Battery Drain

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Sep 5, 2007 | 12:09 PM

OlpA77

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Battery Drain

I just bought a 1987 Bronco II with a 2.9L. When I picked it up everything worked great. I let it sit over night and the battery was drained. I charged the battery up and every thing worked great. Let it sit over night again and every thing was dead again. I went to Autozone and bought a new battery. Same thing is going on with the new battery. I noticed when I am charging the battery with the battery charger (on low 2amps) the alternator gets really hot to the touch. When I put the new battery in the alternator got hot too, the engine was off all day so no chance it was heat off the engine. The wires to the alternator stay cool. My handheld amp gauge shows the alternator is charging okay. Do I have a short in the alternator thats causing the battery to go dead or is there some kind of diode/solenoid causing this?

Thanks,
Aaron

Sep 5, 2007 | 03:34 PM

87 XLT

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From: SoCal

Yep, looks like the diodes in the alternator are shorted out. Throw a new alternator on it & you should be good to go.

Congrats on the new ride.

Sep 5, 2007 | 03:36 PM

87 XLT

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From: SoCal

OOPS double post

Last edited by 87 XLT; Sep 5, 2007 at 03:47 PM.

Sep 6, 2007 | 05:13 PM

SShank42

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From: SOUTHEAST OHIO

Take the alternator and have it checked. Mine did similiar and it was the rectifier that was bad.

Sep 8, 2007 | 01:41 AM

rebocardo

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From: Atlanta GA

> I noticed when I am charging the battery with the battery charger
> (on low 2amps) the alternator gets really hot to the touch.

This is one reason you should not charge a battery with the cables connected.

Though this is the first time I have heard of an alternator getting this hot, I would be willing to bet the zener diode is cooked. Maybe from the charging.

Plus, I would check for a short with a test lamp between the negative cable and battery. If it lights up, try disconnecting the alt. harness. If it is still there, start checking the fusible links.