Battery losing charge?? Faulty alternator?? Help.

[Erick]

Alright so here's the deal. I'm constantly draining my battery. I tested the battery and both the ones I have (I have one from my parts car) are fine.... yet they are still getting drained.

So alternator right? Well.... when the car is on it wont turn off. Just now I tried to start the car and the battery was drained. I jumped the car and the car started right up, stayed on, and I drove home on like that. I can completely disconnect the battery and it still stays on.

Something is draining my batteries but I dont know what. I have not done any recent wiring that changed this condition so I'm really at a standstill. Someone suggested that even when off, the alternator is taking a charge from the battery (I tested the alternator at Advance Auto Parts and it was fine).

So I dunno, ideas, thoughts?

Thanks,
Erick

[jmarch]

I don't fully understand what you mean by "I can disconnect the battery and it still stays on."

However, I'd start with checking the current draw at the battery. Disconnect the ground cable and place a multimeter between it and the battery. Then go to your fuse box and start pulling fuses one at a time. After each pull, check the draw. When you pull a fuse which significantly reduces the draw, you've found your problem. Then take a look at your owner's manual to determine which components work off that fuse. Generally it's something like a glovebox or trunk light which doesn't turn off (usually due to a bad pin switch).

Good luck,
Joe

Begin by doing a spot check around the car. Generally

[92 mtechnic cabrio]

When he says that when he disconnects the battery and the car stays on, it means that he's trying to say that the alternator is doing its job. This is not a good idea, by the way, Erick, for our cars, owner's manual states it is bad for the ECU and whatever.

Your batteries are probably too old to hold a charge.

Erick, replace your battery, I had the same symptoms as you and it turned out to be the battery because it was:

A) too old
B) rough ride
C) rough life
D) multiple complete discharges

The only thing to prove against this is to use the same battery in a car without the drain problem.

[AdamF 88iS]

I don't fully understand what you mean by "I can disconnect the battery and it still stays on."

However, I'd start with checking the current draw at the battery. Disconnect the ground cable and place a multimeter between it and the battery. Then go to your fuse box and start pulling fuses one at a time. After each pull, check the draw. When you pull a fuse which significantly reduces the draw, you've found your problem. Then take a look at your owner's manual to determine which components work off that fuse. Generally it's something like a glovebox or trunk light which doesn't turn off (usually due to a bad pin switch).

Good luck,
Joe

Begin by doing a spot check around the car. Generally

Whoever this guy is, he's right.

[jlevie]

Well.... when the car is on it wont turn off.

I'm wondering if the OP means that when he turns the key off that the car continues to run. If that's the case it would be no surprise that the battery drains when the car sits and would tend to point to a problem with the ignition switch, wiring, main relay, etc.

[Erick]

Thanks guys, I'll start looking into it. I'm still learning the whole electrical aspect of the car... I mean, I wired my euro ellips, but when it comes to checking voltage/resistance/etc or even knowing exactly what all that means, I'm at a loss.

jlevie, I meant that when I disconnect the battery (key still on) the car continued to run. When the key turns off, the car shuts off normally. That's not a problem there.

[f u z z]

I am having the same problem, and i have have an optima yellow top. sooo it really sucks.

[porsche gt1]

I don't fully understand what you mean by "I can disconnect the battery and it still stays on."

However, I'd start with checking the current draw at the battery. Disconnect the ground cable and place a multimeter between it and the battery. Then go to your fuse box and start pulling fuses one at a time. After each pull, check the draw. When you pull a fuse which significantly reduces the draw, you've found your problem. Then take a look at your owner's manual to determine which components work off that fuse. Generally it's something like a glovebox or trunk light which doesn't turn off (usually due to a bad pin switch).

Good luck,
Joe

Begin by doing a spot check around the car. Generally

you can do the same with a 12v test light. When you do this procedure make sure you press the button on the truck so the light does not go on, otherwise you will show a draw from the light.

[Erick]

I am having the same problem, and i have have an optima yellow top. sooo it really sucks.

Definetly the fact we rock 16x9s. Batteries are wack.... they hatin' on us. :)

[jmarch]

Whoever this guy is, he's right.

I'm just some hack mechanic who likes E30s........

[92 mtechnic cabrio]

Definetly the fact we rock 16x9s. Batteries are wack.... they hatin' on us. :)

I'm starting to have a battery problem too, and I have an optima red top

must be the 16x9s

(audio is starting to get all wacky on me)

[Brew]

\ meant that when I disconnect the battery (key still on) the car continued to run. When the key turns off, the car shuts off normally. That's not a problem there.

Eek, don't do that again.

You have a "key-off" draw as the other guy mentioned. You should have less than 40mA current draw with the key off and all interior/exterior lights off.
If you allow the battery to drain too many times, you will likely have to replace it.

[Dave]

Eek, don't do that again.

You have a "key-off" draw as the other guy mentioned. You should have less than 40mA current draw with the key off and all interior/exterior lights off.
If you allow the battery to drain too many times, you will likely have to replace it.

QFT. I love Autozone's warranty on batteries - I have gotten like 7 of them for the price of one as a result of low draw on 2 of my 3 e30s.

They sit a long time without use, and I have never bothered to trace the problem. Lazy me.

I am committed to finding the draw on the current one. Sometime. Really . . .

[Erick]

Guess I gotta get around doing that.

[Dave]

Yeah, I never bothered, because, well, 1) I am lazy about somethings, and 2) whenever I get in the habit of driving it at least once a week, it never discharges enough to be a problem.