An AA battery is a dry cell-type battery commonly used in portable electronic devices. An AA battery is composed of a single electrochemical cell. The voltage of an AA battery is the same as a AAA battery, C cell or D cell. AA batteries, however, provide power for a longer period than AAA batteries, because their larger size allows them to store a greater mass of anode material which is consumed as it does electrical work. C and D cells, being larger, last longer still; as a rough guide, the capacity of a battery scales linearly with its mass.