Abstract: A battery charger or voltage-reducing power pack is disclosed herein. A molded bobbin, which forms part of the power pack has a mounting head which has elongated slots that receive plug-in prongs with cooperating means between the mounting head and the prongs to prevent endwise movement of the prongs with respect to the slots after insertion therein. The mounting head and base plate have unique interlocking means that cover the exposed edges of the slots to retain the prongs in the slots and also has sturdy interlocking formations to rigidly hold the bobbin with respect to the base plate after assembly.