As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH BATTERY SELECTED, DC AMPS FLUCTUATE FROM -1 TO 1. OBSERVED CONTINUOUSLY IN FLIGHT, BOTH IDG OPERATING NORMALLY. NO ILLUMINATION OF BATTERY DISCHARGE LIGHT. ACFT GROUNDED. VERIFIED DEFECT, FOUND ONLY MAIN BATTERY DC AMPS FLUCTUATING. REMOVED AND REPLACED MAIN BATTERY IAW AMM 24-31-11, AND MAIN BATTERY CHARGER IAW AMM 24-31-21. BOTH OPS NORMAL. MAIN BATTERY DC AMPS NOW STEADY.