The invention relates to a method and device for managing the charging and discharging of ultracapacitors without control wiring, connected in parallel to the electrical system of a combustion engine, or any other device or process that needs a battery to supply or absorb strong electrical currents. The device is advantageous in that, for the operation thereof, it is not necessary to modify the electrical wiring of the engine and it allows the operation of the engine even when the battery is partially charged, completely discharged, or when there is no battery. The invention relates to a portable embodiment, an embodiment for permanent use and another embodiment in which the device is connected to an electrochemical battery forming an assembly, which is used to supply the engine with electrical energy.