When the battery cell is discharged through the external load, the voltage of the battery cell will slowly decrease, and the internal DW01 will monitor the voltage of the battery cell in real time through the R1 resistor. When the voltage of the battery cell drops to about 2.3V, DW01 will consider the voltage of the battery cell to be in the state of overdischarge voltage, and immediately disconnect the output voltage of the first pin, so that the voltage of the first pin will become 0V. Switch tube in 8205A closed due to no voltage at pin 5.
At this time, the B- of the battery cell is disconnected from the P- of the protection plate. That is, the discharge circuit of the battery is cut off, and the battery will stop discharging. The protection board is in the overdischarge state and remains there.
After the P and P- of the protection board are indirectly charged, DW01 immediately stops the overdischarge state after B- detects the charging voltage, and outputs high voltage again in the first pin to make the overdischarge control tube in 8205A open, that is, the B- of the battery and the P- of the protection board are reconnected, and the battery is directly charged by the charger.