Specific Gravity

Specific Gravity, Checking


NOTE:
- The following procedure only applies to batteries without charge indicator
- In order to better determine a battery's overall condition, it is recommended to perform always the electrolyte specific gravity test in conjunction with the load test. Component Tests and General Diagnostics


WARNING!
- Before working with electrolyte, refer to Warnings and Safety Measures.
- Dispose of electrolyte (sulfuric acid) properly! Waste electrolyte must only be disposed of in appropriate waste disposal sites. Refer to local regulations pertaining to electrolyte disposal
- The following notes and procedures must be followed to ensure correct measurements.


Special tools, testers and auxiliary items







- Commercially available hydrometer
- Shop rags


NOTE:
- Minimum battery temperature of 10 °C (50 °F) is required when carrying out specific gravity tests.
- Specific gravity of all cells must be checked.


- Switch ignition off
- Remove all battery cell caps.







- Dip end of hydrometer into cell and extract sufficient electrolyte to allow indicator float to swim freely (the greater the electrolyte density in kg/cubic dm, the higher the indicator float position). Note each cell's specific gravity reading from float -arrow-. Repeat sequence until all cells are checked.
- Review noted values and compare with values in table below:

Charge condition Specific gravity
(normal climate) in kg/cubic dm

Discharged 1.15
Half charged 1.22
Fully charged 1.28

Example 2: 1.26 1.26 1.25 1.14 1.18 1.24

Example 1: Specific gravity in cell 4 (1.10) is too low.

Example 2: Specific gravity in cells 4 (1.10) and 5 (1.18) are too low and variation between cells exceeds 0.04 kg/cubic dm.

If specific gravity specifications are not met, replace battery.

If specific gravity specifications are met, reinstall cell caps.


CAUTION!
Only the use of genuine VW battery cell caps ensures the different battery cover systems are sealed correctly. Only use genuine cell caps of the same construction if lost or damaged. All cell caps must be equipped with an O-ring seal.