The electrolyte level in all cells must be between the marks "MIN" And "MAX", applied to the translucent battery case. If there are no marks, then the electrolyte level should be 5–10 mm above the upper edge of the separators.
To restore the electrolyte level, add only distilled water. If it is determined that sloshing is the cause of the low level, then add electrolyte of the same density as that left in the battery cell. If the level is above normal, then suck out the electrolyte with a rubber bulb with an ebonite tip.