The battery compartment on the Combi Bike Plus is located in the bottom of the exerciser. Tilt the exerciser and the battery can be removed. It is hidden behind a battery compartment that is kept in place with a magnet. Just lift up the battery holder. Note that on some of the bikes tools must be used, others the hatch is held firmly with a magnet. On the BedBike the battery compartment is below the handle. Attached with a magnet, it easily flips up when the handle is fully closed (least opening of the handle)