As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELEC LIGHT ON LANDING. GROUNDED - YES. P5-13 PANEL BITE SHOWS "BAT CHGR INOP" INTERMITTENT FAULT. CLEARED FAULT. BATTERY CHARGER (M5) CHECKS GOOD PER B737-800 FIM 24-31 TASK 829. STARTED APU ON BATTERY AND VERIFIED BATTERIES ARE CHARGING. GROUND VERIFICATION COMPLETE REF FIM 24-31, AIRCRAFT OK FOR SERVICE.