Battery drained inself??? How do I find out what is pulling the electricty?

68converted · Mar 6, 2009

I worked on the car a week ago. I had been taking the positive lead off during the week as I have only been able to work on wraping up the wiring loom on the weekends. I forgot it last weekend and when I came back today. The battery was dead, and I mean really dead. I brought it to Wal-Mart to get a replacement as I could not even get it to jump. They said it was 100% dead.

So dead in fact they just gave me a new one...

How can I find out what is draining the battery??

95Vert383AOD · Mar 7, 2009

I had the same issue. Turned out that it was the Alternator. It would charge fine and when i shut the car off the Alternator was draining power. If you have the 3G Alternator i hear this happens when the Alternator is going. Other than that you can check the typical stuff like Glove box, trunk etc. not turning off.

zookeeper · Mar 7, 2009

Typically, I remove the negative lead, then lightly touch it to the post. If you see a healthy spark jump just as you make contact, you know there's a short somewhere. Then, one at a time, remove the fuses, and re-do the spark test after each fuse you remove, once it quits sparking, you know you've at least found the offending circuit. Also, if it's draining the battery that quickly, you know it's something with a fairly large draw. If it were me, I'd start by removing the taillight/dashlight fuse, since they are often broken or worn where the taillight harness passes into the trunk. Don't forget to check the area you last worked in as well, you never know when you accidently bared a wire or pinched it against something. Good luck!

68converted · Mar 7, 2009

Thanks for the tips. I will check using your suggestions on the Alt. and the fuses. Thanks

68converted · Mar 8, 2009

No luck. When connecting the positive cable before I started the process, I didn't have one big spark; more like a bunch of very tiny one's. I pulled the Alternator connections first, no change. Then leaving that connection off, I pulled each fuse successively and there was no change. Still getting the little sparks.

I checked the battery on my Explorer, and when pulling the positive cable and putting it back on, got the same little sparks, in fact every car I have ever owned has had a little spark when connecting positive???

Any other ideas?

Grabber70Mach · Mar 8, 2009

I think zookeeper said to disconnect the negative wire, not really sure if it makes a difference though.

Tim65GT · Mar 8, 2009

68converted:

Any other ideas?

Use a Brake light bulb and a socket with some short lengths of wire and some small clips will help. Put it in-line with one of the battery cables. If it lights up, there is something drawing too much current (more than 3 Amps). If you disconnect something and the light goes out, then you have found the bad circuit.

This also works by pulling a fuse and putting the wires of the test lamp across the fuse holder terminals.

View attachment 267272

BarnStang · Mar 8, 2009

THe newer cars will pull a small amount of current for the computer. Not a good comparison. Have you pulled the connection to the voltage regulater? If you have a 3G then that won't matter-should be disconnected anyway. You don't have a door haning open whenchecking the draw at the battery term do you? (I've done that...)
It would be better to have a meter to check the current flow in series with the battery cable, but you can resolve it without one.
If the alt, voltage reg, are disconnected, and all the fuses are out, and the doors are closed, you need to try more drastic measures. Post back again and let us know you've checked with the volt reg pulled or if you have a 3G.

68converted · Mar 8, 2009

BarnStang said:
THe newer cars will pull a small amount of current for the computer. Not a good comparison. Have you pulled the connection to the voltage regulater? If you have a 3G then that won't matter-should be disconnected anyway. You don't have a door haning open whenchecking the draw at the battery term do you? (I've done that...)
It would be better to have a meter to check the current flow in series with the battery cable, but you can resolve it without one.
If the alt, voltage reg, are disconnected, and all the fuses are out, and the doors are closed, you need to try more drastic measures. Post back again and let us know you've checked with the volt reg pulled or if you have a 3G.

Yup, it's a 3G. with all the old voltage regulator stuff pulled out. I didn't have time to put a meter in series with each fuse; but am I correct in saying that there should be zero voltage unless something is in use... i.e. interior lights, dash lights, blower motor or something?

I will have some time this evening to do some more testing; and I really want to find out what is causing the trouble. Kind of scarry if you ask me. I would hate to burn down the storage garage.. Yikes.

zookeeper · Mar 8, 2009

If all checks out OK, and it doesn't go dead overnite, it may have just been a bad battery last time. It doesn't sound like you have a killer draw on it anywhere, so leave it hooked up and see if all is well.

BarnStang · Mar 8, 2009

The fastest way is to run the lamp test Tim65GT posted up. If you have no light, than it was probably a bad battery as suggested. It now dawns on me that it's EFI. Sorry. So you will have a small draw. Not sure a week of not running an EFI car with a new battery would be enough to kill it. See if you get a light, should get something for the computer. But not enough to kill the battery. You may still need to get a meter and see exactly how much current it's drawing. You may want to consider a battery tender. I have a small one for my garden tractor. In January, I switch it to the Harley. In March they both start flawlessly. Even a small one would be enough to keep the battery up even with EFI.

68converted · Mar 9, 2009

BarnStang said:
The fastest way is to run the lamp test Tim65GT posted up. If you have no light, than it was probably a bad battery as suggested. It now dawns on me that it's EFI. Sorry. So you will have a small draw. Not sure a week of not running an EFI car with a new battery would be enough to kill it. See if you get a light, should get something for the computer. But not enough to kill the battery. You may still need to get a meter and see exactly how much current it's drawing. You may want to consider a battery tender. I have a small one for my garden tractor. In January, I switch it to the Harley. In March they both start flawlessly. Even a small one would be enough to keep the battery up even with EFI.

Well, on the Explorer I have now. It sat in a garage unused for a solid year. When I dusted it off and turned the key it started right up, and that battery was the original from 1999. I don't think the computer uses much. I should be able to run some tests tomorrow night. I read up on the meter I have an will do a current draw test. With those parameters, I can narrow down quite a bit, then I think I will just need to systematically work my way thru the system??

Battery drained inself??? How do I find out what is pulling the electricty?

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