The inconsistency between the single cells often causes the battery pack to have problems such as too fast capacity decay and short life during the cycle, which eventually leads to premature failure of the battery pack. Therefore, the batteries must be sorted during the process of grouping. The battery voltage, capacity, internal resistance, etc. are measured to ensure the consistency of the battery's initial performance. In the production process, automatic sorting equipment is used to automatically collect the AC internal resistance and open circuit voltage of the cells to classify the cells to improve the consistency and stability of the quality of the batteries shipped, with high automation and easy operation.