Alternator charger problem

[GT35065]

Thanks Blas and Rich. Car is #1108 and I've had it for 10 years. Got a new battery as the one I had was 3 1/2 years old and still had some warranty left for trade.

Did not solve the problem. Battery is fine with no accessories on, the volts go from 12.7 before running to 13.7-13.8 with engine running. If headlights alone are turned on, the battery is still charging at around 13.4 while running. When the fans are on with the headlights, volts drop to 12.4 which is discharging the battery. I can check the ground. I can see where it is grounded near the starter motor. Don't know if ground would be the issue when car starts just fine, but still worth checking. Out put at the alternator is 14.2, so it seems to be working.

Battery in regular lead acid, and I normally use trickle chargers unless driving regularly. Other thing is this may have been going on for a while because a rarely drive the car at night with fans and headlights on. This is when I had the issue when recently doing this and battery wouldn't start car after driving for 40 minutes.

Rick