The battery light comes on and off while driving and it scares me. on 2002 Ford Focus

First noticed the light to come on while driving to work. The light came on and then it went off. Took the car that after to get my battery tested. The guy at the auto store told me my battery was bad and put a new battery in. Thought that fixed the problem until I noticed that the light was still going on and off. Took the car to get the battery, starter, and charging system all tested and it all came back normal/good. The battery light however still comes on and off while driving. So what exactly could be causing the problem and if I don't get the issue fixed soon, could I damage my car's system?

by in Antioch, TN on February 23, 2013
2 answers 2 comments
ANSWER by on February 24, 2013
if everyvthing checks out then check for loose connetion
ANSWER by on February 24, 2013
I agree with goodguy's advice to check for loose connections.I personally have replaced alot of focus alternators that were doing EXACTLY what yours is doing due to an internal failure.
COMMENT by on February 24, 2013
The same guy who checked out my alternator told me he didn't notice any loose connections, he said everything was connected. My main concern as I talked to him was how long can I drive before it completely gives out on me. I plan on getting it replaced this week, but I still have to drive back and forth to work and I don't the car to just stop working on especially since it starts up fine and runs fine.
COMMENT by on February 25, 2013
I wish I could tell you how long it would last,but there is no correct guess on that one.