Due to its structural advantages, the maintenance-free battery consumes very little electrolyte and basically does not need to be supplemented with distilled water during its service life. In addition, it also has the characteristics of shock resistance, high temperature resistance, small size, and small self-discharge, and its life is generally twice that of ordinary batteries.

　　Since the maintenance-free battery uses a lead-calcium alloy grid, the amount of water decomposition and evaporation during charging is small, and the sealing structure of the shell produces less sulfuric acid gas, so it needs to be added. Compared with the traditional battery, it has no corrosion, pole and wire corrosion. , Strong anti-overcharge ability, large starting current, long storage time, etc.

　　Most maintenance-free batteries are equipped with a hole-like liquid (temperature-compensated) hydrometer on the lid, which changes color as the specific gravity of the electrolyte changes. It can indicate the storage condition of the battery and the height of the electrolyte level. If the indicator light on the hydrometer is green, the battery is fully charged and the battery is normal. If the indicator light has few green dots or is white, it means the battery needs to be charged. Light red indicates that the battery is defective and needs to be repaired or replaced. If possible, you can use charging equipment with current-voltage characteristics to charge maintenance-free gel batteries. The device can ensure sufficient power and prevent excessive water consumption due to overcharging.