A power bank containing a rechargeable battery for wirelessly charging a portable device by induction power transmission, the power bank having a housing having a power transmission surface for placement adjacent a power receiving surface of a chargeable portable device and a reusable adhesive pad over at least part of the power transmission surface, made of an adhesive that is capable of removably sticking to the power receiving surface of a portable device for temporarily holding the surfaces adjacent each other with a protective cover for covering the adhesive pad when not in use and a recess in the housing opposite the power transmission surface for temporarily holding the cover.