Abstract: The invention relates to devices and/or methods for determining the availability of electrical energy in two-energy accumulator vehicle electric systems, in which both energy accumulators, particularly batteries, can be connected to one another via a D.C. converter. The required electric energy is generated by means of a generator that is driven by a vehicle engine. The customary consumers are connected to a first consumer battery circuit (10, 24). Additional consumer, for example, high-current consumers, particularly the starter, are connected to the second battery circuit (11, 29). A control device, for example, a controller that is equipped with a microprocessor determines the availability of the electric energy and occurring faults while evaluating.

Abstract: 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).