OK, Im driving along and my battery light comes on...so i drive to auto zone to have them test my duralast alternator i bought from them last year. They put the machine on it and tell me to hold the RPMs at 2000 and the machine says its putting out good voltage/current. He said the alternator was fine. next he checked my battery and it said it was fine. but the light is still on. it comes and goes. sometimes it blinks on and off quickly, sometimes it blinks slowly, sometimes its on for 5 minues straight. now, my girlfriend was looking at directions with the map lights on, and i noticed that the dome lights flicker and dim/brighten as the battery light goes on and off. the car always starts, and doesnt ever go "dead". What could be causing this? Im thinking maybe some sort of voltage regulator is going crazy but have no idea. Thanks