Electrolyte Level Check

The battery electrolyte consists of sulphuric acid diluted with distilled water. Some of this water may evaporate or decompose during charging into hydrogen and oxygen.

Audi 80 models are fitted with a maintenance-free battery conforming to standard DIN 72311, which has a relatively large water reserve. Under normal conditions, it should not require topping up with distilled water over its entire service life. Increased water consumption is caused only by high ambient temperatures, prolonged stays in hot regions (vacation), a faulty generator voltage regulator, self-discharge during long periods of parking, or deep discharge caused, for example, by parking lights left on all night.

PROCEDURE

The electrolyte in the battery must reach at least the lower mark on the case, marked by paint or embossed, but at minimum must well cover the upper edges of the plates.

If the electrolyte level is low, remove the cap.

If the battery is charged normally, add distilled water up to the upper mark or 15 mm above the upper edges of the plates.

If the battery is heavily discharged, add only enough water to cover the plates from above, because the electrolyte level will rise considerably during recharging.

Top up to the upper mark only after charging.

The amount of water from the filler bottle must be metered carefully, because the battery is easily overfilled.

An overfilled battery will "boil", and acid will emerge at the cap.