The invention concerns a timepiece including a mechanical power source (1) coupled, on the one hand, to first means (5) displaying time related information and, on the other hand, to a generator (2), a regulator circuit (6) for enslaving the generator frequency to a reference frequency, said regulator circuit including switching means (7) arranged for electrically braking the generator when the generator frequency is higher than the reference frequency, and second power-reserve display means (12a) controlled by means for measuring the power-reserve (12b), said timepiece being characterized in that it further includes means (11) for accumulating the electrical energy dissipated during the generator braking periods and means (13) for actuating said second display means to display the power-reserve by means of the electrical energy accumulated.
