Li-ion battery charging precautions and process

Lithium-ion battery charging-precautions Note 1: Prevent the temperature from being too high during charging. If the temperature during charging is higher than the specified operating temperature (35°C), the power of the lithium-ion battery will continue to decrease, that is, the power supply time under full charge Shortening will cause damage to battery quality and reduce battery life. Note 2: Prevent the temperature from being too low during charging. If the battery is in a low temperature environment (below 4°C) during charging, the battery's power will continue to decrease, or even fail to charge, but the situation is different from the high temperature environment. It is not permanent damage. When the temperature rises to an appropriate level, the battery power will return to its previous state. Note 3: Frequent use will make the electrons in the lithium-ion battery always flow, which is conducive to the extension of its life. If you don't use it often, remember to complete a charge cycle for the lithium-ion battery every month, that is, deep discharge and deep charge once. Lithium-ion battery charging process The most suitable charging process for lithium-ion batteries can be divided into four stages: trickle charge, constant current charge, constant voltage charge, and charge termination. Refer to Figure 1. Lithium-ion battery charging method_Lithium-ion battery charging process stage 1: trickle charge Trickle charge is used to pre-charge the fully discharged battery cell (recovery charge). When the battery voltage is lower than about 3V, first charge the battery with a constant current of maximum 0.1C. Phase 2: Constant current charging When the battery voltage rises above the trickle charge threshold, increase the charging current for constant current charging. The current for constant current charging is between 0.2C and 1.0C. The current during constant current charging is not required to be very accurate, and quasi-constant current is also acceptable. In the linear charger design, the current often rises as the battery voltage rises to minimize the heat dissipation problem on the pass transistor. Constant current charging greater than 1C will not shorten the entire charging cycle time, so this approach is not advisable. When charging with a higher current, the battery voltage will rise more quickly due to the overvoltage of the electrode reaction and the voltage rise on the internal impedance of the battery. The constant current charging phase will be shorter, but since the time of the constant voltage charging phase below will be increased accordingly, the total charging cycle time will not be shortened. Phase 3: Constant voltage charging When the battery voltage rises to 4.2V, the constant current charging ends and the constant voltage charging phase begins. To maximize performance, the voltage regulation tolerance should be better than +1%. Stage 4: Charge termination is different from nickel batteries, and it is not recommended to continue trickle charging of lithium-ion batteries. Continuous trickle charging will cause the plate plating effect of metallic lithium. This will make the battery unstable and may cause a sudden automatic quick disassembly. There are two typical charging termination methods: using the minimum charging current to determine or using a timer (or a combination of the two). The minimum current method monitors the charging current in the constant voltage charging stage, and terminates the charging when the charging current decreases to the range of 0.02C to 0.07C. The second method starts timing at the beginning of the constant voltage charging phase, and terminates the charging process after two hours of continuous charging. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.