New Alternator acts weird, and barely charges battery.

[Ribbedroof]

Sounds like you need to check the brown wire for continuity and resistance.

In your application, the brown wire tells the alternator that there is a load, and that the alt needs to supply current. If the wire is not capable of relaying that to the alternator, you are going to have charging issues.

I would use a DVOM to check between the alternator plug and ignition switch, and have a helper move the harness while testing. I think there are problems in that wire...perhaps it has broken strands in it that cannot handle the current load, or are intermittently losing contact.

 

[MalibuHacon]

Thank you, Ribbedroof. I will perform the tests, and try to clean all the ground connections. What does this ignition switch/harness etc. look like?
and DVOM is the same as a multimeter, right?

 

[foxtrot]

DVOM = Digital volt-ohm-meter

Same as multimeter in function

 

[foxtrot]

I had similar symptoms with my Regal that I debugged a few years ago. In my case, it turned out to be a bad ground between battery and the block. I observed a small voltage drop between the battery and the block. After fixing this issue, the charging system worked just fine.

 

[MalibuHacon]

(Okay, so with the help of one of the guys who works at the club, who is a mechanic, we cut the brown wire at the alternator, and ran a 12V+ wire from the battery onto it, nothing really changed. It charged really well at first, impressively well (this has happened before) and i turned on all the lights and it worked nicely. I then waited a bit to be sure, after a couple minutes choke went off, and it still charged well, i turned my lights, radio on etc. and then suddeny it dropped again, down to 12,6-7V and when i tried to rev the engine up to 1500-2000 rpm it only dropped even more, and then built up again when letting of the throttle. I ended up wiring everything back up again. I also tried to hook up a jumping cable from negative on the battery to a good ground on the engine block, nothing changed, however im thinking of replacing the main ground anyways.

battery also charged well for a bit when i just left the brown wire not attached to anything.
It seems that right after i fully charge up my battery it will charge very well, even with lights, etc. on for a good 5-8 minutes before it drops down to 12-12,5 ish again.

Foxrot; I tried to hook battery cables from my battery (negative) to the engine block on a few dirty/painted surfaces, maybe that wasnt a good test? ... i also have a small differene in charging at the battery and on the alternator, maybe 0,15 volts..

 

[foxtrot]

I have a quick test for you to run, once your charging system is in the 'bad' state. Use the volt meter to check for a voltage drop between your negative battery terminal and the alternator housing. If there is a voltage drop, this would note a bad ground.

 

[MalibuHacon]

Foxtrot, i did that today, it was a small drop, but nothing significant, maybe 0,1-0,2V difference. But I'll replace my ground cables with fresh ones soon 🙂

 

[pontiacgp]

Foxtrot, i did that today, it was a small drop, but nothing significant, maybe 0,1-0,2V difference. But I'll replace my ground cables with fresh ones soon 🙂

the grounds on these cars can cause a number of problems. I upgraded my grounds with a 4 gauge ground from the battery to the body, another to the engine and another to the frame.

 

[MalibuHacon]

What is a four gauge ground? Pontiac

 

[pontiacgp]

4 gauge wire