Abstract: Latching components of a padlock are driven by a motor between latched and released positions. An encoder element with associated optical elements provides position information to a control circuit. The control circuit correlates the position information with the signal directing power to the motor so that the motor is precisely controlled for moving the latching elements between release and latch. If the motor jams (sensed by overcurrent), it is operated briefly in alternating directions to try and dislodge the grit or ice causing the jam. The padlock shackle is latched into place by balls which are driven into recesses in the shackle legs. The use of plural balls on at least one side helps isolate the drive motor and gears from grit that may enter through the padlock's top shackle holes.