As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, BATTERY HOT AND BATTERY OFF LIGHT ILLUMINATED. EMERGENCY CHECKLIST CONSULTED, TURNED BATTERY SWITCH OFF AS A PRECAUTION. PROCEEDED FOR MAINTENANCE. MAINTENANCE REMOVED BATTERY AND INSTALLED SERVIEABLE BATTERY. THE OPS CHECK WAS GOOD AND SET VOLTAGE REGULATOR. (K)