Electric power supplying device for integration within a mobile telecommunication equipment, comprising an electronic supply circuit having: an input terminal to be plugged to a power grid; an output terminal adapted to be plugged to the mobile equipment; a ground terminal electrically isolated from the input terminal; an electric power source arranged between the input and output terminals, and adapted to supply the mobile equipment with electric power via the output terminal, wherein the electric power source is further connected to the ground terminal; and a rechargeable battery adapted to store electric power, a switching regulator comprising: a servo switch having: a first commutator arranged between the input terminal and the electric power source; and a second commutator arranged between the electric power source and the output terminal; and a management module comprising a first terminal connected to the first commutator and a second terminal connected to the second commutator, the management module being adapted to assess a charge state (A i) of the rechargeable battery, and to drive the servo switch according to said charge state (A i), the first commutator being adapted to direct the electric power coming from the input terminal among the electric power source and the first terminal, the second commutator being adapted to direct the electric power coming from the second terminal among the electric power source and the output terminal, and at least an auxiliary energy (M j) capturing module adapted to collect the auxiliary energy (M j) and a transformation module connected to the capturing module and adapted to transform the auxiliary energy (M j) into electric power, the transformation module being further mounted in parallel on the electric power source between the ground terminal and the second terminal, wherein the second commutator is adapted to direct the electric power coming from the transformation module towards the electric power source and/or towards the output terminal. an input terminal to be plugged to a power grid; an output terminal adapted to be plugged to the mobile equipment; a ground terminal electrically isolated from the input terminal; an electric power source arranged between the input and output terminals, and adapted to supply the mobile equipment with electric power via the output terminal, wherein the electric power source is further connected to the ground terminal; and a rechargeable battery adapted to store electric power, a servo switch having: a first commutator arranged between the input terminal and the electric power source; and a second commutator arranged between the electric power source and the output terminal; and a first commutator arranged between the input terminal and the electric power source; and a second commutator arranged between the electric power source and the output terminal; and a management module comprising a first terminal connected to the first commutator and a second terminal connected to the second commutator, the management module being adapted to assess a charge state (A i) of the rechargeable battery, and to drive the servo switch according to said charge state (A i), the first commutator being adapted to direct the electric power coming from the input terminal among the electric power source and the first terminal, the second commutator being adapted to direct the electric power coming from the second terminal among the electric power source and the output terminal, and at least an auxiliary energy (M j) capturing module adapted to collect the auxiliary energy (M j) and a transformation module connected to the capturing module and adapted to transform the auxiliary energy (M j) into electric power, the transformation module being further mounted in parallel on the electric power source between the ground terminal and the second terminal,