When the cell voltage is between 2.5V and 4.3V, the first pin and the third pin of DW01 output a high level (equal to the supply voltage), and the second pin voltage is 0V. At this time, the voltage of the first and third pins of DW01 will be added to the fifth and fourth pins of 8810 respectively. The two electronic switches in 8810 are in the on-state because their G poles are connected to the voltage from DW01, that is, the two electronic switches are in the on state. At this time, the negative electrode of the battery cell is directly connected to the P-end of the maintenance board, and the maintenance board has a voltage output.