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i have a 96 explorer, i have a battery drainage problem i cant figure out .i have pulled bulbs from glove compartment , under hood, removed trailerr wiring, and have replaced battery and alternater, i even pulled my cig. lighter out. still battery is dead in 6 hours. If i pull my pos. battery termnal things are ok. anyone ever have this problem or any futher suggestions would be great.
Welcome, You said if you pull pos. battery cable things are fine. You might have a bad cable. Trace it from the battery back you might have a bad spot or it is corroded somewheres in the cable itself.
Disconnect the battery neg cable and attach a voltmeter between the cable and the negative post. If you have a short it will read +/- 12volts.
If so, start pulling fuses and have someone watch the meter as you do it. When the meter goes to zero, that is the circuit with the short. If that doesn't locate it, disconnect your alternator. If it goes away, change the alternator.
It's gonna show 12 Volts anyway after you pull the cable. There's always a little bit of current pulling for the radio and/or the PCM and possibly some other options like security system etc. You'll really need to check the amp load after you pull a cable. Most multimeters will only go to 10 amps, a few will go to 20 and a very few will go higher. If your battery is dying in 6 hours making the assumption that it has around 100 amp-hr supply and assuming your definition of dying means 80% drain, it will be pulling an amp load of around 13 1/3 amps. Obviously there are a lot of assupmtions in that calculation, but it's probably in the ballpark. Larger amp-hr battery or larger %drain in the same time frame will increase the amps, longer time will decrease the amps. Normal loads for the PCM, Radio, Security, etc. should be well below 1 amp. If you can find a meter that measures the load it's under, you can disable circuits by pulling fuses, disconnecting the alternator, etc. until you find the one that drops the load.
You should be able to turn off security. Radio memory shouldn't pull 12v.
You could use a 12v test light in place of the meter. If there is a tiny current draw, it will only be a very dim light. But whatever your problem is will cause a bright light if it drains the battery that fast.
Be sure to close the doors and take the underhood light bulb out when you do your testing.
Difference between a light and a votage meter is the light puts a load on the circuit and a votage meter does not. Thus with the light you are observing the amp load up to the wattage of the light, then the resistance will clamp it off. Any circuit that is connected and has no load will show the open potential for the circuit. With a 12V battery the open potential is 12 volts.
No, with the light in series with the negative cable, it imposes no draw. It does not make a complete circuit by itself. It will only be illuminated by the amount of amperage through a direct load, which is the whole point of this common test. If all circuits are off, and there is no short, there will be no voltage applied to the test light bulb.
Thanks for all the suggestions will try most of them. surprised by the responce,i got ,thanks again .
Sorry we got sidetracked there. The light thing works fine, it's an industry standard test method. So do the other ways, it just depends on what equipment you have at hand.
thank you, with your help, i have found my problem, i tried the neg. battery cable to neg. post suggestion , and after all the pulling of fuses, it turned out to be my stereo,i got a short in the wiring going to the radio .so thanks again .i owe you guys.