Onan Chronic Battery Discharge / Charging System Issue

Generator battery repeatedly goes dead between exercise cycles or outages

Advertisements

Possible Causes

Failed onboard battery charger, Parasitic DC loads when generator is off, Sulfated or aged battery, Loose battery connections

How to Fix / Troubleshooting

Safety first: Disable auto-start before working on the battery or charger. Use eye protection.

  • Test charger output: With AC power available, measure voltage at the battery. It should be at float level (around 13.2–13.6 V for 12 V systems). If not, troubleshoot or replace the charger.
  • Check for parasitic loads: With the generator off, measure current draw from the battery. Identify and remove any non-essential loads.
  • Battery condition: Load-test the battery. Replace if it fails or is older than the recommended service life.
  • Secure connections: Clean and tighten all battery terminals and ground points.
Advertisements

Repair Difficulty

Easy 2/5

Required Part

Battery Charger Module
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements