As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AUTO SHUTDOWN. PERFORMED BITE CHECK ON APU CONTROLLER, NO FAULTS NOTED. PERFORMED VISUAL INSPECTION OF APU AND EXHAUST TAIL PIPE, NO DEFECTS NOTED. DURING APU START BATTERY VOLTS DROP TO 15V AND 36 AMPS. REPLACED BATTERY PER AMM. RAN APU THREE TIMES, OPS CHECKED NORMAL.