Cummins/Onan — Checking Battery Specific Gravity
Maintenance
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DQAD, Cummins/Onan DQAE, Cummins/Onan DQAF, Cummins/Onan QSM11 engine
Before you start
- Electrolyte is a dilute sulfuric acid that is harmful to the skin and eyes. Wear goggles and protective, rubber gloves and apron when servicing batteries.
Procedure
- Use a battery hydrometer to check the specific gravity of the electrolyte in each battery cell.
- Hold the hydrometer vertical and take the reading.
- Correct the reading by adding four gravity points (0.004) for every ten degrees the electrolyte temperature is above 80 F (27 C).
- A fully charged battery will have a corrected specific gravity of 1.260.
- Charge the battery if the reading is below 1.215.
Tools required
- Battery hydrometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Corrected specific gravity fully charged 1.260
- Charge if reading below 1.215
- Add four gravity points (0.004) per ten degrees above 80 F (27 C)
Full service-parts list: Cummins/Onan DQAD →, Cummins/Onan DQAE →, Cummins/Onan DQAF →
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.