Battery or Alternator?

[Fassi]

Hi,

I'm having an electrical problem that has left my car disabled on the side of a DC street. After a day of normal driving, my car would not start. I'm able to jump start the car, but it dies after a couple minutes or less. During that period, the lights get progressively dimmer until everything goes dead. The alternator/battery light had come on intermittently throughout the day, and did not seem to be directly affected by the engine speed. Incidentally, the last couple times I jump started the car, the battery light did not come on while the engine was running. The alternator was replaced in 2001 with a refurbished unit from Vertex Auto.

Is the problem likely to be the battery or the alternator? I would appreciate any advice or assitance. .Should I just buy a new battery and put it in on the side of the road?

Thanks.

[azasadny]

Alternator!

[wilke3169]

SOunds like the alternator is bad but, You could install a charged battery to get home.

[falcon]

Check the voltage on your battery with a voltmeter if its less than 12-12.5 Volts then its not charging. Either the battery does not hold a charge or your alternator is not charging it. I had a similiar problem in which I barely was able to measure the voltage when the car was running because the car would die after 30 seconds of idling rough. Due to the collective brain power of this board, it was recommended that I start with a charged battery, then determine if the alternator and/or regulator is bad.

You did not mention anything about replacement of the Regulator at the time of the refurb of the alternator. Mine had worn carbide contacts which contact the rings within the alternator. Check out topic "3.2 low idle" for reference.

[Fassi]

Thanks for the replies. I was under the impression that if it were the alternator that the light would most likely go out under higher revs since--based on what I've read--the alternator/regulator unit tends to fail gradually over some time rather than all of a suddent. That probably doesn't make much sense under the circumstances, but I was really hoping it would be as simple as a battery swap. Like I said, I just replaced the alternator/regulator unit in Dec 2001, and I can't believe I'm going through this ***** again. If anyone in DC can help me out, please let me know. In the meantime, any other suggestions would be great.