The invention relates to an electrical power source (2) which is intended to be connected to an electric charge by means of a removable connecting cable. The inventive source comprises: a controllable electrical power conversion circuit which is used to convert an electrical input signal into an electrical output signal, at least one characteristic of said electrical output signal being controllable; a control circuit (6) for the controllable power conversation circuit (4) which is used to control said at least one characteristic of the electrical output signal according to a selection code that is representative of the requirements of the connected charge; and a cable presence detection circuit (46) which can deliver a signal indicating the absence of the connecting cable in order to obtain, at the output of the power conversion circuit (4), a common pre-determined quiescent value for said at least one characteristic of the output signal. |