What was found
TAXIING FOR FLIGHT 9805 DURING THUNDERSTORM WITH AIRCRAFT POWER OFF THE EMERGENCY LIGHTS CAME ON APPROX 1 1/2 HOURS, THEN LIGHTS WENT OUT. CAME OUT POWERED UP PLANE TESTED EMERGENCY LIGHTS AND ALL EMERGENCY LIGHTS ON PLANE FROM ROW 8 TO BACK DIMMED OUT AFTER A FEW SECONDS. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED ALL EMERGENCY BATTERIES NR 1, 2, 3 & 4 IAW EMB 33-50-04. THE AIRCRAFT WAS RETURNED TO SERVICE.