As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BATTERY WAS BOOST CHARGED EVERY FLIGHT AND/OR 90 DAYS WHEN IN STORAGE. BATTERY WAS USED FOR NAV LIGHTS AND HOUR METER ONLY (NO STARTER OR GENERATOR ON AIRCRAFT). BATTERY WAS REMOVED FROM AIRCRAFT AND CHARGED AT HOME WITH CONSTANT VOLTAGE CHARGER.