Cummins/Onan — Battery Service and Charging
Maintenance
From a Cummins/Onan operator's manual covering: 40.0DDB-515R, 50.0DDB-15R, 50.0DDB-9XR. Check it applies to your exact model before use.
Applies to: Cummins/Onan 40.0DDB-515R, Cummins/Onan 50.0DDB-15R, Cummins/Onan 50.0DDB-9XR, John Deere 6329D engine, John Deere 6329D (300-6329D) engine
Before you start
- Do not smoke while servicing batteries; lead acid batteries give off explosive gases while being charged.
Procedure
- Verify cable connections are secure; coat connections with petroleum-based or non-conductive grease.
- Check electrolyte level to split ring mark.
- Measure specific gravity; should be 1.280 at 80°F.
- If distilled water was added or SG is less than 1.280, place batteries on charge until reading reached; do not overcharge.
Tools required
- hydrometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Specific gravity 1.280 at 80°F
Full service-parts list: Cummins/Onan 40.0DDB-515R →, Cummins/Onan 50.0DDB-15R →, Cummins/Onan 50.0DDB-9XR →, John Deere 6329D engine →, John Deere 6329D (300-6329D) engine →
Source: Cummins/Onan operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.