Electrical system of a vehicle with electric propulsion achieved by at least one electrical machine; the electrical system comprises: a storage section provided with at least one battery consisting of a plurality of cells, each of which is connected in series with the other cells and is provided with a bypass branch that is connected in parallel to the cell and has a bypass switch; a section of traction that interacts with the electric machine and is equipped with a power electronic converter that exchanges electrical energy with the storage section; and a section of the auxiliaries which powers auxiliary services of the vehicle requiring an electric supply, comprises a buffer battery, and is electrically powered by the storage section; the electrical system is characterized by the fact that it comprises: a first connecting switch connecting the storage section to the section of traction; a second connecting switch connecting the storage section to the section of the auxiliaries; and a control unit that in order to achieve an exchange of energy between the storage section and the section of traction closes the first connecting switch, opens the second connecting switch, and opens all the bypass switches; and in order to transfer electrical energy from the storage section to the section of the auxiliaries opens the first connecting switch, closes the second connecting switch, and opens a limited number of bypass switches so that the battery presents at its ends a voltage compatible with the nominal voltage of the section of the auxiliaries. a storage section provided with at least one battery consisting of a plurality of cells, each of which is connected in series with the other cells and is provided with a bypass branch that is connected in parallel to the cell and has a bypass switch; a section of traction that interacts with the electric machine and is equipped with a power electronic converter that exchanges electrical energy with the storage section; and a section of the auxiliaries which powers auxiliary services of the vehicle requiring an electric supply, comprises a buffer battery, and is electrically powered by the storage section; the electrical system is characterized by the fact that it comprises: a first connecting switch connecting the storage section to the section of traction; a second connecting switch connecting the storage section to the section of the auxiliaries; and a control unit that in order to achieve an exchange of energy between the storage section and the section of traction closes the first connecting switch, opens the second connecting switch, and opens all the bypass switches; and in order to transfer electrical energy from the storage section to the section of the auxiliaries opens the first connecting switch, closes the second connecting switch, and opens a limited number of bypass switches so that the battery presents at its ends a voltage compatible with the nominal voltage of the section of the auxiliaries. a first connecting switch connecting the storage section to the section of traction; a second connecting switch connecting the storage section to the section of the auxiliaries; and a control unit that in order to achieve an exchange of energy between the storage section and the section of traction closes the first connecting switch, opens the second connecting switch, and opens all the bypass switches; and in order to transfer electrical energy from the storage section to the section of the auxiliaries opens the first connecting switch, closes the second connecting switch, and opens a limited number of bypass switches so that the battery presents at its ends a voltage compatible with the nominal voltage of the section of the auxiliaries.