Battery cell impedance measurement method and apparatus

A circuit arrangement for determining impedance of a battery cell is provided. A first circuit is configured to generate sine and cosine waveforms having N sample values per period. A second circuit is coupled to an output of the first circuit and is configured to input a current into the cell in response to the sample values of the cosine waveform. The current has an amplitude proportional to the sample values of the cosine waveform. A third circuit is coupled to the cell and configured to sample voltage levels across the cell resulting from the current being input into the cell. A fourth circuit is coupled to an output of the third circuit and is configured to separate each voltage level sampled by the third circuit into real and imaginary components.