What was found
REPORT OF ELECTRICAL ODOR ON PUSHBACK WITH APU RUNNING. MAINTENANCE ACCESSED THE E&E BAY AND SAW VISIBLE SMOKE COMING FROM THE BATTERIES. THE FLIGHT CREW SHUT DOWN THE AIRCRAFT ELECTRICAL POWER. NO CIRCUIT BREAKERS HAD POPPED. MAINTENANCE FOUND THE RIGHT TERMINAL LUG OUT OF THE APU BATTERY CHARGER LOOSE FROM THE CHARGER SIDE, WHICH CAUSED TO OVERHEAT CONDITION. REPLACED THE APU BATTERY, APU BATTERY CHARGER, BATTERY CURRENT SENSOR, C/B C24622, HEAT BLANKETS, AND WIRE #1101-06. THE AIRCRAFT WAS GROUNDED.