Electrolyte level - 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: .
- Only use flashlight to illuminate inside of battery casing.
- Never illuminate inside of battery casing with a naked flame.
- Keep naked flames and burning cigarettes away from batteries.
- 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
- Battery filler bottle VAS 5045
- Hydrometer (commercially available)
The correct electrolyte level is an important factor in ensuring long battery service life.
- On batteries with visible min. and max marks it is sufficient to perform visual inspection from outside to check electrolyte level.
- The electrolyte level must be above the minimum marking but not exceed the max marking.
- On batteries on which the min. and max marks are difficult to see, or on which the electrolyte level cannot be seen because of the opacity of the battery housing, remove the sealing plugs.
- Check the electrolyte level by making a visual inspection of the inside of the battery.
- The electrolyte level must coincide with the internal level mark (plastic web). This corresponds to the max marking on the outside.
Electrolyte level too low
If the electrolyte level is too low, drying-out of the cell plates will reduce the capacity (power) of the battery. The cell plates must be fully covered by electrolyte (sulfuric acid/water mixture) in order to prevent corrosion of plates, plate bridges and cell connectors. Such corrosion would impair battery operation and make the battery unusable.
- If electrolyte level is too low, use battery filler bottle VAS 5045 to add distilled water until max mark is reached.
NOTE:
- Filler neck of battery filler bottle VAS 5045 is designed to prevent over-filling of battery cell and electrolyte spills. When the maximum filling level is reached, the flow of distilled water into the battery cell is cut off.
- Use distilled water only, this prevents contamination of the battery electrolyte and the associated increase in self discharge.
- Screw sealing plugs of battery cells back in again.
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.
Electrolyte level too high
If the electrolyte level is too high (overfilled), escaping electrolyte (sulfuric acid/water mixture) will cause damage outside the battery.
- If the electrolyte level is above the inner level mark (the plastic web) or the outer max mark, it is essential to drain some off.
- Remove the battery cell sealing plugs.
- Use a commercially available hydrometer to drain off the sulfuric acid until it has fallen to the level of the plastic web or the max mark as appropriate.
- Screw sealing plugs of battery cells back in again.
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.