A method for detecting the state of electrical connection of an energy store, e.g., a battery, to a vehicle's electrical system includes ascertaining operating variables, e.g., battery current I.sub.B and generator current I.sub.G, essentially in time synchronous fashion. When there is a change in the generator current I.sub.G of the generator during a transitional time, the energy store is checked for the value of the battery current I.sub.B for the detection of a compensating effect in the form of a current delivery or a current consumption.