Only distilled water should be used for topping up: tap or boiled water contains conductive salts and other minerals that cause damage to the battery.
Warning! Battery electrolyte is dangerous. If it gets into your eyes, on your skin or clothes, wash it off with plenty of water. If necessary, seek medical attention.
If the vehicle is equipped with a maintenance-free battery (there are no holes on the top), there is no need to service the battery. Such batteries use a special gel electrolyte, so there is no need to check the level and density of the electrolyte. Such batteries cannot be disassembled.
Sequence of works
Text republished from the website: www.mercedesman.ru
"15,000 km annually"
1. The electrolyte level in the battery must not be below the "MIN" mark on the case (the upper edges of the electrodes must be covered with electrolyte).
2. If the electrolyte level is insufficient, unscrew the plug or pry it off with a screwdriver.
3. Add distilled water to the charged battery up to the upper mark (about 15 mm above the top edge of the electrodes).
4. In a deeply discharged battery, the water should only cover the upper edge of the electrodes. When charging, the level increases significantly. After charging, add water to the upper mark.
5. Do not allow overfilling - in this case, the electrolyte will come into contact with the cover or leak out of the side vents. This will cause corrosion and the formation of acid crystals on the surface of the battery and the platform on which it is installed.
Contact service
1. Wash off traces of oxidation on the battery contacts with a warm soda solution or treat with a special compound Neutralon from Varta.
2. Treat the battery contacts and wire terminals with Bosch Ft 40v1 protective compound.
Caution: Do not apply grease to contacts or terminals.
3. The top of the battery must always be dry, otherwise leakage currents will occur between the cells and the battery will begin to discharge.