I just replaced the alternator. The car dies if I disconnect the battery. I'm getting 12.96v from the post on the alternator to a ground and I cleaned the battery connections.

My question is what could be keeping the alternator from charging the battery?

 

Why would u disconnect the batter while the car is runnin? Do u mean ur jumping it and it dies wen u disconnect the jumper cables?

 

There is a heavy white wire that runs from alternator to the fuse box... and that runs through a fuse and to the battery.

Check your grounds and clean them up.
Inspect your wires especially where they open up to a connector or lug.
Water sometimes gets in through there and corrodes the wire.

Your alt should be putting out a full 14v so maybe it's a defective alternator (they aren't always perfect even though they are new). Bad wiring or ground could cause this.

 

faulty alternator
now that is change that i can believe in...!!!

 

you should be able to run the vehical on just the alt. no real need for a battery other than starting

 

Right, that's what I tried and it would just die (alternator was basically disconected from the car).

 

I'm having bit of trouble finding where the white wire leads to.
I think it runs to the fuse block on the shock tower but I'm not positive.

 

if its wiried up as it should be it could just be bunk

 

lemme gues.. you got the alternator from autozone?

 

OK now your scaring me

 

yup u got a bunk one!!!!

 

That's where it goes.
If you can test for output right at the alternator you should see 14V.
Guessing you will see that 12.6V again... and it's a bad alternator.

 

OK,
I disconnected the white wire from the alternator and started it up.
I put the positive test lead on the post the white wire goes on and the black lead on the frame.

I only got 1.47v from it.
I'm guessing that it was back feeding from the battery before?

I'm sure this is getting very technical but does the green plug on the back of the alternator tell it to "turn on"? I just don't want to pull it back out just to find out it's something else.

 

return the alternator to autozone if it does not produce 14.5V when operating normally. its very common to get a bad one from autozone. youre the second person in two days to come here wondering about a "new" alternator gone bad. it happens regularly with autozone alts.

 

grounds good on the valvecover?

 

Wait, what?! That can interfere with having signal to the alternator?! 😬