putting lipoly packs in parallel means using the same total cells per set. ALSO, the discharge capability I.E., 15C, 20C, 25C, 30c, 40c, 40-50c has to be the same,,, not just the same cells in series. Two packs of equal voltage with different rate of discharge, will heat up, and maybe smoke or burn. The discharge rate has to be matched for all cells in packs.