What was found
BEFORE DEPARTURE TOLD BY CREW THAT APU BATTERY NOT CHARGING. REPLACED APU CHARGER PER MM, NO HELP. NUISANCE MESSAGE. VERIFIED EICAS ADVISORY MESSAGE APU DISCHARGE BLINKS IN & OUT. ALSO THE EICAS MAINT PAGE ( CH 24) SHOWED APU CHARGE & APU DISCHARGE BLINKS. ABOVE VERIFICATION WAS WITH APU RUNNING & STANDBY POWER SWITCHED TO BAT POSITION. T-S REF WDM, SUGGEST REPLACING APU BATTERY CHARGER DISABLE RELAY (R7218). ALSO REF MM SPECIFIC TO THIS RELAY REPLACE. ACCOMPLISHED COMPLETE STANBBY POWER TEST, ALL TESTS NORMAL. ALSO TESTED APU BATTERY. BATTERY DISCHARGES AND CHARGES NORMALLY.