Volkswagen Workshop Service and Repair Manuals

Notes:

• ◆ The correct battery electrolyte level is an important factor in ensuring the long life of the battery.
  
• ◆ Batteries with visible min. and max. markings require only a visual check of electrolyte level from the battery exterior.
• ◆ The electrolyte level must be above the minimum marking but not exceed the max. marking.

• ◆ The sealing plugs must be unscrewed on batteries if the exterior min. and max. markings are difficult to recognize, or the electrolyte level is not visible due to the opaqueness of the battery housing. It is then possible to check the electrolyte level by performing a visual check of the inner battery.
• ◆ The electrolyte level must align with the internal electrolyte level marking (horizontal ridge. This equates to the outer max. marking.

Electrolyte level too low

• ◆ When the electrolyte level is too low the cell plates project above the surface and there is a loss of battery capacity (loss of power). If the cell plates are not covered by electrolyte (sulphuric acid) corrosion will occur on the plates, plate bridges and cell connector. The function of the battery cannot be guaranteed if there is corrosion and the battery will become unusable.
  

• ‒ Only top-up with distilled water as this prevents electrolyte impurities which result in an increased self discharge.

Electrolyte level too high

Special tools, testers and auxiliary items

• ◆ →      Commercially available hydrometer

Note:

If the electrolyte level is too high the leaking electrolyte (sulphuric acid/water mixture) will cause damage outside the battery, i.e. to components in engine compartment.

• ‒ If the electrolyte level is too high (overfilled), e.g. above the internal electrolyte level mark (synthetic material web) or above the outer max. marking it is absolutely essential that the excessive electrolyte be extracted with a commercially available hydrometer.
• ‒ Extract the electrolyte using the hydrometer until the electrolyte level reaches the synthetic material web or the max. marking.
  

Batteries with central gas venting