Patent ID: 7928692

Claim:
An electronics module of a battery pack for powering a cordless power tool, the pack including a plurality of lithium-ion battery cells therein, the module comprising: an integrated circuit which includes a first voltage monitoring unit for monitoring individual lithium-ion cell voltages and total stack voltage of the lithium cells during charge and discharge operations; a microcontroller external to and in connection with the integrated circuit; a discharge FET for controlling one of current and power output from the battery pack to control a motor of the tool, wherein the microcontroller selectively controls the discharge FET so as to control current to the tool motor; a second voltage monitoring circuit distinct from the first voltage monitoring unit that monitors individual cell voltages and, without interfacing with the battery electronic control unit, generates a disable signal in a charge operably coupled to the battery pack when any cell reaches an over-voltage condition during a charging operation; and a fuse in a charge return line to the module.