APPARATUS FOR RECHARGING A BATTERY

摘要

Apparatus (1) for recharging a battery (5), comprising a compartment (3) into which the battery (5) can be placed so that its electrical terminals are in contact with a pair of electrodes (7, 9), said electrodes (7, 9) being connectable to corresponding poles of a controllable source (11) of electrical energy, whereby the compartment (3) comprises a ferromagnetic body (15) which is positioned so as to be subjected to mechanical stress in response to mechanical deformation of the battery (5), and the apparatus (1) comprises electrical means (23) for monitoring the magnetic permeability mu of the ferromagnetic body (15). Such monitoring can be achieved, for example, by measuring the self-inductance of a coil (21) surrounding at least a portion of the ferromagnetic body (15). The invention exploits the insight that mu is caused to change by magnetostrictive effects arising from mechanical stress of the ferromagnetic body (15) in response to mechanical deformation of the battery (5) during charging. Expansion of the battery (5) can be used as an indicator that charging has been completed, and that the battery (5) should be disconnected from the source of electrical energy (11).