If a fully charged battery is left unused for a long time, it will gradually lose power. This phenomenon is called head discharge. For a fully charged battery, if the capacity is not reduced by more than 2% per day, that is normal self-discharge, and more than 2% is faulty. The main causes of self-discharge are: 1 Electrolyte impure, the potential difference between the impurities and the plate and the different impurities sinking on the plate, through the electrolyte to generate partial discharge; 2 electrolyte overflow of the battery in the lid On the board, the positive and negative poles form a path; the active material on the 3 pole plate falls off, and the excessive sediment on the lower plate shorts the pole plate; 4 The battery is not placed for a long time, the sulfuric acid sinks, the specific gravity at the lower part is larger than the upper part, and the potential at the lower part of the pole generates potential. Poor self-discharge caused by the difference. After the self-discharge failure occurs, the electrolyte should be poured out, the plate assembly removed, the separator removed, and the plates and separators rinsed with distilled water, and then reassembled and refilled with new electrolyte.