A cordless system has cordless system components that include a cordless device, such as a cordless power tool, a battery pack and a charger. The battery pack is mated with either the cordless device to provide power to operate the cordless device or to the charger to charge the battery cells in the battery pack. In an aspect, the cordless system has an identification and communication system by which the battery pack identifies and communicates information about the battery pack to the cordless device or to the charger to which the battery pack is mated. In an, the battery pack of the cordless system is capable of multiple modes, such as controlling the cordless device and controlling the charger. In an aspect, the battery pack validates the cordless device or charger to which it is mated. in an aspect of the invention, the cordless system uses any of a wired interface, radio frequency interface, an optical interface or a magnetic interface to communicate information between the battery pack and the cordless device or charger to which the battery pack is mated. In an aspect, female terminals are used in a terminal block of the battery pack to protect against foreign objects contacting the terminals. In aspect, the terminals in the terminal block of the battery pack are staggered or scattered to reduce the likelihood of a short circuit. In an aspect of the invention, the battery pack has a trap door that closes when the battery pack is not mated to a cordless device or charger to protect the terminal block of the battery pack. In an aspect of the invention, multi-spring, split contact terminals are used in the terminal block of at least one of the cordless system components. In an aspect of the invention, the battery cells are Lithium Ion battery cells.