Abstract: A string trimmer includes a handle unit including a handle unit housing that defines a grip portion and a battery receptacle. The string trimmer also includes a head unit including a head unit housing, an electric motor, and a rotatable trimmer head. The string trimmer further includes a shaft assembly coupling the handle unit to the head unit. The string trimmer also includes a circuit board assembly supported within the head unit housing. The circuit board assembly includes a heat sink and a circuit board that comprises a controller configured to control the electric motor.

Abstract: A method of switching between groups of battery packs for supplying power to a power tool includes connecting a first group of battery packs and a second group of battery packs to a battery pack interface, discharging the first group to supply power to the power tool, and determining, using an electronic controller, a first condition of the first group. The method also includes discharging the second group to supply power to the power tool based on the first condition, determining, via the electronic controller, a second condition of the second group, determining, via the electronic controller, whether the first group has reached end of discharge, and discharging, in response to determining that the first group has not reached end of discharge, the first group based on the second condition.

Abstract: A string trimmer includes a handle unit including a handle unit housing that defines a grip portion and a battery receptacle. The string trimmer also includes a head unit including a head unit housing, an electric motor, and a rotatable trimmer head. The string trimmer further includes a shaft assembly coupling the handle unit to the head unit. The string trimmer also includes a circuit board assembly supported within the head unit housing. The circuit board assembly includes a heat sink and a circuit board that comprises a controller configured to control the electric motor.