In this paper, a method is introduced to find out the optimal charge pattern (OCP) of the multistage constant current (MSCC) charge method based on the equivalent circuit model of a Li-ion battery. Unlike the conventional methods, the proposed one does not require several kinds of time-consuming and labor-intensive experiments. The OCP can be simply calculated by the developed equations with the results obtained by a simple experiment. The validity of the proposed method has been verified through the experimental results and it shows that the charge time and the charge energy can be reduced by 12% and 1.8%, respectively, and the charge efficiency of a Li-ion battery can be improved by 0.54% as compared to the conventional constant current-constant voltage (CC-CV) method. A lower temperature rise during the charge can be regarded as an additional advantage of the proposed method.