NOVELTY - The assembly (21) has a holder (22) comprising a front connecting portion connected with a down tube (16) or head tube (12) of a frame (4) of a human-powered vehicle (1). A rear connecting portion is connected with a seat tube (15) of the frame. The holder is bridged between the down tube or head tube and the seat tube. A battery unit (23) is supported on the holder. The holder includes a bias unit, which urges a movable holder i.e. basket, toward a tilted position in which the movable holder is tilted with respect to height direction of the frame.    USE - Battery assembly for a human-powered vehicle (claimed) e.g. two-wheeled vehicle such as sports bicycle. Can also be used for a mono-cycle, tri-cycle, four wheel vehicle and a wheel chair.    ADVANTAGE - The assembly is demounted or mounted on an appropriate position on the bicycle with less restriction caused by shapes of frames in an easy manner so as to improve desirable weight distribution on the bicycle, easiness of mounting and demounting works and appearance impression of the bicycle by allowing the battery unit to be supported in a tiltable manner along lateral direction from the space defined by the frame. The battery unit is placed directly below a center of mass when a rider is on the bicycle to improve maneuverability such that the assembly is suited for the bicycle requiring high performance. The battery unit is mounted on the frame without using a special frame, which is adapted to shape of the battery unit, while keeping a basic form of the frame so as to reduce faults e.g. strength reduction, of the frame. The battery unit is positioned within a space defined by the frame in a closed position so as to avoid excessive projection from the space defined by the frame.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a human-powered vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a side view of a bicycle.    Human-powered vehicle (1)    Frame (4)    Head tube (12)    Seat tube (15)    Down tube (16)    Battery assembly (21)    Holder (22)    Battery unit (23)