| The Roomba Discovery comes with a charging station, two virtual wall units (which send out an infrared signal across, say, a passageway or doorway, so the Roomba will not cross the
threshold), and a wall-mount device. Its ability to charge itself when power runs out is a handy feature for big jobs, which can easily eat up all of its two hours worth of juice. In our tests, the battery lasted about that long before the Roomba looked for
its charging base, which we placed in the same room. The robot docked itself and began charging. The docking station makes the wall mount for the Roomba Discovery obsolete. iRobot recommends
that you always leave the Roomba plugged in when not in use. This makes sense if you're using the floor-based station, but not for the separate wall mount. Since the wall mount and charger are not attached, you can't keep the Roomba plugged in all the time
if you have it mounted on the wall.