A theoretical equivalent circuit model of two 40 Ah commercial batteries supplied by Saft was formulated to interpret electrochemical impedance spectra as a function of temperature at zero state-of-charge. The batteries were chosen to represent viable and non-viable products from the Saft production line. This paper is the first contribution from a project in Newcastle to develop a rapid, non-destructive analytical method for quality control on the battery production line. Using the model, it proved straightforward to discriminate between viable and non-viable batteries based on the temperature dependence of the electrochemical reaction kinetics at the electrodes, the average diffusion coefficients and the charge transfer resistances. Furthermore, as well as marked differences, for example, between the time constants, activation energies, polarisation resistances of the viable and non-viable batteries, the individual contributions of the anodes and cathodes in the batteries were de-convoluted and interpreted through the model framework.