An under-floor charging station can be mounted under a floor such that a top plate of the under-floor charging station is substantially flush with a top surface of the floor without touching the ground. Openings in the top plate allow charging elements to extend when in use to charge a mobile robot, and to retract under the floor when not in use. The retractable charging elements prevent tripping hazards and allow the mobile robot to move freely throughout a clean room. Moreover, because the charging elements can be retracted in an unobtrusive position when the under-floor charging station is not in use, the under-floor charging station is permitted to be positioned in locations in the clean room that allow the mobile robot to continue working while charging and/or allow non-stop running of the mobile robot.