US Patent 10084330 Battery pack and charger

A battery pack includes a secondary battery, a connector that can be detachably connected to multiple different types of devices, control circuitry that controls power supply from the secondary battery and charge of the secondary battery, a detector that outputs the detected state of the secondary battery as secondary battery information, a first memory that stores the secondary battery information, a second memory that stores a recommendation table in which each of multiple conditions predetermined for the state of the secondary battery and a recommended device are associated with each other, a determiner that determines a recommended device from among the devices using the secondary battery information and recommendation table, and an informer that reports information indicating the recommended device determined by the determiner to the user.