Requirements for fast-charging lithium-ion batteries
●Based on the structural characteristics of fast-charging lithium-ion batteries, the maximum charging termination voltage should be 4.2V. Overcharging is not allowed, otherwise too many lithium ions will be removed from the positive electrode, rendering the battery unusable.
● Lithium-ion batteries have high charging and discharging requirements and can be charged using a dedicated constant current and constant voltage charger. Typically, constant current charging is performed until 4.2V per cell, then constant voltage charging is switched to. Charging should be stopped when the constant voltage charging current drops below 100mA.
● Charging current (mA) = 0.1 to 1.5 times the battery capacity (e.g., for a 2000mAh battery, the charging current can be controlled between 200 and 4000mA). A typical charging current can be selected at around 0.5 times the battery capacity, with a charging time of approximately 2 to 3 hours.
How much impact does fast charging have on lithium-ion batteries?
Whether a lithium-ion battery can be fast-charged depends on the manufacturer's experimental data. Not all lithium-ion batteries can be fast-charged; otherwise, their lifespan would be significantly reduced, and there would be risks such as fire and explosion. Therefore, manufacturers configure slow-charging and fast-charging ports according to the characteristics of lithium-ion batteries, and the charging process is managed uniformly by the BMS system. As long as the charging is done according to the manufacturer's requirements, it is safe.
Lithium-ion batteries and lead-acid batteries operate on the same principle. Fast charging works by first increasing the voltage, and then increasing the current. Because fast charging uses this principle, the large current causes the battery to overheat and react rapidly. This reaction generates a lot of heat, which, due to internal resistance and exceeding temperature limits, can damage or prematurely age the battery.
Lithium-ion batteries do not have a charge memory. The so-called nominal number of charge cycles is 500. This means that it can be charged from 0% to 100% 500 times.
Strictly speaking, any fast charging will damage the battery. However, if the lithium-ion battery density, materials, temperature, and battery management system of an electric vehicle are designed very reasonably, then this damage will be within a reasonable range, or simply put, it will not damage the battery.
