Lead-acid battery: the service life or the cycle times?

　　Although lead-acid batteries are showing a tendency to be replaced on a large scale by lithium batteries, especially lithium iron phosphate batteries that perfectly replace them, lead-acid batteries are still a must in many scenarios. Many users are more confused about the life of lead-acid batteries. Manufacturers generally use the concept of cycle times to explain the life of the battery, but users generally use the service life to determine the life.

　　This has caused many users to fail to understand why the battery's service life is completely different from the number of uses in the actual use process. We must be clear that the life of a battery is related to many factors and cannot be generalized. The following factors affect the life of a lead-acid battery:

　　1. Depth of discharge

　　The depth of discharge refers to the battery's capacity to be discharged before it stops discharging during use. 100% depth of discharge refers to the discharge of the full capacity.

　　The lifespan of lead-acid batteries is greatly affected by the depth of discharge. When designing batteries, engineers consider the key point to be based on different application conditions. The batteries are designed into different formulations such as deep cycle use, shallow cycle use, floating charge use, and high-rate use. And production process.

　　If the shallow-cycle battery is used for deep-cycle use, the lead-acid battery will quickly fail. Because the positive electrode active material lead dioxide itself is not firmly bonded to each other, lead sulfate is generated during discharge, and it is restored to lead dioxide during charging, and the volume of the active material expands during discharge. Such repeated contraction and expansion will lead to a vicious cycle of battery performance. Therefore, the deeper the depth of discharge, the shorter the cycle life of the battery, and the life of the cycle number set during the design cannot be reached at all.

　　2. the degree of overcharge

　　When the lead-acid battery is overcharged, a large amount of gas will be released. At this time, the active material of the positive plate is impacted by the gas, and this impact will promote the active material to fall off. In addition, the positive grid alloy is also subject to severe anodic oxidation and corrosion, so when the battery is often overcharged, the life of the battery will be shortened.

　　3. temperature influence

　　The lifespan of lead-acid batteries increases with increasing temperature. Between 10°C and 35°C, every 1°C increase will increase about 5~6 cycles, and between 35°C and 45°C, every 1°C increase can prolong life by more than 25 cycles.

　　However, when the ambient temperature is higher than 50°C, capacity loss will occur due to the vulcanization of the negative electrode, thereby reducing the life span.

　　4. the influence of sulfuric acid concentration

　　The increase in the density of sulfuric acid is beneficial to the capacity of the positive plate, but the self-discharge of the battery increases, and the corrosion of the grid is also accelerated, which also promotes the loosening of lead dioxide. As the acid density in the lead-acid battery increases, the cycle life decreases. .

　　5. the size of the discharge current

　　As the discharge current increases, the life of the lead-acid battery decreases, because under the conditions of high current density and high acid concentration, the positive lead dioxide is promoted to loosen and fall off.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect substitute for lead-acid batteries, and are the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.