Article

Journal of Applied Electrochemistry

, Volume 9, Issue 1, pp 125-139

Impedance parameters and the state-of charge. I. Nickel-cadmium battery

  • S. SathyanarayanaAffiliated withDepartment of Inorganic and Physical Chemistry, Indian Institute of Science
  • , S. VenugopalanAffiliated withDepartment of Inorganic and Physical Chemistry, Indian Institute of Science
  • , M. L. GopikanthAffiliated withDepartment of Inorganic and Physical Chemistry, Indian Institute of Science

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Abstract

The problem of nondestructive determination of the state-of-charge of nickel-cadmium batteries has been examined experimentally as well as theoretically from the viewpoint of internal impedance. It is shown that the modulus of the impedance is mainly controlled by diffusion at all states of charge. Even so, a prediction of the state of charge is possible if the equivalent series/parallel capacitance or the alternating current phase shift is measured at a sufficiently low a.c. test frequency (5–30 Hz) which also avoids inductive effects. These results are explained on the basis of a uniform transmission-line analog equivalent circuit for the battery electrodes.