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What is the working principle of the battery protection board? What is it for?

The battery protection board is a lithium-ion battery protection board. It is an integrated circuit board for rechargeable (generally referred to as lithium-ion batteries) for protection purposes. The reason why lithium ion batteries (rechargeable) need to be protected is determined by their own characteristics. Since the material of the lithium-ion battery itself determines that it cannot be overcharged, over-discharged, over-current, short-circuited, and ultra-high temperature charging and discharging, the lithium-ion battery components will always appear with a protection board with a sampling resistor and a current fuse .

The protection board usually includes control IC, MOS switch, JEPSUN precision resistor and auxiliary device NTC, ID memory, PCB, etc. Among them, the control IC controls the MOS switch to turn on under all normal conditions to make the cell communicate with the external circuit. When the cell voltage or loop current exceeds the specified value, it immediately controls the MOS switch to turn off (tens of milliseconds). Protect the safety of batteries.

The working principle of the battery protection board and its purpose

The normal working process of the lithium-ion battery protection board is: when the battery cell voltage is between 2.5V and 4.3V, the first and third pins of DW01 both output high level (equal to the supply voltage), and the second pin voltage is 0V. At this time, the voltage of pin 1 and pin 3 of DW01 will be applied to pins 5 and 4 of 8205A respectively. The two electronic switches in 8205A are in the conducting state because their G poles are connected to the voltage from DW01, that is Both electronic switches are in the open state. At this time, the negative pole of the battery is directly connected to the P- terminal of the protection board, and the protection board has voltage output.


1. Voltage protection: overcharge and overdischarge

2. Current protection: It is mainly reflected in the operating current and overcurrent to disconnect the switch MOS to protect the battery pack or load.

3. Short-circuit protection: Strictly speaking, it is a voltage-comparative type of protection, that is, it is directly turned off or driven by voltage comparison, and does not go through extra processing.

4. Temperature protection: generally used in smart batteries, it is also indispensable.

5. MOS protection: the important thing is MOS voltage, current and temperature.

6. Self-power consumption, this parameter is as small as possible, the most ideal state is zero, but it is impossible to achieve this.

7. Equalization: At present, the most common equalization methods are divided into two types, one is energy consumption, and the other is energy conversion.

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