line from the battery to the alternator for one test, but did not try disconnecting the two wires for the regulator. I am on my 3rd battery this year that has died and stopped holding a charge, tried different brands too. My car does not have a alarm system in it.
 

Jeff L

Master Mechanic
Nov 20, 2016
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#6
Years ago I had a battery drain issue I had similar trouble with. In that car it was some wires where the insulation was frayed and they were touching. I had to put in a new wire harness because other wires were also deteriorating. Did not look bad visually until I dug into it and noticed that some wires were drying out, if that is the term for the insulation becoming brittle.

Never had a fuse blow out. This car was pre computer and one of the wires exposed was always “hot” and would drain the battery overnight like leaving your lights on.

Once the harness was replaced and wires checked no other issues.

Something in your car might ge doing the same thing?
 

Clone TIE Pilot

Royal Smart Person
Aug 14, 2011
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#8
I tried unplugging the two pin connector for the alternator and no change. Probably going to be a few days before I can try pontiacgp's method. My Regal has two metal breakers, guess for those circuits just pull the breakers and touch the probes to the socket contacts?
 

Clone TIE Pilot

Royal Smart Person
Aug 14, 2011
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#9
Its been awhile, I tried the procedure pontiacgp posted and all the circuits went to 0 indicating they are ok. Maybe just a string of bad luck with batteries? Other thing is the current alternator is a pretty new Autozone reman 12si, maybe something wrong with it? Read some reports of AZ alternators not operating correctly despite passing common tests.
 

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