Patent ID: 8752645

Claim:
A charge device for charging a battery pack that is comprised of a plurality of connected cells, the charge device comprising: a control unit for controlling a charging process of a connected battery pack, wherein said control unit is arranged in a housing of a power tool and wherein said battery pack is an energy supply that supplies energy for a drive motor of the power tool and said control unit through a connecting line; wherein said battery pack has a monitoring circuit for detecting operating parameters of said cells selected from charged state, cell voltage, cell current, cell temperature, and others; a communication line between said control unit and said monitoring circuit, wherein at a communication voltage level digital data are exchanged between said control unit and said monitoring circuit; a controller for controlling data traffic through a sending unit and a receiving unit; wherein a communication voltage tapped at said communication line is higher than a permissible input voltage level of said controller and lower than a maximum battery pack voltage; wherein said receiving unit, as a filter, converts a received first signal level that is lower than a first voltage to a LOW signal and lowers a received second signal level that is higher than a second voltage to said input voltage level of said controller and relays said second signal level as a HIGH signal; wherein said communication voltage is in a range of 10 volt to 25 volt.