Analysis of the relationship and function of lithium battery protection board and lithium battery
In the mobile phone lithium battery industry, the professional name for the mobile phone lithium battery protection board is BMS. The mobile phone lithium battery protection board is composed of electronic components and pcb. It mainly plays a role in charging and discharging the mobile phone lithium battery, which is equivalent to a battery management system. When the mobile phone is fully charged, the mobile phone lithium battery protection board can ensure that the voltage difference of the battery is less than the set value, realize the balanced charging of the battery, and improve the charging effect of the battery. It can also detect battery status, such as overvoltage, overcurrent, overtemperature, undervoltage, short circuit, etc., to extend battery life and avoid battery damage due to overcharge and overdischarge.
The finished mobile phone lithium battery is composed of two parts: the battery cell and the battery protection board. The battery cell is the power storage part, which determines the quality of the mobile phone lithium battery. The battery protection board is used to protect the lithium battery from overcharge, overcurrent, and However, the two are indispensable for the release and the non-short circuit.
Due to the characteristics of the mobile phone lithium battery, it is determined that a protection board with a sampling resistor and a current fuse must appear in the lithium battery component. In normal use, the mobile phone lithium battery is undergoing a positive chemical reaction that converts electrical energy and chemical energy. When the battery is overcharged, overdischarged, or overcurrent, a chemical side reaction may occur inside the battery. When the side reaction exceeds After the positive reaction, the performance and service life of the battery will be severely affected. Therefore, there must be a battery protection board inside the mobile phone lithium battery to monitor the battery status.
The mobile phone lithium battery protection board is composed of protection IC, pcb, capacitor, resistor, diode, triode and MOS tube. The protection IC is the core device in the mobile phone lithium battery protection board, which can control the MOS tube switch in time to protect the performance of the mobile phone lithium battery. The working mechanism of the mobile phone lithium battery protection board is as follows:
Overcharge protection: When the voltage of the battery pack is greater than the maximum value and reaches the protection delay, the protection IC controls the CMOS to turn off the charging circuit.
Over-discharge protection: When the battery pack voltage is less than the maximum value and reaches the protection delay, the protection IC controls the CMOS to turn off the discharge circuit.
Over-current and short-circuit protection: When the output current of the battery pack P+ and P- exceeds the over-current/short-circuit current value and reaches the over-current/short-circuit delay, the control circuit controls the discharge CMOS to turn off the discharge circuit and stop the discharge.
High and low temperature protection: When the temperature sensor reaches the temperature threshold and the protection delay is reached, the control circuit controls to turn off the MOS tube to stop charging and discharging.
The mobile phone lithium battery protection board can also detect power, display battery working status and battery remaining capacity. In addition, there are different classification methods for mobile phone lithium battery protection boards, which can be divided into:
1. Material: Mobile phone lithium battery protection board is divided into five basic boards: hard board, soft board, single-layer board, double-layer board, and multi-layer board, among which hard board is the most commonly used one.
2. Combination: According to the different series and parallel modes of mobile phone lithium battery, the mobile phone lithium battery protection board can be divided into two types: series and parallel. Connecting lithium batteries in series can increase the overall voltage of the battery, and connecting lithium batteries in parallel can increase the overall capacity of the battery.
3. Function: According to the charging and discharging function of mobile phone lithium battery, the mobile phone lithium battery protection board can be divided into single function and two-way function. One-way means that only overcharge protection or over-discharge protection is performed on the battery, and two-way means that the protection board can have both overcharge and overdischarge functions at the same time. The two-way mobile phone lithium battery protection board is more widely used.