NOVELTY - The system has a sensing unit (4) to sense a value of an electrical voltage of a storage battery (2). A signal transmission unit (5) transmits a signal proportional to the sensed value of the electrical voltage, to a remote receiver apparatus (6) of a user. A signal reception unit (7) belonging to the receiver apparatus receives the signal. A processing unit (8) processes sensed voltage value.    USE - Used in a specialized workshop for measuring operating state such as charging state, of an energy supply unit e.g. storage battery and alternator or current generator, placed below a seat in a vehicle e.g. car (claimed), where the supply unit supplies power for starting the vehicle.    ADVANTAGE - The system permits any user to previously and rapidly know the possible operation anomalies of the energy supply unit in real time before detected by a mechanic or by an automobile electrician. The system allows the user to notify operation inefficiency state of the energy supply unit for allowing him to intervene in an appropriate manner before starting the vehicle, thus limiting annoyance of the owner such as difficult starting of the vehicle caused by the failure of the supply unit. The system allows to prolong the life duration of the functionalities of the energy supply unit. The system eliminates the necessity of accessing inconvenient positions such as the seats of the vehicle, or eliminates opening of the trunk to verify the operating state. The system can be easily designed at low cost.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method to measure operating state such as charging state of an energy supply unit of a vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of an energy supply unit operating state measuring system.    Storage battery (2)    Electrical voltage value sensing unit (4)    Signal transmission unit (5)    Remote receiver apparatus (6)    Signal reception unit (7)    Signal processing unit (8)