There are three main states of lithium batteries, one is the working discharge state, one is to stop working charging state, and the last is the state of storage, these states will lead to the problem of power difference between the cells of the lithium battery pack, and the power difference is too large and too long, it will seriously affect the service life of the battery, so the lithium battery protection plate is needed to take the initiative to do the balance of the battery cells.
Solution of active balancing method for charging Li-ion battery pack:
Active balancing discards the method of passive balancing that consumes current in favor of a method that transfers current. The device responsible for charge transfer is a power converter that enables the small cells within a lithium-ion battery pack to transfer charge whether they are charged, discharged or idle, so that dynamic balancing between the small cells can be maintained on a regular basis.
Since the active balancing method is extremely efficient in charge transfer, a higher balancing current can be supplied, which means that this method is more capable of balancing the Li-ion battery pack during charging, discharging and idling.
The active balancing function allows each small cell in the Li-ion battery pack to be balanced faster, so the fast charging is safer and suitable for higher current and higher rate charging methods.
Even if each small cell has reached the equilibrium state when charging, but due to the different temperature gradient, some small cells have higher internal temperature, some small cells have lower internal temperature, but also make the internal leakage rate of each small cell is different, test data shows that the leakage rate doubles for every 10 ℃ increase in the battery, the active balancing function can ensure that the small cells in the idle Li-ion battery pack constantly regain equilibrium, which is conducive to the battery pack stored power can be fully utilized, so that when the battery pack work capacity ends, the individual small Li-ion battery residual power minimum.
There is no lithium-ion battery pack with 100% discharge capacity. This is because the end of the working capacity of a group of lithium-ion batteries is determined by one of the first small lithium-ion batteries to be discharged, and there is no guarantee that all small lithium-ion batteries will reach their discharge capacity at the same time. Instead, there will be individual small Li-ion cells that will maintain unused residual power. With the active balancing method, when a Li-ion battery pack is discharged, the large-capacity Li-ion battery inside distributes the power to the small-capacity Li-ion battery, so that the small-capacity Li-ion battery can also be fully discharged, and there is no residual power left in the battery pack, and a battery pack with active balancing has a larger actual power storage (i.e., it can release power closer to the nominal capacity).
Post time: Aug-23-2022