What was found
BUF - FLT 1605 - EN ROUTE FROM PHL-YYZ, CAPTAIN REPORTED HE HAD LOST BOTH IRU'S AND THAT THE DC FAIL LIGHT WAS ILLUMINATED INDICATING A BATTERY CHARGER PROBLEM. FLIGHT DIVERTED TO BUF AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE FOUND THE BATTERY CHARGER INOPERATIVE. REMOVED AND REPLACED BATTERY CHARGER. ALSO, REMOVED AND REPLACED BATTERY DUE TO VOLTAGE READING LOW. OPERATIONAL CHECK GOOD. (M)