Electrolyte density in all cells, checking
WARNING: This page is about a different car, the 2002 Audi S4. However, it is still accessible from the selected car via links, so may be relevant.
Special tools and equipment
- Hydrometer, commercial type
WARNING:
Always pay attention to accident prevention regulations when handling electrolyte. Suitable protective clothing must be worn.
When disposing of batteries it is absolutely necessary that disposal procedures for batteries and sulfuric acid are observed.
NOTE:
- In conjunction with "voltage under load" test, electrolyte density test gives a good indication of battery condition.
- Electrolyte temperature must be at least 10 ° C.
- The electrolyte density can be checked immediately after battery charging.
Test sequence
- Remove all battery plugs (battery cell sealing plugs).
- Immerse hydrometer in one of the cells and draw in electrolyte until float is freely suspended in electrolyte.
- The greater the specific density of electrolyte drawn in, the higher the float will sit.
- The specific gravity in kg/dm3 can be read off from the hydrometer scale.
- Read off measured value on hydrometer and compare with values listed in table:
| Charge condition in normal climatic zones | Specific density in kg/dm3 |
| discharged | 1.12 |
| half charged | 1.20 |
| well charged | 1.28 |
| Charge level in tropical countries | Specific density in kg/dm3 |
| discharged | 1.08 |
| half charged | 1.16 |
| well charged | 1.23 |
Specified gravity of electrolyte must be at least 1.24 kg/dm3 in normal climate zones.
- If the specified gravity in all battery cells is too low, charge battery.
- Repeat specified gravity test after charging battery.
- If the specified values are not reached, replace battery.
NOTE:
The measured values for the acid density for individual battery cells may not deviate more than 0.03 kg/dm3 from each other, otherwise replace battery.
| Battery cell: | 1 | 2 | 3 | 4 | 5 | 6 |
| Electrolyte density per cell in kg/dm3 | ||||||
| Example 1: | 1.24 | 1.25 | 1.25 | 1.10 | 1.24 | 1.25 |
| Result: Specified gravity in cell 4 is too low (deviation is greater than 0.03 kg/dm3) | ||||||
| Example 2: | 1.26 | 1.26 | 1.25 | 1.14 | 1.18 | 1.24 |
| Result: Specified gravity in cells 4 and 5 is too low (deviation is greater than 0.03 kg/dm3) | ||||||
- If the specified values are reached, reinsert battery caps.
CAUTION:
It is essential that genuine and proper battery sealing plugs be used to ensure that different 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.