Specific Gravity, Checking

Specific Gravity, Checking

Special tools, testers and auxiliary items







- Commercially available hydrometer
- Cleaning cloths

WARNING:
- When handling sulfuric acid it is important to observe accident prevention procedures. Suitable protective clothing must be worn.
- When disposing batteries it is important to use the proper disposal methods for batteries and sulfuric acid.

NOTE:
- In conjunction with the "voltage underload" test, the specific gravity test gives a good indication of the battery condition.
- The temperature of the electrolyte in the battery must be at least 10 degrees C.
- The specific gravity can be checked immediately after charging battery.

The specific gravity must be checked in all battery cells as follows:

- Switch off ignition.
- Remove all battery plugs (battery cell sealing plugs).







- Immerse end of hydrometer in a cell and extract sufficient electrolyte so that float swims free in the electrolyte.

- The greater the specific density of the extracted electrolyte, the higher the float rises
- The density in kg/cu.dm can be read off the scale of the hydrometer (specific density of electrolyte)

- Read off measured value on hydrometer and compare with table:



Charge condition in normal climates Specific gravity in kg/cu.dm
Discharged 1.12
Half charged 1.20
Well charged 1.28

Charge condition in tropical climates Specific gravity in kg/cu.dm
Discharged 1.08
Half charged 1.16
Well charged 1.23

In countries with normal climates the specific gravity must be at least 1.24 kg/cu.dm.

- If the specific gravity is too low, charge the battery.
- After charging the battery, repeat the specific gravity test.

NOTE: The specific gravity readings for the individual battery cells must not differ by more than 0.03 kg/cu.dm.

Examples of non-acceptable differences between specific gravity levels







Example 1:

- The specific gravity in cell 4 is too low.

Example 2:

- The specific gravity in cells 4 and 5 is too low. The specific gravity readings for the individual battery cells differ by more than 0.03 kg/cu.dm.
- If the specifications are not obtained, replace battery.
- If the specifications are obtained, screw plugs in again.

Always use the original sealing plugs and check they are fully screwed in to make sure that the battery is properly sealed.

Use genuine sealing plugs of the same type if the original plugs are lost or damaged.

Each sealing plug must be installed with an O-ring.