What was found
IN LEVEL FLIGHT AT ALTITUDE, CABIN EMERGENCY LIGHTS STARTED FLASHING ON & OFF FOR REMAINDER OF THE FLT. ARMED EMER BATTS AND FOUND THE LIGHTS TO FLASH. GAINED ACCESS TO BOTH 1 & 2 EMER BATTS, IT WAS NOTED THAT DURING OPS CHECKS 1 (COCKPIT BATT) WAS FOUND INOP. AFTER COMPLYING WITH OPS CHECK, CHARGED. NOTED THAT THEN BATT (AFT LAV) SUCCESSFULLY TOOK A CHARGE, NR 1 BATT FAILED TO TAKE A CHARGE. ELECTED TO REPLACE BOTH BATTS. REMOVED FAULTY NR 1 EMERGENCY BATTERY & INSTALLED TESTED BATTERY IAW MM 33-52-01. REMOVED FAULTY #2 BATTERY & INSTALLED TESTED BATTERY IAW MM 33-52-01. PERFORMED THE OPS TESTED BATTERY IAW MM 33-52-01, WITH NO DEFECTS NOTED.