Electrolyte specific gravity - batteries with sealing plugs, checking
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
- Prior to handling or servicing batteries, read, understand and observe the Warning and Safety Measures for lead-acid batteries Smoking, naked flames, fires and sparks: .
- Always wear suitable protective clothing Eye protection and protective clothing: .
- When disposing of batteries, always pay attention to the appropriate regulations for batteries and sulfuric acid.
- Proper battery sealing plugs must be used to ensure differing battery cover systems are sealed correctly. Use genuine sealing plugs of same construction if lost or damaged.
- The plugs must be installed with an O-ring seal.
Special tools, testers and auxiliary items required
- Hydrometer (commercially available)
NOTE:
- The electrolyte specific gravity test in conjunction with the battery test provides specific information on battery condition.
- The temperature of the battery electrolyte must be at least 10 ° C.
- Electrolyte specific gravity can be checked immediately after charging battery.
Test sequence
- 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 gravity of the electrolyte drawn in, the higher the float will ride.
- The specific gravity in kg/dm 3 (specific gravity of electrolyte) can be read off the scale - arrow - on the hydrometer.
- Take reading on hydrometer and compare to values given in table:
| Charge condition in normal climatic zones | specific gravity of electrolyte in kg/dm 3 |
| discharged | 1.12 |
| half charged | 1.20 |
| well charged | 1.28 |
| Charge level in tropical countries | specific gravity of electrolyte in kg/dm 3 |
| discharged | 1.08 |
| half charged | 1.16 |
| fully charged | 1.23 |
The specific gravity in normal climatic zones must be at least 1.24 kg/dm 3 . If specific gravity is too low in all battery cells:
- Charge battery and then repeat electrolyte specific gravity test.
Example 1:
| Battery cell: | 1 | 2 | 3 | 4 | 5 | 6 |
| specific gravity per cell in kg/dm 3 | 1.24 | 1.25 | 1.25 | 1.10 1) | 1.24 | 1.25 |
|
||||||
* specific gravity in cell 4 is too low (deviation greater than 0.03 kg/dm 3 )
Example 2:
| Battery cell: | 1 | 2 | 3 | 4 | 5 | 6 |
| specific gravity per cell in kg/dm 3 | 1.26 | 1.26 | 1.25 | 1.14 1) | 1.18 1) | 1.24 |
|
||||||
* specific gravity in cells 4 and 5 is too low (deviation greater than 0.03 kg/dm 3 )
If specifications are not obtained:
- Replace battery.
NOTE:
- The measured values for the electrolyte specific gravity of the individual battery cells must NOT deviate by more than 0.03 kg/dm 3 , otherwise battery has to be replaced.
- Reinstall battery sealing plugs.
CAUTION:
- Battery openings must be fitted with the correct plugs to ensure that battery cover (different types!) is properly secured. Always use correct sealing plugs (same as original equipment) in the event of loss or damage.
- The plugs must be equipped with an O-ring seal.