An electrical apparatus includes a body for consuming power; a battery for supplying power to the body, wherein the body is capable of detecting an installation of the battery into the body, correlating the installation of the battery to a current real-time date, and displaying the date on which the battery was first installed in the body; and a display of a full charge capacity of the battery, the full charge capacity being calculated by comparing an actual present capacity of the battery to an estimated present capacity of the battery.