NOVELTY - The system has a battery protection unit (11), and two control units (10) connected to terminals of electrochemical generators and measuring an operation parameter e.g. generator temperature, of the generators and controlling the protection unit by transmitting carrier currents on a power line. The protection unit includes an interrupter inserted in the power line for interrupting charge and discharge of a rechargeable battery. Each control unit includes a current sensor detecting current in the power line and an interrupter controlled by the sensor.    USE - Used for controlling charge and discharge state of a rechargeable battery that includes lithium/ion generators, sliver/zinc generator, polymer generator, nickel/cadmium accumulator, nickel/metal hydride accumulator or lead generator (claimed), and is utilized for supplying electrical energy to an electric vehicle.    ADVANTAGE - The control units measure the operation parameter of the electrochemical generators and directly control the protection unit by transmitting carrier currents on the power line, thus avoiding the use of the master controller to control the battery protection units and reducing connecting wires by avoiding wires intended to transmit the measurements of the operation parameters between generator interfaces and the master controller. The system therefore reduces the fabrication cost of the batteries. The system also ensures that the control signals are transmitted through an existing power line and not through dedicated wired connections, thus further simplifying the wiring of the system. The system uses boards that constitute the control units, are associated to the generators and not specific to certain type of batteries, thus avoiding fabrication of boards for each battery type, simply duplicating the same board irrespective of the number of generators and reducing the cost of the system by undifferentiated mass production of the control units. The control units can detect charge end of one generator and control the current bypass in order to ensure equilibrium with other generators. The system also optimizes the power consumption of the control units and conserves the battery capacity.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method of controlling the voltage of a battery.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic of a battery controlling system.    Electrochemical generators (2)    Power line (3)    Control units (10)    Battery protection unit (11)    Interrupter (12)    Electrical connections (13, 14)