Low charge on Pontiac 3.8, 04 Bonneville sedan

New battery and alternator charges 12 volts limit for a few minutes than kills battery.
Asking help on what to look for. All connections are clean and no voltage drop from terminals to ground or positive. Baffled.

What do you mean by “alternator charges 12 volts limit.” A fully charged battery should read at about 12.7V. A properly working alternator should show anything from about 13.5-15V.

From the cryptic little bit of info you provided I’d have to guess that your alternator is dead.

Check the DIM fuse 15 amp located in the rear fuse block under the rear seat cushion to see if it’s blown. If the fuse is good then the trouble might be with computer. The computer regulates the voltage from the generator to the battery.


The battery warning light might be in the circuit for the field and if that is the case make sure it turns on with the other warning lights when you turn the key on. Othewise the exciter inside the alternator won’t work.

Did you reattach the ground wire on the alternator?