strange electrical problem. grr

[djtodd]

So, I'm driving along night before last, and notice my window is rolling up very slowly. At this same time, I notice my lights are pretty dim. Hmm, rev the engine and lights get brighter, but window still pretty slow. I don't have a system/amp in my car that pulls much juice. Go into a restaraunt to eat, come out and my car won't start. Tries to turn over once or twice, but it's like the battery is dead, which it is.

So I get a jump, let it sit and charge for about half an hour, turn it off. Try to start it again and no-go. Same thing. I take the bettery to have it tested and it's good. Holds a charge fine. Although it was completely dead.

So I check the alternator, it's putting out between 13.5 and 13.9 volts at various rpm's including idle.

I replaced the large positive wire from alternator to battery, checked all grounds, connections etc. Nothing is out of the ordinary.

I have since fully charged the battery out of the car, and have been driving it today. But I'm afraid it's draining the battery again. I'm hoping it's the alternator just not putting out enough current to keep the battery charged, but the strange thing is, the car ran fine with the dead battery.

Anyone have any ideas of other things to check?

[GodDrivesA240sx]

So, I'm driving along night before last, and notice my window is rolling up very slowly. At this same time, I notice my lights are pretty dim. Hmm, rev the engine and lights get brighter, but window still pretty slow. I don't have a system/amp in my car that pulls much juice. Go into a restaraunt to eat, come out and my car won't start. Tries to turn over once or twice, but it's like the battery is dead, which it is.

So I get a jump, let it sit and charge for about half an hour, turn it off. Try to start it again and no-go. Same thing. I take the bettery to have it tested and it's good. Holds a charge fine. Although it was completely dead.

So I check the alternator, it's putting out between 13.5 and 13.9 volts at various rpm's including idle.

I replaced the large positive wire from alternator to battery, checked all grounds, connections etc. Nothing is out of the ordinary.

I have since fully charged the battery out of the car, and have been driving it today. But I'm afraid it's draining the battery again. I'm hoping it's the alternator just not putting out enough current to keep the battery charged, but the strange thing is, the car ran fine with the dead battery.

Anyone have any ideas of other things to check?

Sounds like your alt is shorted out. You may have also burned it up trying to recharge a dead battery off of it. Alternators today are designed to maintain a charge, not to recharge a battery There's a trick you can do with a circuit light. I don't remember how it's done but it involves removing the alt fuse and checking to see if it's got power, I guess if it's got 12v charge going to it if the switch is off then it's shorted.

[djtodd]

I didn't use the alternator the charge the battery. It was done out of the car, with a charger.

[GodDrivesA240sx]

So I get a jump, let it sit and charge for about half an hour, turn it off. Try to start it again and no-go. Same thing. I take the bettery to have it tested and it's good. Holds a charge fine. Although it was completely dead.

My bad I must have taken that wrong Either way it sounds like a short in the alternator.

[blackbeauty240]

if when you rev your engine the lights get brighter then the alternator is putting out. it sounds like the voltage regulator that is built in to the alternator so yes i would test the alternator and replace as needed