A biopsy driver assembly (12) includes a biopsy driver housing (24). An electrical assembly (200) is coupled to the biopsy driver housing. The electrical assembly includes at least one electrical drive (361,362) configured for drivably engaging a biopsy probe assembly. A battery (34) is coupled to the biopsy driver housing. A control circuit (702) is coupled to the biopsy driver housing. The control circuit is electrically coupled to the battery and to the electrical assembly (700). The control circuit has a motion detector (704), a timer circuit (706) and a battery dwell circuit (708). The control circuit is configured to conserve the battery by providing electrical power only to the motion detector after a predetermined time following a last detected physical movement of the biopsy driver assembly and to provide electrical power from the battery also to the electrical assembly when a physical movement of the biopsy driver assembly is detected.
