Apparatus and method for determining the type of a battery or accumulator by use of magnetic fields

In an apparatus for determining the contents of a battery or accumulator (10), the inductive coupling provided by the battery or accumulator (10) between an excitation coil (20) and a sense coil (30) is measured. To improve the selectivity of the apparatus magnets (41, 42) are provided that generate a quasi-static magnetic field during a measurement. The quasi-static magnetic field saturates the iron in an ornamental jacket of the battery or accumulator (10) so that the inductive coupling between excitation coil (20) and sense coil (30) is almost completely determined by the interior of the battery or accumulator (10). The inductive coupling at different frequencies, with and without the quasi-static magnetic field, yields a reliable identification. The excitation coil (20) can be energised by a current source (21, 22, 23) generating an alternating current with constant amplitude. Thereby, the signal in the sense coil (30) is insensitive to the change in self-induction of the excitation coil (20) due to the presence or absence of a battery (10).