What was found
AT CRUISE (30 MIN INTO FLT) FL340 LEVEL ONE ALERT EMERGENCY POWER ON, ON ELECTRICAL SCHEMATIC INDICATIONS NORMAL. BATTERY VOLTAGE INITIALLY NORMAL THEN SLOWLY DECREASED TO 22V (41 INCREASING TO 67 AMP) BATTERY LOW ALERT THEN L EMERGENCY AC OFF SWITCHED EMERGENCY PWR OFF. RECOVERED MOST SYSTEMS FROM GEN PWR. RETURNED TO MEM. REMOVED AND REPLACED L/E BUSS SENSING RELAY R2-5156 AND PERFORMED ADJUSTMENT TEST IAW MD 11 AMM. ALL CHECKS NORMAL ON GROUND OK FOR SERVICE.