What is the meaning of “0.2C charge & discharge”?

In a battery system, “0.2C charge & discharge” means charging and discharging at a rate of 0.2 times the battery's capacity. “C” is a unit multiple for battery capacity. 1C indicates charging and discharging with a current equal to the numerical value of the battery's capacity. For example, if a battery has a capacity of 1000 milliampere-hours (mAh), then a 1C charging current is 1000 milliamperes (mA), and a 1C discharging current is also 1000 milliamperes. When it comes to 0.2C, for the aforementioned 1000mAh battery, the charging current at 0.2C is 0.2 × 1000 = 200 milliamperes (mA), and the discharging current is also 200 milliamperes. This description of charging and discharging at a specific multiple is usually used to evaluate aspects such as battery performance, lifespan, and charge-discharge speed. Charging and discharging at a lower multiple is generally more beneficial for battery lifespan but may take a longer time to complete the charge-discharge process.