Battery problem or Alternator/Regulator

[Navajo]

I have a '91 Navajo, and when the car is idling with some accessories running(A/C, headlights), the voltage drops considerably(from 14-14.5V to around 12.5) and the headlights dim a lot. When i rev the engine, the voltage comes back up though. I was under the impression that the voltage should remain relatively constant. Does this sound like a problem with the battery, or one with the alternator or regulator? The alternator is only about 6 mos. old, so i wouldnt think it would be that. Oh well, if it happens to be the alt, i guess i'll just go ahead and go for a 200A replacement, for the upcoming stereo.

 

[Frisckey1]

Trick

My husband taught me...if you think its your battery, turn off engine but place ignition in accessories position. Then turn on some of your accesories...if your battery drops down low real quick, its probably your battery. Same problem I am having right now. Tempting fate...everyday it starts is I am 1 up on fate! lol Actually, I have just been tight with the money and am guessing it will take it not starting to make me replace it. I would say 6 years out of the original battery is good, no?

 

[IAMCDN]

Just because the alt is only 6mo old, doesn't mean it isn't good. I have had a "reconditioned" alternator be garbage right out of the box, another last 3 months, and others last a long time. Your symptoms sound to me exactly like a bad alternator.

Take your vehicle in to a good parts store(I think someone in another thread said Pep Boys or Auto Zone in the US, I think the names are correct, we don't have these in Canada) and they will test the alt for you and it should be free or almost free.

 

[ChrisHeapy]

Could be the alternator, but in my experience these either work OK or they don't work at all. Might be the voltage regulator, or might be the battery. I just hate getting a flat battery so always replace with a new one after 3 years anyway.