A contact-less method to evaluate the state of charge of nickel batteries using Foucault’s eddy currents

A nickel hydroxide electrode and a commercial battery have been studied by a new and contact-less impedance method, based on Foucault’s eddy currents, with the aim of determining their state of charge. Four different current line distributions have been employed and the impedance versus time graphs obtained show a linear variation of this impedance during charge and discharge for all configurations. This new method allows the determination of the state of charge and, furthermore some “artifacts” obvious on these graphs may be useful to detect a deterioration of the studied material.