1. Depth of discharge The depth of discharge is the ext […]
1. Depth of discharge
The depth of discharge is the extent to which the discharge starts and stops during use. 100% depth refers to the discharge of the full capacity. The life of lead-acid batteries is greatly affected by the depth of discharge. The focus of design considerations is deep cycle use, shallow cycle use or floating charge use. If shallow cycle batteries are used for deep cycle use, The lead-acid battery will quickly fail.
Because the positive active material lead dioxide itself is not well-bonded with each other, lead sulfate is generated during discharge, and returns to lead dioxide during charging. The molar volume of lead sulfate is larger than that of lead oxide, and the volume of the active material expands during discharge. If one mole of lead oxide is converted to one mole of lead sulfate, the volume increases by 95%. Such repeated contraction and expansion will gradually loosen the mutual bond between the lead dioxide particles and easily fall off. If only 20% of the active material of one mole of lead dioxide is discharged, the degree of contraction and expansion will be greatly reduced, and the destruction of the binding force will become slow. Therefore, the deeper the depth of discharge, the shorter the cycle life.
2. Overcharge level
A large amount of gas is precipitated during overcharging. 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 the battery will cause The application period is shortened.
3. The influence of temperature
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. Between 35°C and 45°C, every 1°C increase can prolong life by more than 25 cycles. If it is higher than 50°C, The vulcanization capacity of the negative electrode is lost and the life is reduced.
Battery life increases with increasing temperature within a certain temperature range because the capacity increases with increasing temperature. If the discharge capacity does not change, the depth of discharge decreases when the temperature increases, and the solid life is extended.
4. The influence of sulfuric acid concentration
Although the increase in acid density is beneficial to the capacity of the positive plate, the self-discharge of the battery increases and the corrosion of the grid accelerates, which also promotes the loosening of lead dioxide. As the acid density in the battery increases, the cycle life decreases.
5. The influence of discharge current density
As the discharge current density increases, the battery's lifespan decreases, because under the conditions of high current density and high acid concentration, the positive lead dioxide is promoted to loosen and fall off.