The battery impedance measuring technique provides accurate estimation of electrochemical parameters. This paper presents an AC current injection circuit, which is connected to the Li-Ion battery in parallel with LC filter-based dc/ac inverter configuration. The proposed approach injects AC perturbation current to the battery in order to measure internal battery impedance without a battery charger. It performs an AC sweep and then, the measured voltage, current, and time data are processed to estimate battery impedance. This data will be utilized for further analysis for preventive maintenance and safety precautions in the battery management system. The performance of the proposed current injection and measurement technique is validated using simulations through PSIM and MATLAB Simulink and was test with 40Ah 13.6V Li-Ion battery.