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Battery Drain ---> how to track?

Something is putting a constant drain on my battery. How do I track it down?
With the multi-meter on the batt while the car is running, it stays at around 13.5 but does NOT increase as I rev it like my old Camaro did. Does that mean the Alternator is not charging?
I can watch the voltage go down quickly when the car is NOT running but the voltage does NOT go down while it is running so that kinda tells me the alternator is doing something right?

Old 11-09-2005, 03:25 PM
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The voltage regulator should keep it around 13.5......

So your alternator seems fine...

Either your battery can't hold a charge or you have a drain...

Well the quick way stick the volt meter where you can see the readings.... start pulling fuses until it stops dropping.



I would check for amps which is a little more accurate but the previous way is quick and painless.
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Old 11-09-2005, 03:45 PM
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Well the battery is only a couple months old.
I thought of the pulling fuses method, I guess I'll try that
Old 11-09-2005, 04:02 PM
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Car off. Disconnect one terminal of your battery and connect your meter in series (one lead on the battery terminal one lead on the cable you disconnected). Be sure your meter is set-up to read amps or milliamps (you may have to plug a test lead into a different jack on your meter depending on the meter). Note the value (50mA~60mA, is normal with everything off, I think, and don't worry about positive or negative current for this test - ignore the "-" sign if you've connected things so that the current reads negative). Then pull fuses one at a time until one of them drops the current significantly. That will be your problem circuit. Don't try to start the car with the meter in there or you'll blow the fuse in your meter.
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Old 11-09-2005, 04:16 PM
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thanks gtroth
Old 11-10-2005, 02:15 AM
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Hmmm...mine reads 13.6 when running, but if I drive the car for a while, it can drop to 12.
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Old 11-10-2005, 05:31 AM
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Voltage tells very little except if low then check the charging system or dead cell on the battery. The only draw in the ~20-50 ma or .05 in the amp range is the radio memory. First test do with all lights off. This means doors closed and the light under the hood off. Make sure the interior light are off before the fuse tests.
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Old 11-10-2005, 10:42 AM
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FWIW - I kept waking to a dead battery. Ends up my cooling fan would not shut off due to a bad relay.
Old 11-10-2005, 10:43 AM
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Quote:
Originally posted by Ross T
FWIW - I kept waking to a dead battery. Ends up my cooling fan would not shut off due to a bad relay.
I just put in a new relay last month but I will check it, I could have gotten a bad one
Old 11-10-2005, 10:47 AM
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pull fuses one by one untill it stops... if not, the problem is before the fuse block...
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Old 11-10-2005, 04:56 PM
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Quote:
Originally posted by hpaulb
Voltage tells very little except if low then check the charging system or dead cell on the battery. The only draw in the ~20-50 ma or .05 in the amp range is the radio memory. First test do with all lights off. This means doors closed and the light under the hood off. Make sure the interior light are off before the fuse tests.
Clock will also probably draw a few ma. Start initial fault finding with multimeter on higher A setting in case there is something drawing more than ma (depends on your multimeter and safety fuse what you will get away with before blowing it)
Old 11-11-2005, 01:27 AM
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Few weeks ago I got the same problem .. it was my snoozer sit belt realy .. stuck .. ! wel now, I drive without this, but plan to buy it and replace.
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Old 11-11-2005, 06:31 AM
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I have had a similar problem. My year old battery would drain if I did not drive the car for a week or so. My engine would cut out and then I was able to restart within a few seconds. I resoldered all the DME relay connections and I cleaned and checked every connector from the fuse box forward. I found I was losing 1 volt between the negative terminal and the earth strap to the body. I replaced the earth strap and situations improved. The DME seemed to reset with a low voltage.

However the battery would still drain after a week of standing. I checked the alternator charge and was getting 14V plus when running. I replaced the battery and the problem still occured. I checked the current draw through each fuse and discovered the following: If you turn off the interior light (middle position) this activates a safety relay for the electric windows and with the door closed and engine off the windows still work. This circuit draws 0.15 Amps continuously. This doesn't sound like a lot but adds up over a week.

Logic says that if there is a battery draw, then it would be wise to switch off the interior light but this actually makes the situation worse.

My Battery drain is no more with the interior light switched to come on when the door is open.

Old 11-11-2005, 12:44 PM
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