When the battery is divided, the data of each detection point is obtained through computer management, and the data such as the size and internal resistance of the battery capacity are analyzed to determine the quality level of the battery. This process is to divide the volume. After the battery is first divided, it needs to be allowed to stand for a period of time, generally not less than 15 days. During this period, some internal quality problems will be manifested.
For example, the self-discharge is too large, the internal resistance becomes large, and so on. After the end of the rest period, the test is again performed, the capacity is not up to grade, and the quality problem is eliminated. Another purpose of the volumetric separation is to classify the battery by combining the monomers with the same internal resistance and the same capacity.
When combined, only the performance is very close to form a battery pack. For example, in order to meet the energy needs of electric vehicles, power battery packs often need dozens to thousands of batteries. Due to the complexity of the system, the behavior of the battery pack is unique. It is not a simple operation of the single battery. The addition and subtraction method can obtain the performance of the battery pack.
Take our common series and parallel battery packs as an example. Ideally, the cells in all battery packs should be identical, but in fact even the same batch of cells produced in the same batch still have performance differences ( Including factors such as capacity and internal resistance).
Although screening is performed before the battery pack is formed, it is impossible to ensure that all the battery performances are 100% consistent. In addition, due to the volume of the battery pack, the heat dissipation characteristics of different portions are also different, so the battery pack also has a large temperature distribution. Temperature gradient.
All of the above factors may cause the speed of the battery in the battery pack to be inconsistent during use. In this case, the available capacity of the battery pack is reduced on the one hand (limited by the minimum capacity of the series battery in the battery pack).
On the other hand, it may also cause the battery pack to be less safe. Studies have shown that even if the cycle life of a single battery can reach more than 1000 times, in the battery pack, if there is no protection of the equalization equipment, the cycle life of the battery pack may be less than 200 times, so for the battery pack, the unit battery is consistent. Sex is a very important parameter.