Answer: The capacity of the battery refers to the amount of electricity that the active material in the battery can participate in the electrochemical reaction is called the capacity of the battery, that is, the amount of charge that the battery can hold after charging. The unit is "Ah" (Ah) and 1 A (A). The current is discharged for 1 hour, and the capacity is 1 ampere hour (Ah). Assuming that the average current is 4A, the discharge time is 3 hours when the battery is discharged at the termination voltage of the battery, and the battery capacity is 12Ah (the discharge is not calculated here) effectiveness).