Alternator going bad?

[Gremlinsteve]

Ok

13.8 ac off at stud on alt
12.2 with ac on

12.3 volts with plug unplugged from alt at idle ac on

12.3 volts measured at red wire on plug

12.2 volts at the positive terminal on battery at idle
Ac on or off

I know the alternator is regulating. It drops the engine rpm with it plugged in

 

[Gremlinsteve]

Pics

 

[Jube455]

Could he not disconnect the battery with the car running, and if the engine dies the alternator is pooped?

 

[Gremlinsteve]

It's runs still

 

[Gremlinsteve]

It's as if the alternator is not charging properly though

I'm going to remove it and return this thing

Replace with another

 

[fleming442]

Could he not disconnect the battery with the car running, and if the engine dies the alternator is pooped?

That's dangerous to do these days, especially if there are any computers involved. I think it's a weak alternator, and I'd take it back. Or, buy a new one, and return it as not needed after the swap. FWIW, I went through 3 Mexican remans DOA from Carquest, and finally got a Chinese that worked. 4th times a charm....?

 

[pontiacgp]

how did you determine the alternator you had on the car was bad before you bought another one

 

[fleming442]

Me? 12.8-13.4 at rpm on the charge stud and a weak 'alt' idiot light on......

 

[Gremlinsteve]

It's as if the alternator is not charging properly though

I'm going to remove it and return this thing

Replace with another

 

[axisg]

I would be looking at the battery. 13.8 is OK( ish) at the lug on the back of the alternator. Bad / weak cell in the battery can be pulling the voltage down