What was found
PILOT REPORTED INTERMITTENT STARTING, VOLTAGE FLUCTUATION, AND LOW BATTERY CHARGE. INSPECTION FOUND NR 1 AND NR 2 BATTERY GROUND STRAPS AT AIRFRAME ATTACHMENTS TO HAVE HIGH RESISTANCE AT GROUNDING POINT. CLEANED AREAS AND INSTALLED HARDWARE REFERENCING MOONEY SI M20-97. SYSTEMS CHECKED OK. IT APPEARS THE AIRFRAME PRIMER COATING WAS ACTING AS AN INSULATOR. WHEN REMOVED, THE SYSTEMS OPERATED CORRECTLY.