Hi i have focus 2010 shape. Red battery light came on mechanic said need new alternator. I got alternator replaced with new one but battery light come on when i start engine after car is parked for more then an hour and it takes 5 to 10 mins to go off again when engine is running. I got my battery changed but still got same problem. Can anyone tell why battery light comes on when i start the engine after car is parked for couple of hours and goes off after 5 to 10 mins when engine is running?