The invention relates to alternators for a motor vehicle, of which a stator comprises a cylindrical body, several phases each formed by a plurality of electrically conducting elements, the cylindrical body comprising radial slots for accommodating at least four phase-conductor elements forming at least four layers of conductor elements, each conductor element including two branches placed in slots each in a predetermined layer and a head forming a U-shape seen in the peripheral direction, the half of the conductor elements which are engaged by their first branches in a slot being engaged by their second respective branches in the same other slot. According to the invention, at least first and second conductor elements of such half are such that the radii of curvature of the U-shapes of the two conductor elements are substantially identical.