Battery pack and cordless tool using the same

摘要

A battery device is constituted by connecting such cell assemblies in parallel as each includes: a first cell group having a plurality of cells connected in series; a housing container for housing the first cell group; current detector housed in the container for detecting a current to flow through the first cell group; a switching element connected with the first cell group for turning ON/OFF the current to flow through the first cell group; and a controller for controlling the ON/OFF of the switching element in response to the output signal of the current detector.