Cummins/Onan — Battery Electrolyte Adjustment for High Temperature Locations
Maintenance
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
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Before you start
- Do not bring an open flame or burning cigarette near the battery during charging; avoid skin or clothing contact with electrolyte. Do not attempt to pour off the electrolyte.
Procedure
- Fully charge the battery.
- While still on charge, draw off all electrolyte above the plates in each cell with a hydrometer or filler bulb.
- Refill each cell with pure distilled water to the recommended level.
- Continue charging for one hour at a 4 to 6 ampere rate.
- Test each cell with a hydrometer; repeat steps 2, 3 and 4 until fully charged reading is not over 1.225.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Dilute from normal 1.275 specific gravity at full charge to 1.225
Source: Cummins/Onan owner'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.