A rotorcraft (G) having an electric circuit and at least one turboshaft engine comprising a gas compressor and a turbine , the turboshaft engine being provided with a starter for driving the gas compressor while starting the turboshaft engine , the electric circuit being connected via a connection bus to an onboard electricity network for delivering direct current to operate the starter under dependency of the electric circuit , the onboard electricity network being maintained at a setpoint voltage during starting by regulating the delivery of electrical energy to the starter by the electric circuit from various sources of electrical energy, including at least one main source of electrical energy for delivering direct current, and at least one secondary source of electrical energy, operation of the secondary source being placed under the dependency of a bidirectional DC-DC converter according to two operating modes of the secondary source, namely: - a so-called discharge operating mode in which the bidirectional DC-DC converter controls the delivery of electrical energy from the secondary source as a function of the value of at least one parameter identifying progress in starting the turboshaft engine , such that additional electrical energy is delivered by the secondary source to the onboard network while starting the turboshaft engine to supplement the electrical energy supplied to the onboard network by the main source , and - a so-called recharging operating mode in which the bidirectional DC-DC converter regulates recharging of the secondary source from the onboard network with electrical current supplied by the main source ; the secondary source of the electric circuit is connected in parallel with the main source ; the secondary source groups together discharge members that are connected in series with the bidirectional DC-DC converter on the electric circuit ; characterised in that the secondary source groups together discharge members that are connected in series on a discharge module of the secondary source and the bidirectional DC-DC converter is a main static converter comprising at least an electrical power architecture and a chopper with N phases shifted by 2n/N; and a regulator device comprises a primary regulation loop and controls the operation of the electrical power architecture of the main static converter , at least by maintaining while starting the turboshaft engine , electrical current intensity equivalence between the electrical current intensity of the electric circuit and the electrical current intensity of the onboard network , regardless of the mode of operation of the discharge module and by monitoring the voltage (Vm) of the discharge module , and the voltage (Vr) of the onboard network . - a so-called discharge operating mode in which the bidirectional DC-DC converter controls the delivery of electrical energy from the secondary source as a function of the value of at least one parameter identifying progress in starting the turboshaft engine , such that additional electrical energy is delivered by the secondary source to the onboard network while starting the turboshaft engine to supplement the electrical energy supplied to the onboard network by the main source , and - a so-called recharging operating mode in which the bidirectional DC-DC converter regulates recharging of the secondary source from the onboard network with electrical current supplied by the main source ; <EOS>