2002 Ford Escape Battery Light comes on and stays on

There still may be a dead battery cell or a failing alternator as a 12v battery is actually 13.6v at full charge and alternator running should be around 14+ volts charging voltage. I would have the both load tested and replace battery terminals & terminal wires if corroded or tighten & clean. It may just be time for a new battery as these 5 year batteries would mean 15 years and three batteries from 2002 which is now 2017. There you go.

Could thereb something else?likr the abs