In an effort to better compare and contrast various lithium cell and battery chemical composition attributes, lithium chemistries are given a standard method of designating their discharge rate capabilities known as a “C Rate.” The C Rate (or as it is known in technical publications, It) is an equivalent discharge rate in amperage that is based on the value of the cell or battery’s rated capacity and is expressed as a multiple of that rated capacity. In this context, the “C” stands for “capacity.”
The C Rate can also be used to designate at what rate the cell or battery has or will be discharged at, e.g. “discharge the battery at a 0.2C rate until the voltage reaches 10V.” In this case, the battery would be discharged at whatever amperage would complete the discharge in five hours. There is no such thing as an “E Rate” to express capabilities or discharge requirements in terms of wattage. Generally users choose a constant power rate of discharge that is mathematically similar to the desired C Rate.
