Adding electrolyte to the battery (Mercedes-Benz E-Class W123)

If, with a fully charged battery, the specific gravity of the electrolyte in one of the cells is 0.040 or more lower or higher than in the others, the cause may be an electrolyte leak from that cell. Add a solution of 1 part sulfuric acid and 2.5 parts distilled water to the cell. If the electrolyte level in it is already at the upper mark, suck out the electrolyte with a hydrometer. When mixing sulfuric acid with water it is not allowed to pour water into acid; always pour the acid in a thin stream into a glass container with water. When water is poured into sulfuric acid, an explosion will occur. Fill the element with fresh electrolyte, recharge the battery and check the density of the electrolyte.