A battery torque wrench is a battery-operated torque wrench that can apply a specified torque without effort from the operator. It contains a planetary torque multiplier or a gearbox. A reaction device that absorbs the torque rather than the tool operator. The torque output is adjusted by varying the voltage on the motor. The battery torque wrench is used to remove stubborn nuts, or to apply accurate torque. The gearboxes can have multiplication ratios up to 125:1.