Specific Gravity

CAUTION: DO NOT expose a fully discharged battery to freezing temperatures; the battery will be damaged.

NOTE:
- The specific gravity test, in addition to a voltage test under load (described previously) can accurately determine the battery's state of charge.
- Hydrometers are used for testing specific gravity. Check the hydrometer calibration frequently to ensure accuracy

- Test electrolyte in all cells. Average specific gravity should be at least 1.225.
- Correct for electrolyte temperature it necessary:
- For every 10 °F above 80 °F, add 0.004 to hydrometer reading
- For every 10 °F below 80 °F, subtract 0.004 from hydrometer reading

Specific Gravity: % of Charge:

1.265 100 %
1.225 75 %
1.190 50 %
1.155 25 %
1.120 0 %

If specific gravity is above 1.225:
- Load test battery. Testing and Inspection

If specific gravity is below 1.225:
- Charge battery. Service and Repair

If specific gravity varies by more than 0.040 between cells:
- Replace battery. See Service and Repair.