CHARGE CONTROL SCHEME FOR USE IN POWER TOOLS

摘要

A simplified control scheme is presented for use in a power tool. The power tool may be comprised of two or more lithium-ion battery cells connected in series and operable to drive the motor in the tool. A charging circuit is configured to receive a charging current from an AC adapter and to supply the charging current to the battery cells. A microcontroller monitors the voltage of the battery cells and terminates charging of the battery cells in accordance with the monitored voltages of the battery cells. The microcontroller does not receive power from the battery cells but is only powered by the AC adapter. Of note, each of the battery cells preferably employs an electrolyte composition comprised of a redox shuttle material. In combination with other tool components, the use of the redox shuttle material reduces or eliminates the need for expensive charge and discharge controls, thereby reducing the cost of the tool.