Electrolyte level, 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.

WARNING:

Observe accident prevention directions when handling electrolyte.

Appropriate safety clothing is required.

Illuminate the inner part of the battery housing using only a flashlight.

Never illuminate the interior of the battery housing using an open flame.

Keep open flames and burning cigarettes away from batteries.

When disposing of batteries, always observe the appropriate regulations for batteries and sulfuric acid.

To ensure proper sealing of the different battery plug systems, it is necessary that the original battery plugs are tightened into the battery openings. In case of loss or damage, only original sealing plugs of the same type may be used.

The plugs must be installed with an O-ring seal.

Special tools and equipment

Fig 1: Battery fill bottle VAS 5045

Courtesy of VOLKSWAGEN UNITED STATES, INC.

VAS 5045 battery fill bottle
Hydrometer, commercial type

NOTE:

Maintaining the correct electrolyte level in the battery is an important factor affecting the length of the battery's service life.
Batteries which have visible minimum and maximum marks require only visual inspection of the outside of the battery to check the electrolyte level.
The electrolyte level must be above the minimum mark, but may extend only as far as the maximum mark.
If external min.. and max. marks on a battery are not readily visible, or if electrolyte level cannot be checked properly due to an opaque battery casing, battery caps must be unscrewed. It is then possible to check electrolyte level by performing a visual internal check of battery.
The electrolyte level must stop at the inside electrolyte level mark (plastic web). This corresponds to the exterior max. mark.

Fig 2: Locating Magic Eye

Courtesy of VOLKSWAGEN UNITED STATES, INC.

For batteries with a charge indicator -arrow-, the electrolyte level can be read from the color indication.
Test sequence. Refer to Battery with charge indicator .

Electrolyte level too low

NOTE: Too low an electrolyte level causes a loss of battery capacity (power), due to cell plates drying out. If the cell-plates are not surrounded with electrolyte (sulfuric acid), the plates, plate bridges, and cell connectors will corrode. The battery will not function as a consequence of this corrosion, and will become unusable.

Fig 3: VAS 5045 Battery Filling Bottle

Courtesy of VOLKSWAGEN UNITED STATES, INC.

If electrolyte level is too low, top off to max. mark with distilled water using battery fill bottle VAS 5045.

NOTE:

The filler neck of the filler VAS 5045 is designed to prevent over-filling of the battery cell and electrolyte leakage. The flow of distilled water into the battery cell is interrupted on reaching the max. level.
Always use distilled water for topping off to prevent electrolyte contamination which results in increased self-discharge.
Reinsert all battery cell sealing plugs. Refer to Batteries with central gas venting , batteries with central gas venting.

Electrolyte level too high

NOTE: If the electrolyte level is too high, the electrolyte (a mixture of sulfuric acid and water) escapes and causes damage outside the battery, i.e. to components in engine compartment.

Fig 4: Identifying Commercially Available Hydrometer

Courtesy of VOLKSWAGEN UNITED STATES, INC.

If electrolyte level is too high (overfilled), i. e. if level is above inside mark (plastic web) or above outer max. mark, electrolyte must be drawn off using a commercially available hydrometer.
Extract electrolyte using hydrometer until remaining fluid is level with plastic indicator web or max. mark.
Reinsert all battery cell sealing plugs. Refer to Batteries with central gas venting , batteries with central gas venting.