One or more circuits and/or methods are provided. In an example, a circuit includes a first sampling capacitor connected to a first battery terminal for connecting to a battery, an excitation circuit connected to the first battery terminal and configured to generate a first excitation signal, and a measurement circuit connected to the first sampling capacitor and configured to measure charge transferred to the first sampling capacitor by the first excitation signal to generate a charge transfer measurement and to determine a first impedance measurement across the first battery terminal and a second battery terminal for connecting to the battery based on the charge transfer measurement.