1994 Sentra Alternator Doesn't Charge


Old 10-20-08, 06:52 PM
jayedmo's Avatar
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Location: Medford, NY
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1994 Sentra Alternator Doesn't Charge

Got a '94 Sentra LE..about a month ago, the battery light and the emergency light would intermittently come on and off. About a week after that, the car began to buck while I was driving..almost as if I had no power.

I took it to a friend of mine who's a mechanic and he bench tested the alternator. It was dead, so I replaced it.

Everything is hunky dory for about a month and once again the lights come on and a week later, the car starts bucking again.

I borrowed a voltmeter and tested the voltage of the battery and the alternator. The alternator was reading 10 volts and the battery was only reading 8 volts.

I don't know where to begin to look, but some of the info that I've found online suggest that the alternator I bought was bad and/or I have a loose connection..

Sorry for the long read...any suggestions? Any help would be appreciated.
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Old 10-21-08, 07:12 AM
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Stuff happens. It does sound like the alternator died. It can happen and seems to be more frequent with rebuilt units. I would think that it would still be under warranty. Have your friend check it and then, if bad, take it back to the store for a replacement.
Old 10-21-08, 08:12 AM
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Had a very similar thing happen to an older Honda I had. Turned out the main lead from the alternator to the battery was broken in the run. Covered up by the tape and whatever. It would read good with a meter when parked with engine running, but when driving it would not make contact.
This would cause the voltage regulator to call for juice to charge the battery, but since it had nowhere to go, it would overheat and burnout the diodes in the alternator.

Was on my third alternator when I finally broke down and took it somewhere. They found it in 30 min or less. $25 and a splice in the line and I was good to go.

Try visually and electrically tracing the line from the hot side of the alternantor to the battery. Also make sure you have solid clean grounds for the battery to the engine.

And, of course it could just be a bad alternator, as goldstar mentioned.
Old 10-29-08, 07:41 AM
Join Date: Apr 2005
Posts: 194
I'm guessing that you used a replacement alternator from Autozone, Pep Boys, Advance Auto, or some similiar place. Get a good one from NAPA instead.

Last edited by the_tow_guy; 10-30-08 at 04:59 AM. Reason: Softened the comment a bit.
Old 10-29-08, 02:56 PM
Join Date: Jan 2002
Location: Chicago
Posts: 1,915
It's also very likely that the batter is defective, even a discharged battery should still read ~12V with just a multimeter load on it. 8V would imply 2 of the cells are dead.

A defective battery is the quickest way to damage an alternator as it will work at full load all the time.

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