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Discussion Starter #1
Battery drains overnight. How to determine where the drain is coming from. Best way to test and locate the drain?
 

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I would pull fuses one at a time and place a DC ammeter across the two fuse contacts. You will measure the current through that fuse. It should be zero or very close to it.

Don
 

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First remove the battery or disconnect it completely and charge it and leave it sit overnight. It may have a bad cell and be discharging itself with no outside help. But then definitely do the fuse test.
 

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Remove a cable from battery post and insert a test light, I.e., 1156, any single filament bulb, between disconnected cable and post.
Current drawn will be limited due to bulb filament.
The dimmer the bulb, the less current demanded.
Lights are better to see than a gauge.
If no light, then poorly charged battery or bad battery, as suggested.
 

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Discussion Starter #5
Would a test light work as well? Does it matter which post? Could the alternator have anything to do with it? The battery has been disconnected on a battery maintainer most of its life due to the discharging issue . . . time to fix it!!
 

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The alternator could be part of the problem if it isn't fully charging the battery. You would need a volt meter to test the output of the alternator, or take it to autozone or another autoparts store and they will test it for free. Also the battery maintainer help extend the life of the battery, but do not ensure that it is working properly.
 

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Would a test light work as well? Does it matter which post? Could the alternator have anything to do with it? The battery has been disconnected on a battery maintainer most of its life due to the discharging issue . . . time to fix it!!
A test light "may" work but I have no experience using one to check for current draws because I bought a meter years ago to know more of what I am dealing with. We could assume that with a bright illumination of a test light bulb we have a bigger draw than if it was not as bright but it doesn't give us a number. Someone may have figured out a way to get an idea when a particular bulb such as an 1156 or 1157 bulb is used that a decent brightness the draw is 5A (and this is just a random number I'm throwing out) but at a barely seen illumination with no other ambient light in the room this now means you have 0.01A draw.

I'm guessing you have friends that may have a meter you could borrow or have them come by to show you how one works and that would be ideal so maybe ask around.

As far as troubleshooting, removing the fuses one at a time under the dash or even all of them may still leave the car with a battery drain and one could have issues with the alternator, the voltage regulator, and/or even the horn/key buzzer relay.

While you have been having an issue for a while, I would go ahead with using a test light but ideally get a meter. Using the test light can be used on either post to cable end. Be aware too that if the test light is using LED's then this brings in different ways it can or cannot be hooked up and/or used.

JIm
 

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True, an ammeter is best, but the tech has to make an adjustment, then go look at meter and repeat.
With alight, and long leads to drvr side, makes the situation alittle easier.
As I suggested, the bulb filament limits the amount of current drawn as shown by the brilliance of the bulb.
A test light can be used, but not an LED.
Hook the light between the disconnected cable and post from originally attached and the bulb does not matter the direction it is connected.
It works both ways.
 

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A bad diode in the alternator can also cause a battery to drain overnight. Pull the plug in connector off the alternator while having the test light between the battery and battery cable will help confirm it.
 

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Discussion Starter #12
Thanks guys, I will get at it tomorrow. I have an amp meter and a coupla test lights to check it out. Will let you all know.
 
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