The main factors affecting the lifespan of valve regulated sealed lead-acid batteries are: (1) discharge depth. Valve regulated sealed lead-acid batteries are lean liquid batteries. With the increase of discharge time, the internal resistance of the battery increases rapidly and the terminal voltage decreases significantly. When the power generation termination voltage specified by the manufacturer is reached, the discharge should be immediately terminated and charged as required, otherwise it may cause over discharge. If the discharge is repeated, even after recharging, the capacity is difficult to recover, ultimately resulting in a shortened service life. (2) Discharge current rate. The charging and discharging of valve controlled sealed lead-acid batteries should be carried out according to the specified requirements. If a small current is used for discharging, the effective substances in the deep layer of the electrode plate can participate in the reaction, and then a large current is used for charging. The chemical reaction is only carried out on the surface, which will shorten the service life of the battery. (3) Float charging. If the float charging voltage is set too low, it will shorten the current life of the battery due to insufficient charging, causing it to sulfurize several hundred times. If the float charging voltage is set too high, the battery will be in an overcharged state for a long time, causing damage to the battery partition, electrode plate, etc. due to electrolytic oxidation, accelerating the corrosion of the battery grid, loosening the active substance, and reducing the capacity. When the floating charge current is too high, the heat generated in the battery cannot be dissipated in a timely manner, and heat accumulation will occur in the battery, causing the temperature of the battery to rise. This in turn promotes an increase in the floating charge current, ultimately leading to a vicious cycle of continuous increase in battery temperature and current, which is the phenomenon of thermal runaway. (4) Charging current rate. During high current charging, the rate of gas generation inside the battery will exceed the rate of gas absorption by the battery. The internal pressure of the battery will increase, and the gas will be discharged from the safety valve, causing a decrease or drying of the electrolyte. Typically, a 15% loss of water results in a 15% reduction in battery capacity. Excessive loss of moisture will prematurely terminate the service life of valve regulated sealed lead-acid batteries. In addition, factors that affect battery life include charging equipment, temperature, sealing, etc. In summary, the oxygen generated from the positive electrode plate quickly reacts with the active substance of the negative electrode during charging and recovers into water. Therefore, valve regulated sealed lead-acid batteries can be exempted from maintenance by adding water, which is also why valve regulated sealed lead-acid batteries are called "maintenance free" batteries. However, the meaning of "maintenance free" does not mean that no maintenance is required. On the contrary, in order to improve the service life of valve regulated sealed lead-acid batteries, valve regulated sealed lead-acid batteries are not only exempt from water addition, but also have the same maintenance as regular lead-acid batteries. Only when used properly and maintained correctly can valve regulated sealed lead-acid batteries achieve their expected service life