Devices and/or methods for determing the availability of electric energy, in particularly in vehicle electric systems comprising several energy accumulators

Devices and/or methods for determining the availability of electrical energy in dual energy-storing means and on-board electrical systems, in which the two energy-storing means, in particular batteries, can communicate with one another via a direct-voltage converter. The requisite electrical energy is generated by means of a generator driven by the vehicle engine. The usual consumers are connected to a first consumer battery circuit 10, 24 . Further consumers, such as high-current consumers and in particular the starter, communicate with the second battery circuit 11, 29 . A control unit, for instance a control unit with a microprocessor, ascertains the availability of the electrical energy and any defects that occur by evaluating various algorithms and performs the requisite triggering and signalling operations. The algorithms include threshold value statements on the availability of the electrical energy (SOCS) and threshold value statements for detecting system defects (SOHS).