Abstract: Method and device (1) for controlling an alternator (2) delivering an electrical current which supplies power to electrical consumers (4) in a motor vehicle equipped with an internal combustion engine and which recharges a battery (3), in which method and device, for each journey, the intensity of an excitation current (Ie) for the alternator is controlled as a function of a time profile Ie(t) constructed from a probable time profile (&OHgr;a (t)) of the rotary speeds of the alternator and from the current (Ic) absorbed by the consumers. Preferably, the time profile of the rotary speeds of the alternator is determined from data provided by a navigation device (7) optionally combined with a traffic density information receiver (7′).