With the popularity of high frequency switching power supply, valve-regulated lead -acid battery is widely used in the electrical system due to its high cost performance, security, and supplying large current. Owing to its sealed, no added water maintenance, the VRLA battery is also called “maintenance-free” lead acid battery. Because the capacity of the battery is not enough or failure, it generates many power supply accidents of substation, computer system, and instrument automation system. Hence, it is very important for us to know the influence factors to help properly use the VRLA battery and prolong its life.