Onan
Chronic Battery Discharge / Charging System Issue
Generator battery repeatedly goes dead between exercise cycles or outages
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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.
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Repair Difficulty
Easy
2/5
Required Part
Battery Charger Module
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