Active balancing abandons the passive balancing method that consumes current, and instead uses a method that transfers current. The device responsible for charge transfer is a power converter, which enables the small cells in the lithium-ion battery pack to transfer charge whether they are charging, discharging, or idle, thus allowing the small cells to maintain a dynamic balance at all times.
Because the active balancing method has extremely high charge transfer efficiency, it can supply a higher balancing current, which means that this method has a stronger balancing capability when lithium-ion battery packs are charging, discharging and idle.
1. Strong fast charging capability: The active balancing function can make the small cells in the lithium-ion battery pack reach balance more quickly. Therefore, fast charging is safer and suitable for high-rate charging with larger current.
2. When idle: Even if each small battery has reached the equilibrium state it was in when charging, due to different temperature gradients, some small batteries have higher internal temperatures and some have lower internal temperatures, which will cause the leakage rate of each small battery to be different. Test data shows that for every 10°C increase in battery temperature, the leakage rate doubles. The active balancing function can ensure that the small batteries in the idle lithium-ion battery pack are constantly rebalanced. This is conducive to the full utilization of the energy stored in the battery pack, so that when the battery pack is no longer in operation, the residual energy of each small lithium-ion battery is minimized.
3. During discharge: No lithium-ion battery pack can discharge to 100% capacity. This is because the end of the working capacity of a lithium-ion battery pack is determined by the first small lithium-ion battery to discharge completely, and it cannot be guaranteed that all small lithium-ion batteries will reach full discharge simultaneously. On the contrary, some small lithium-ion batteries will retain unused residual energy. Through active balancing, during discharge, the large-capacity lithium-ion batteries in the lithium-ion battery pack will distribute energy to the small-capacity lithium-ion batteries. Therefore, the small-capacity lithium-ion batteries can also be fully discharged, and no residual energy will remain in the battery pack. Battery packs with active balancing function have a larger actual storage capacity (i.e., they can release energy closer to the nominal capacity).
