What Is the Discharge Residual Capacity of the Battery?

When discharging a rechargeable battery at a high current (e.g., 1C or above), the battery reaches the terminal voltage before its capacity is fully discharged. It’s due to the “bottleneck effect” that exists in the internal diffusion rate caused by the overcurrent.

And it can still continue to discharge with a small current such as 0.2C. And when the discharge reaches 1.0V/piece (nickel-cadmium and nickel-hydrogen battery) and 3.0V/piece (lithium battery), the released capacity is called residual capacity.