A compact battery powered mover for heavy rollable loads, having a ventilated battery compartment incorporated into the body of the mover and a removable rechargeable ventilated battery that permits the replacement of a spent battery with a fresh battery at the work location. The optical signal emitted from the opto-electronic device array reflects by the reflecting slope and is incident into the inclined plane of the micro-lens array plate with the specific angle. The method provides for determining a desired rotary actuator center-of-gravity location for locating the installed HSA portion center-of-gravity along the pivot axis for mitigating acceleration of the rotary actuator about the pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation.