1) The electrolyte should be prepared from chemically pure sulfuric acid (or a special electrolyte) and distilled water. The density of the electrolyte is generally 1.25 to 1.29 g/cm3 (at 15°C). Industrial sulfuric acid and plain water cannot be used in batteries because they contain impurities such as iron and copper, which can cause self-discharge and damage the plates.
2) The battery is almost discharged and the electrolyte density is not less than 1.19. When adding liquid, choose to add distilled water to the lowest mark, then add pure sulfuric. acid (or special electrolyte) so that the specific gravity is about 1.2, the amount of liquid added does not exceed the upper limit scale.
3) After the electrolyte is injected into the battery, let the battery sit for 3-6 hours until the electrolyte temperature is lowerre at 35°C before charging.
Charging time is approximately 3 to 4 hours. During the charging process, when the battery cell voltage increases by 2.4V, more bubbles begin to appear in the electrolyte. The charging current must then be reduced by half. After charging, a discharge test should be carried out to avoid sulfide damaged batteries that are only superficially charged and cannot actually be used. Therefore, the battery should be observed before charging and should be replaced if sulfide precipitation occurs.
4) When full, the relative density of the electrolyte is adjusted to: when the ambient temperature is 30-40°C, the relative density of the electrolyte is 1.270 when the ambient temperature is 20 to 30°C; °C, the relative density of the electrolyte is 1.280; at 20°C below, the relative density of the electrolyte is 1.290.