As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUX BATTERY READING 2 AMPS DRAW. PERFORMED AUX BATTERY CHARGER OPERATIONAL TEST PER M/M 24 31 31 710 801 TESTS WITHIN LIMITS. AUX BATTERY STILL 27 VOLTS 2 AMP CHARGE. REPLACED AUX BATTERY REF M/M 24 31 11 TEST NORMAL. AFTER APPROX 20 MINUTES AUX BATTRY READS 28 VOLTS 0 AMP CHARGE.