The depth of discharge is the degree to which the discharge starts and stops during use. 100% depth means full capacity release. The life of the lead acid battery VRLA is greatly affected by the depth of discharge. The key point of design consideration is deep cycle use, shallow cycle use or floating charge use. If a shallow cycle battery is used for deep cycle use, the lead-acid battery will quickly fail.
Because the positive active material lead dioxide itself is not firmly bonded to each other, lead sulfate is generated during discharge, and it returns to lead dioxide when charged. The molar volume of lead sulfate is larger than that of lead oxide, and the volume of active material expands during discharge. If one mole of lead oxide is converted to one mole of lead sulfate, the volume increases by 95%. In this way, the repeated shrinkage and expansion will gradually loosen the mutual bonding between the lead dioxide particles, which is easy to fall off. If only 20% of the active material of one mole of lead dioxide is discharged, the degree of shrinkage and expansion will be greatly reduced, and the destruction of binding force will be slow. Therefore, the deeper the depth of discharge, the shorter the cycle life.
A large amount of gas is precipitated during overcharging. At this time, the active material of the positive plate is subjected to the impact of gas, which will promote the fall off of the active material; in addition, the alloy of the positive grid is also subjected to severe anodic oxidation and corrosion, so the battery will be shortened when overcharged. Period of use.
vrla lead-acid battery life increases with temperature. Between 10°C and 35°C, for every 1°C increase, about 5 to 6 cycles are added. Between 35°C and 45°C, each 1°C increase can prolong the life for more than 25 cycles. The negative electrode sulfidation capacity is lost and the life is reduced. Battery life increases with temperature over a range of temperatures because capacity increases with temperature. If the discharge capacity does not change, the depth of discharge decreases when the temperature increases, extending the life.
The increase in acid density is beneficial to the capacity of the positive plate, but the self-discharge of the lead-acid battery increases, and the corrosion of the grid also accelerates, which also promotes the loose and shedding of lead dioxide. As the acid density increases in the battery, the cycle life decreases.
As the discharge current density increases, the life of the battery decreases, because the high current density and high acid concentration promote the loose and detached lead dioxide of the positive electrode.
After a new battery is put into use, it must be regularly charged and discharged. The purpose of charging is to restore the capacity of the storage battery in time to meet the needs of electrical equipment. The purpose of discharge is to check the battery capacity parameters in time and to promote the activation reaction of the electrode active material. The quality of charging and discharging of VRLA lead-acid battery will directly affect the electrical performance and service life of the battery. There are many ways to charge the battery, and choosing a scientific and reasonable charging method will greatly improve the maintenance effect of the battery.