What was found
(CAN) SMOKE OR MIST COMING OUT VENT HOLE FROM MAIN E/E DOOR ON WALK AROUNDFOUND THE MIST COMING FROM THE MAIN BATTERIES, WHO WERE FOUND TO BE OVER CHARGED, NO ABNORMAL BATTERY INDICATION NOTED IN FLIGHT. BOTH BATTERIES WERE CHANGE ALSO AS THE BATTERY CHARGER, OPERATIONAL CHECK CARRIED OUT, FOUND SERVICEABLE.