We have studied the Dynamic Impedance method as a cell grading and selection guideline for the multi-cell LiB module and battery pack. We have studied a) Cell Open Circuit (OCV), b) cell AC Impedance at 1 K Hz and c) cell initial capacity, which industries have been used for cell grading for the quality control and cell selection guideline for the multi-cell LiB pack. Full range of AC Impedance methode also has been studied for the same purpose.

We found the best condition of the Dynamic Impedance testing for the cell grading and selection guideline through with various variables of a) temperature, b) time, c) type of LiB and d) Capacity of the cell. We applied this technique to the multi-cell LiB modules by serial and parallel cell connections to verify the validation of this method and the impact of this technique.