Currently, there are two main types of balanced multi-series lithium-ion battery systems on the market: traditional passive balancing and active balancing. There is some debate regarding whether lithium-ion battery pack protection boards should include balancing functionality. Below is a perspective from a lithium-ion battery manufacturer.
1. Situations where balancing is necessary: When lithium-ion battery packs are manufactured and stored for a long time, the voltage of each string of batteries in the entire battery pack becomes inconsistent due to the different static power consumption of each circuit of the protection board and the different self-discharge rates of each cell. This results in a significant voltage difference. However, while ensuring consistent capacity, balancing can balance the voltage of the lithium-ion battery pack, thereby achieving the effect of full charging and full discharging of the battery pack and maximizing its performance.
2. The balancing function is not effective: Many people believe that balancing is useful in the middle and later stages of lithium-ion battery pack use. In fact, in the middle and later stages of battery pack use, due to the different capacity loss of each cell, a capacity difference is caused. The balancing function of the protection board cannot make up for the cell capacity. Therefore, we should understand that the lithium-ion battery protection board balances voltage, but cannot make up for the capacity.
For lithium-ion battery packs with 13 or fewer cells, it is recommended to omit the balancing function. However, strict control over battery matching is essential to ensure consistency in cell capacity and internal resistance. Lithium-ion batteries are susceptible to damage during storage, but not during use! Individual lithium-ion batteries are better stored than entire packs. Once a battery pack is assembled, it should be tested and delivered to the consumer as soon as possible.
When charging a series of lithium-ion batteries, it is essential to ensure that each cell is charged evenly; otherwise, the performance and lifespan of the entire battery pack will be affected during use. Commonly used equalization charging techniques include constant shunt resistor equalization charging, on-off shunt resistor equalization charging, uniform battery voltage equalization charging, switched capacitor equalization charging, buck converter equalization charging, and inductor equalization charging.
