Battery light comes on & goes off has new battery & alt checks out ok. on 1999 Oldsmobile Alero

Dash light comes on after car is on and moving. Goes off after a couple of seconds. Had new battery put in and checked starter & alternator. Both are good. Light is now staying on longer but still goes off in less than one minute.

1 answer
Most likely the alternator is starting to go. It may test ok because they generally don't put much load on it and it's a very short test cycle.
Most likely the alternator is starting to go. It may test ok because they generally don't put much load on it and it's a very short test cycle.