What was found
RIGHT EXTERIOR EMERG LIGHT: PREFLIGHT CHECK WITH BATTERYS OFF AND EMER LTS ON - RT WING INSPECTION LIGHT DOES NOT COME ON. OVERHEAD LIGHT ABOVE SEAT 3 DOES NOT COME ON AND FLOOR LIGHT AT SEAT 3 DOES NOT COME ON. THESE LIGHT DO COME ON WITH BATTERY POWER. RAN PROCEDURE TO RECHARGE BATTERY PACK BUT LIGHTS STILL DID NOT COME ON. CORRECTIVE ACTION: REMOVED ALL 4 EXISTING EMERGENCY LIGHT BATTERIES DUE TO ONE FAILED AND INSTALLED 4 NEW CUSTOMER SUPPLIED EMERGENCY LIGHT BATTERIES IAW MM 33-50-06. OPS CHECK GOOD AT THIS TIME.