What was found
APU INOP. APU AUTO SHUTSDOWN AFTER REACHING 36% RPM.(<P>PERFORMED ECU BITE PROCEDURE PER B767 FIM 49-11 FAULT TREE 987. NO MINI FLAGS. PERFORMED BITE PROCEDURE OF APU ECU IAW B767 FIM 49-11 PT 987, NO FAULTS FOUND. WHEN STARTING APU BATT VOLTAGE STAYS ABNORMALLY LOW DURING ENTIRE START. SUSPECT BATTERY CHARGER AND/OR BATTERY. REMOVED AND REPLACED APU BATTERY CHARGER IAW AMM 24-31-05. OPS CHECK GOOD. REMOVED AND REPLACED THE APU BATTERY IAW AMM 24-31-04. OPS CHECKED GOOD.