How to control the customized charging and discharging process of 18650 lithium batteries?3.7V 18650 lifepo4 battery

　　The charging control of lithium batteries is divided into two stages. The first stage is constant current charging, and when the battery voltage is below 4.2V, the charger will charge at a constant current. The second stage is the constant voltage charging stage. When the battery voltage reaches 4.2V, due to the characteristics of the lithium battery, if the voltage is higher, it will be damaged. The charger will fix the voltage at 4.2V, and the charging current will gradually decrease. When the current decreases to a certain value (usually 1/10 of the current setting), the charging circuit will be cut off, and the charging completion indicator light will be on, indicating that the charging is completed.

　　Excessive charging and discharging of lithium-ion batteries can cause permanent damage to the positive and negative electrodes. Excessive discharge leads to the collapse of the negative electrode carbon layer structure, which can cause lithium ions to be unable to be inserted during the charging process; Overcharging causes excessive lithium ions to be embedded in the negative carbon structure, causing some of the lithium ions to no longer be released.

　　Some chargers are implemented using inexpensive solutions, but their control accuracy is not good enough, which can easily cause abnormal battery charging and even damage the battery. When choosing a charger, try to choose a large brand 18650 lithium-ion battery charger, with guaranteed quality and after-sales service to extend the battery's service life.

　　The 18650 lithium-ion battery charger guaranteed by the brand has four protections:

　　Short circuit protection, overcurrent protection, overvoltage protection, battery reverse connection protection functions, etc.

　　Overcharge protection: When the charger overcharges a lithium-ion battery, to prevent internal pressure rise caused by temperature rise, the charging state needs to be terminated. For this purpose, the protective device needs to monitor the battery voltage. When it reaches the overcharging voltage of the battery, the overcharging protection function is activated and charging is suspended.

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