Electrolyte level, checking

WARNING: This page is about a different variant/trim than selected.

Special tools and auxiliary items needed

Fig 1: VAS 5045 Battery Filling Bottle

Courtesy of VOLKSWAGEN UNITED STATES, INC.

VAS 5045 Battery filling bottle (or equivalent)

WARNING:

When checking electrolyte level with sealing caps removed, illuminate the inside of the battery housing/cells with a flashlight.
Keep open flames and sparks away.

The correct battery electrolyte specific gravity is an important factor in maintaining battery performance and service life.

Insufficient electrolyte levels allow cell plates to dry, resulting in a loss of battery capacity (reduced output). If the cell plates are not completely submerged by electrolyte, (sulfuric acid/water mixture) corrosion will occur on the plates, plate bridges and cell connector. Optimum battery function is not possible under these conditions and battery failure results.

If electrolyte level is too high, electrolyte (sulfuric acid/water mixture) may leak out and damage the surrounding area, i.e.: plenum and engine compartment.

CAUTION:

Before beginning repairs on the electrical system

Switch off all electrical consumers.
Switch ignition off and remove ignition key.

Check electrolyte level visually, either via charge indicator (if equipped) or from min./max. markings on battery housing.

Fig 2: Identifying Electrolyte Level Reading On Charge Indicator

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Electrolyte level reading from charge indicator -arrow-.

Green → electrolyte level OK
Colorless or yellow → critically low electrolyte level. Top up with distilled water immediately. Refer to Electrolyte level too low

CAUTION:

Do not use charge indicator to determine excessive electrolyte levels. Always check for excessive electrolyte levels visually.

Fig 3: Electrolyte Level Reading From Min./Max. Marking On Battery Housing

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Electrolyte level reading from min./max. marking on battery housing -arrow-.

Electrolyte level must be above the minimum marking or just reach the maximum marking.

If no minimum and maximum markings are visible on the battery housing (either not molded-in or not visible due to installation location) or if the battery housing is black, the sealing plugs must be removed. Then determine electrolyte level by viewing inside the battery cells.

First remove plastic foil from cell caps (where applicable), being sure not to disturb plastic safety warning label on battery.

Fig 4: Charge Indicator & Battery Cell Caps

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Unscrew cell caps -2-.
Look into individual battery cells to determine electrolyte level.

Fig 5: Internal Electrolyte Level Indicator (Lip)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Electrolyte level must align with the internal electrolyte level indicator (lip) -1-. This equates to the external "maximum" marking on the battery case.

NOTE: On batteries with black housings, obtain accurate electrolyte level readings by illuminating inside of cells with a flashlight.

Electrolyte level too low. Refer to Electrolyte level too low

Electrolyte level too high. Refer to Electrolyte level too high

No load voltage, checking. Refer to No load voltage, checking

Battery test. Refer to Battery, testing