1. Lithium ion battery protection board

When the voltage of the battery cell is between 2.5V and 4.3V, the first and third pins of DW01 both output a high level (equal to the supply voltage), and the voltage of the second pin is 0V. At this time, the voltage of the first and third pins of DW01 will be applied to the fifth and fourth pins of 8205A, respectively. The two electronic switches inside 8205A are in a conductive state because their G pole is connected to the voltage from DW01, that is, both electronic switches are in an open state. At this point, the negative pole of the battery cell is directly connected to the P-terminal of the protection plate, and the protection plate has a voltage output.

2. Protection board for overcharging protection

When the battery is charged normally through the charger, as the charging time increases, the voltage of the battery cell will become higher and higher. When the voltage of the battery cell rises to 4.4V, DW01 will consider that the voltage of the battery cell is in an overcharged voltage state, and immediately disconnect the output voltage of the third pin, causing the voltage of the third pin to become 0V. The switch tube in 8205A will close due to the lack of voltage on the fourth pin. At this time, the B - of the battery cell and the P - of the protection board are in a disconnected state. If the charging circuit of the battery cell is cut off, the battery cell will stop charging. The protective board is in an overcharged state and has been maintained continuously.

After the P and P - of the protection board discharge the load indirectly, although the overcharge control switch tube is closed, the positive direction of the internal diode is the same as the direction of the discharge circuit, so the discharge circuit can be discharged. When the voltage of the battery cell is placed below 4.3V, DW01 stops the overcharge protection state and outputs a high voltage at pin 3, making the overcharge control tube in 8205A conductive, that is, electrified

3. Protection board over discharge protection control

When the battery cell is discharged through an external load, the voltage of the battery cell will gradually decrease. At the same time, 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 that the voltage of the battery cell is in an over discharge voltage state, and immediately disconnect the output voltage of the first pin, causing the voltage of the first pin to become 0V. The switch tube inside 8205A will close due to the lack of voltage on the fifth pin. At this time, the B - of the battery cell and the P - of the protection board are in a disconnected state

The lithium-ion battery protection board is in an over discharge state and has been maintained continuously. After the P and P - of the protection board are indirectly charged with voltage, DW01 immediately stops the over discharge state after detecting the charging voltage through B -, and outputs a high voltage again on pin 1 to conduct the over discharge control tube in 8205A. That is, the B - of the battery cell is reconnected with the P - of the protection board, and the battery cell is directly charged through the charger.

The B - of the core and the P - of the protection board are reconnected, and the battery cell can resume normal charging and discharging.

Shenzhen Topband Battery Co., Ltd.，established in 2006, is a wholly-owned subsidiary of Shenzhen Topband Co., Ltd. (002139.SZ). We focus on lithium iron phosphate batteries,with independent research and development in cells and BMS. With the ability to integrate the entire industry chain, we are committed to providing customers with one-stop lithium battery solutions and services. Our quality products are widely used in energy storage and light power.