SURGICAL TOOL WITH AN ASEPTIC POWER MODULE THAT ENTERS A SPECIFIC OPERATING STATE BASED ON THE TYPE OF HANDPIECE TO WHICH THE MODULE IS ATTACHED

A surgical handpiece (40) including a shell (42) is disclosed. The shell is shaped to define a void (52) for receiving a power module (180) and an opening through which the power module is insertable into and removable from the void space. A lid (62) is moveably mountable to the shell to cover the shell opening, and a latch (90, 101) moveably attached to one of the shell or the lid for holding said lid in a latched state. A data tag (98) is mounted to the latch (90, 101) so as to move with said latch. The data tag (98) includes data that identifies said handpiece. A power module for the handpiece, comprising: a shell (180) with a tower (210) with a cross sectional area less than that of the base (182); a motor (290) in said shell tower; a cell/battery (270) in said shell base; a first set of sensors (286, 288) in said shell base and a second set of sensors (302, 304) in said shell tower spaced at least 5 cm apart from the first set, for detecting magnetic fields generated external to said shell; a controller (320) to regulate the application of current from the cell to said motor to control the actuation of said motor based on the received sensor signals.