Under the conditions specified by the design (such as temperature, discharge rate, termination voltage, etc.), the minimum capacity that the battery should be able to discharge, in amps per hour, is indicated by the symbol C. The capacity is greatly affected by the discharge rate, so the discharge rate is often indicated by Arabic numerals in the lower right corner of the letter C, such as C20 = 50, indicating a capacity of 50 amps per hour at a 20 o'clock rate. The theoretical capacity of the battery can be accurately determined from the amount of the electrode active material in the battery reaction formula and the electrochemical equivalent of the active material calculated according to Faraday's law. Due to the side reactions that may occur in the battery and the special needs of the design, the actual capacity of the battery is often lower than the theoretical capacity.