Abstract: A single cell power unit for a motorized surgical power tool includes a single cell power unit enclosure. A high temperature battery cell is mechanically supported within and disposed at about a center of the single cell power unit enclosure. An electrical connector having a plurality of connector pins is configured to couple to a mating electrical connector of a tool part having a motor. A motorized surgical handpiece tool which prevents the motor from operating when the power unit is removed, a method to start a multi-phase brushless sensorless motor of a surgical hand piece tool in a controlled manner, a power unit for a motorized surgical power tool with a battery insulated by a flexible circuit boards, and a safety switch system for a motorized surgical power tool with a lever magnet motor speed control are also described.