What is overcharging and how does it affect battery performance?
Overcharge refers to the behavior of continuing to charge the battery after it has been fully charged in a certain charging process. Since the capacity of the negative electrode is higher than that of the positive electrode in the design, the gas from the positive electrode permeates through the separator paper and recombines with the cadmium from the negative electrode. Therefore, under normal circumstances, the internal pressure of the battery will not increase significantly, but if the charging current is too large, or the charging time is too long, the oxygen that appears is too late to be consumed, which may cause the internal pressure to rise, battery deformation, and liquid leakage, and other undesirable phenomena. At the same time, its electrical performance will also be significantly reduced.
What is over-discharge and how does it affect battery performance?
Over-discharge means that the battery has discharged the internally stored power, after the voltage reaches a certain value, continuing to discharge will cause over-discharge. The discharge cut-off voltage is usually determined according to the discharge current. 0.2C-2C discharge is generally set to 1.0V/branch, and above 3C such as 5C or 10C discharge is set to 0.8V/branch. Overdischarge of the battery may bring catastrophic damage to the battery consequences, especially large current over-discharge, or repeated over-discharge will have a greater impact on the battery. Generally speaking, over-discharge will increase the internal pressure of the battery, and the reversibility of the positive and negative active materials will be destroyed. Even if it is charged, it can only be partially restored, and the capacity will be significantly attenuated.
What problems will occur when batteries of different capacities are used in combination?
If you mix old and new batteries with different capacities, liquid leakage and zero voltage may occur. This is because during the charging process, the capacity difference causes some batteries to be overcharged during charging, and some batteries are not fully charged. During discharging, some batteries with high capacity are not fully discharged, and batteries with low capacity are over-discharged. In such a vicious circle, the battery is damaged and leaks or has a low (zero) voltage.
The lithium battery protection circuit board has the battery overcharge protection function, overdischarge protection function, overcurrent protection function, short circuit protection function, temperature protection function, charge power balance management function, etc. In order to prevent the battery from overcharging and over-discharging, the battery generally needs to be installed with a protection circuit board to protect the stable performance of the battery.