why is the battery indicator light on
Check your connections. There may be corrosion or a cell that is going bad. Perhaps the water level is low? Visual inspection is the first place to start.
Your battery light is on because there is a problem with your charging system. Check battery voltage at the posts of the battery with the car running should have 13-14v if lower then that then you may need a new alternator.
You have a charging system problem. Most likely a faulty alternator.
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