97 malibu battery light.

I have a friend with a 1997 V6 Malibu.. and a couple nights ago, she had come home and shut her car off and everything was fine. The next morning, she started up.. and the battery light was now on. It stayed on for about 10 minutes, then flashed off. Within the next couple minutes, it came on again.. and has been on ever since. The car runs fine, has no symptoms or problems that are noticeable, any ideas??

thanks.

You may have an alternator going bad. check voltage at battery with car running, if not over 13.5 volts, you have a charging system problem. Also check the serp belt and pulleys, belt tensioner may have went bad and isn't keeping the belt tight