Engine shuts down or will not start; code indicates low system voltage; control panel may flicker.

Safety: Isolate AC output and disable auto-start before working on DC circuits.

• Measure battery voltage: With a multimeter, check voltage at the battery posts. If below 12.0 V (12 V) or 24.0 V (24 V), charge the batteries fully and retest. Replace batteries older than their service life or that fail load testing.
• Inspect charger: For standby sets, verify the shore-powered battery charger (Volvo Penta or OEM) is energized and outputting correct float voltage (typically ~13.5–13.8 V or 27–27.6 V). Check AC supply, fuses, and charger status LEDs.
• Clean and tighten connections: Remove corrosion from battery posts and cable lugs. Tighten all connections at the battery, starter motor, and ground points.
• Check engine alternator: Start the engine (if possible) and measure charging voltage at the battery. It should rise to around 14 V (12 V system) or 28 V (24 V system). If not, inspect alternator belt tension and wiring. Replace a failed alternator with a Volvo Penta-approved unit.