Lithium polymer batteries have become common in single-cell consumer applications like cell phones and MP3 players, but industrial and commercial applications are now putting them to good use as well. The thin and custom shaped cells are now used in large, complex packs. This white paper is an overview of the advantages, disadvantages and guidelines for using Lithium polymer based battery packs. It looks at Lithium polymer cells versus metal-cased cylindrical and prismatic Li-ion cells and gives a brief description of battery pack construction considerations.