NOVELTY - The installation has a battery (2), a super-capacitor (5) and an alternator (1) driven by a heat engine. A supervisor (4) has a comparator to compare the speed of rotation of the alternator with a predetermined threshold speed for regulating an output power of a reversible voltage converter (3) to a reduced power value and a nominal power value if the speed of rotation is less than and greater than the threshold speed, respectively.    USE - Used for supplying high power electrical units e.g. computer and lighting units, embarked with a motor vehicle. Can also be utilized for electrical power steering, X-by wire function and starting assistance.    ADVANTAGE - The supervisor regulates the output power of the reversible voltage converter to reduced power value and nominal power value based on speed of rotation of alternator, thus permitting the supply of the high power electrical units without degrading the quality of on-board electrical network of the vehicle, without drop of transient voltage and without ripple of high voltage, while optimizing the electrical energy contributing to the reduction of fuel consumption of the vehicle. The device assures the simultaneous supply to several high power loads and ensures the electric energy storage in the deceleration phase of the vehicle for reducing the fuel consumption, hence the device can provide the energy during demand of the same equipments without disturbing the on-board electric network of the vehicle. The device has reduced number of units, hence the device has less impact on the electrical architecture of the vehicle. The device can be rapidly installed with several functions such as electrical power steering, X-by wire function and starting assistance with reduced cost.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram illustrating a general structure of an electrical installation.    Alternator (1)    Battery (2)    Reversible voltage converter (3)    Supervisor (4)    Super-capacitor (5)    Consumer (6)