In this paper, a novel fast battery impedance online identification method based on small AC signal injection through controlling of battery-connected inverter is proposed. This method takes several minutes and shows high accuracy while hardly affects normal operation of the system. It is also economical since there is no need to add other components besides the object to be tested (battery) and signal generator (inverter). In view of the widely-used battery-inverter topology in electrified transportation field, this method has potential to popularize in future.