Researchers at Ecole Polytechnic in Lausanne have developed marXbot and snazzy battery exchange system. The batteries are modular and charge in a kind of ferris-wheel. When the robot runs low on juice, it docks with the station, and the dead battery is removed from the robot chassis by a manipulator. During the swap, robot power is provided by an alternate ultra-capacitor based system that can provide 15 seconds of power for the critical systems (i.e. only maintaining cpu memory state). The wheel rotates to a fresh battery, and the manipulator pushes it into the chassis, completing the hot-swap.