Generator runs but the controller displays E09 and may shut down under load.

Safety first: Turn the generator OFF and disconnect AC input to the charger if separate. High battery voltage can damage electronics.

• Measure battery voltage: With a multimeter, check the battery while the charger is active. Readings above ~14.8 VDC (for standard lead-acid) indicate overcharging.
• Inspect charger settings: Some Hyundai Power chargers have selectable battery type (AGM, GEL, Flooded). Ensure the setting matches your installed battery.
• Check wiring: Verify that the charger positive and negative leads are correctly connected and that the sense wires (if present) are not reversed.
• Replace charger if faulty: If voltage remains too high despite correct wiring and settings, replace the Hyundai Power battery charger module.
• Controller check: If measured voltage is normal but E09 persists, the control module's voltage sensing circuit may be defective and require replacement.