As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ODOR OF SMOKE IN THE COCKPIT, MAIN BATTERY & BATTERY CHARGER MAIN STAUS MESSAGES APPEARED. RETURNED TO LAND. DUMPED FUEL. FOUND MAIN BATTERY CHARGER AT FAULT MAIN 7 APU BATTERY, MAIN & APU BATTERY CHARGER. APU BATTERY DFD MEL 24-31-01B.