The 3.2V of the lithium iron phosphate battery pack is the rated voltage. During the charging process, the full-charge voltage is related to the charging current. When the current is 0.3C, 3.8V can be judged as full. If it is 0.1C, it can be considered as full when it is charged to 3.65V.
It is recommended to use the CCCV charging method for charging the lithium iron phosphate battery pack, that is, first constant current and then constant voltage. The recommended constant current is 0.3C, and constant voltage is 3.65C. That is, 0.3C current charge in the constant current process, when the battery voltage reaches 3.65V, use 3.65V voltage constant voltage charge, when the charging current is lower than 0.1C (or 0.05C), stop charging, that is, the battery is already full. When you charge with a constant voltage power supply, you also need to look at the charging current. It is recommended not to charge with too high a voltage. After adjusting the voltage, ensure that the charging current is below 0.5C, which is good for the battery.
We know that the lithium battery packs need to be charged with a matching charger. In the industrial supporting market, since each product is packaged separately and is not compatible with each other, the corresponding charger should be selected according to the lithium battery pack used and charged in strict accordance with the requirements. Regardless of the industrial or civilian market, the basic principles of how to charge li ion batteries for sale are the same. Therefore, the steps and standards for charging lithium batteries can be regulated. Generally, the nominal voltage of lithium batteries is 3.7V. The voltage is 4.2V.
(1) Constant voltage charging method: During the charging process, the output voltage of the charging power supply remains constant. As the state of charge of the lithium ion power pack changes, the charging current is automatically adjusted. If the prescribed voltage is constant, it can not only ensure the full charge of the power battery, but also minimize air leakage and water loss. This charging method only considers the change of the battery voltage in a single state, and cannot effectively reflect the overall charging status of the battery. Its initial charging current is too large, often causing damage to the power battery. In view of this shortcoming, constant voltage charging is rarely used.
(2) Constant current charging method: During the entire charging process, the charging current is kept constant by adjusting the output voltage. Keep the charging current constant, the charging rate is relatively low. The constant current charging control method is simple, but because the acceptable current capacity of the lithium battery pack gradually decreases with the progress of the charging process, in the later stage of charging, the power battery receiving capacity decreases, and the charging current utilization rate is greatly reduced. The advantages of this method are simple, convenient, and easy to implement, and the charging power is easy to calculate.
(3) Constant current and constant voltage charging method: This charging method is a simple combination of the above two. The constant current charging method is used in the first stage to avoid excessive charging current at the beginning of constant voltage charging. The second stage adopts the constant voltage charging method to avoid the phenomenon of overcharging during constant current charging. Lithium iron phosphate battery packs are the same as any other sealed rechargeable batteries. The charging must be controlled, and excessive charging is not allowed, otherwise the battery will be easily damaged. Lithium iron phosphate batteries generally adopt a charging method of constant current first and then voltage limiting.