VEHICLE ELECTRICAL SYSTEM

An onboard power supply system for supplying at least one consumer with electrical energy in a vehicle comprises: - a first voltage detection arrangement (55) for detecting the voltage level in a line region (51) between an input terminal (34) of a first disconnect switch (26) and a first battery (16), - a second voltage detection arrangement (57) for detecting the voltage level in a line region (53) between an input terminal (42) of a third disconnect switch (30) and a second battery (18), - a third voltage detection arrangement (58) for detecting the voltage level in the region of a consumer connection line region (12), - an overvoltage detection arrangement (62) for detecting an overvoltage in the region of the consumer connection line region (12) on the basis of the voltage level detected by the third voltage detection arrangement (58) and for switching the first disconnect switch (26) and the third disconnect switch (30) to their open state upon detection of an overvoltage in the region of the consumer connection line region (12).