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Unknown circuit or something causing battery drain. Sporatic

Tags:
  • Battery
  • Engine
Last response: in Cars
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February 5, 2014 11:22:05 AM

I have a 98 Buick Park Avenue that lived a life with a mechanic so
most of the engine components have been changed, etc.

The car runs fine, there is zero check engine issues, starts, fine, stereo is stock
GM stereo.

I have no idea what is causing battery drain. There will be some mornings where the
battery has just enough juice to open the door and that Is it.

I have replaced the battery, tested alternator (so it is charging), ensured the lights
are all off, door shut, truck shut, etc.

On the web people say to run voltage tests across the battery. If there is a drain
by say a light on you should see voltage dropping. I don't when I test my battery.

For example of a situation:

Go out in the morning, battery is dead unable to start car. So unlock the door with
remote that is fine. Starter clicks, not enough power to start. Hook up battery charger
and give it 20 min on 15amp to provide enough to start.

Starts...
Drop off friend to work, come home and park car. Put Volt meter on 20VDC across the battery
and watch it. It stays currently at 12.38v (This was this morning). It just sicks there at 12.38V period.

However, there are times where I can see the voltage literaly ever so slowly dropping.
I mean slowly soooooo slowly (like an 1HR period it will go from 12.38v to 12v).

Problems I've had:
The back window defroster is messed. The circuit board shorted out to shiat, burnt black
so I pulled it all out. Cut the wires (capped them).

Also the body molding has a light for when you turn (that shorted out, so cut the wire and
caped that).

The issue is that only some days the battery will drain, other days nothing.

When I park the car and go shopping or in house. I remember to always turn off things like
stereo, the fans, cruise control switch to off.

Then lock the car with remote.

Any suggestions what to do to check for what's causing power drain?

I have read people saying the security on car not letting it start can be a sign
of the battery draw caused by the security circuitry shot.

When I have juice in the battery the car runs fine. Drives fine. Locks/unlocks fine.

Suggestions?

More about : unknown circuit causing battery drain sporatic

February 8, 2014 7:56:26 PM

first off when you put your volt meter on your battery as you are your just taking and open circuit voltage which is a good indication on the state of charge and 12.3 is not bad 12.6 is perfect because an automotive battery is mad of 6 cells that are 2.1 volts each, that being said what you need to do is a parasitic draw test which is when you take an amp meter and hook it in series ( unhook the positive battery cable and put one lead from the cable end to the meter and the other meter to battery positive post)

First park your car someone where you wont have to move it and can monitor it periodically for an extended period of time 2-4 hours usually, then pop the hood and make sure everything is off and all doors are shut this is important, then hook your meter up as i had described above but make sure that its an amp meter on the amp meter setting and be careful most meter have a max capacity of about 10 amps which isn't much and you could easily damage your tool by activating something like the power window or starter. Once its hooked up you should be getting a reading of above 0 you will need to wait about an hour before you get a base reading because the modals in your car need time to "go to sleep" so leave it sit for an hour and recheck when you do it should be less than .035 amps but anything less than .05 amps is okay if its higher than that let hope on and let me know what your readings are different components draw different amounts and i can usually get a good sense of the culprit from the numbers

just an after thought if you have one of those monitoring devices the insurance company's send out plugged in to your OBD2 i would remove that first as a mechanic I've seen several of those cause a similar problem
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February 11, 2014 8:13:38 AM

where u live some stores offer alternators and battery check free of charge.
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February 14, 2014 6:30:01 AM

I pulled every fuse, disconnected the alternator, pulled the stock gm stereo, unplugged rear window defroster.

It was the rear air ride level control ride module. Seems to cause a 500milliamp draw. crazy!
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February 14, 2014 10:58:25 AM

hope the advice helped and I believe that you can get standard struts without the air ride part to replace those so you won't have to worry about it
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February 19, 2014 8:47:01 PM

wow
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February 20, 2014 6:35:38 PM

Wow...?
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March 1, 2014 11:48:12 AM

I just left it. Car is riding on the air bags right now. I may change it but ah well. The car has 400 k mileage and things seem to be fine thus far.
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March 1, 2014 12:59:04 PM

Yeah with 400k miles on that car it's best to not put much money in to it now. Good job figuring it out. Electrical issues can be a real pain to figure out sometimes.
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March 1, 2014 1:01:51 PM

I must have grown some gray hairs figuring it out. I ended up getting to a mechanic to have him log into All data dyi website and do a search. I ended up finding out the problem.

I pulled all the fuses and did an amp test, which didn't help exactly pin point out the issue. I have to many minor issues (like rear defroster is shot, heating elements in the door mirrors are shot, tape stuck in deck).

With the 400k on the car and it being a boat/gas gusler i said screw it.
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