Detailed Explanation of Lithium-ion Battery Protection Circuits and the Principle of Lithium-ion Battery Protection Boards. The principle of lithium-ion battery protection boards is very simple. The reason why rechargeable lithium-ion batteries need protection is determined by their inherent characteristics. Due to the materials used in lithium-ion batteries, they cannot be overcharged, over-discharged, overcurrented, short-circuited, or charged and discharged at excessively high temperatures.
Detailed Explanation of Lithium-ion Battery Protection Circuit
Due to the chemical characteristics of lithium-ion batteries, during normal use, positive chemical reactions occur inside the battery, converting electrical energy into chemical energy. However, under certain conditions, such as overcharging, over-discharging, and overcurrent, side chemical reactions can occur inside the battery. If these side reactions intensify, they can seriously affect the battery's performance and lifespan, and may also produce a large amount of gas, causing the internal pressure of the battery to increase rapidly and eventually explode, leading to safety issues.
Therefore, all lithium-ion batteries require a protection circuit to effectively monitor the battery's charging and discharging status and, under certain conditions, shut down the charging and discharging circuits to prevent damage to the battery.
To ensure safety during use, lithium-ion batteries must be equipped with appropriate battery management circuits to prevent overcharging, over-discharging, and overcurrent. The ultra-small package and minimal external component requirements of lithium-ion battery protection ICs have made them widely used in the design of single-cell lithium-ion battery protection circuits.
Currently, dedicated lithium-ion battery protection board testers have appeared on the market, but they are generally expensive, and the IC must be soldered onto the circuit board before testing.
In practical applications, the most important parameters of lithium-ion battery protection ICs that customers value most are: overcharge, over-discharge and overcurrent protection voltages, quiescent operating current and power-off current, overcharge, over-discharge and overcurrent protection delays, and the high and low levels of the OD and OC pins.
Lithium-ion battery protection board principle
Commonly used equalization charging techniques for lithium-ion battery protection boards include constant shunt resistor equalization charging, on/off shunt resistor equalization charging, average battery voltage equalization charging, switched capacitor equalization charging, buck converter equalization charging, and inductor equalization charging.
Lithium-ion battery protection boards also protect the battery from overcharging. When an external power source continuously and rapidly charges the battery, the protection board activates its protective function. When the internal charge of the lithium-ion battery reaches saturation, the internal circuitry of the protection board automatically cuts off the external fast-charging power, preventing external power from entering the battery. This is precisely the principle behind how lithium-ion battery protection boards protect against overcharging.
