During the constant current charging and discharging process, the voltage is not constant.
In the constant current charging, the voltage changes are: rising, steady, rising (can not be recharged when rising to a certain extent, recharge may call the charging may explode)
In the case of constant current discharge, the voltage change is: falling, smooth, and falling (the voltage is getting lower and lower, which is well understood? If it drops to a certain level, it will be out of power)
It can be seen that during constant current charging and discharging, the voltage has a smooth process, and this stationary value is the charging and discharging platform.
Of course, the stationary value is not an absolute level, but the more horizontal the better, and the longer the better. Because the battery is to use the period of steady voltage, not the period of constant voltage change.