just buy some BL and put them in , its not hard at all , 2 of the same motor , and 2 of the same esc's run one motor on 6 cells and the other on 6 cells , and yoiur good to go , a single BL set up would be fine but only if you wanted a single out drive , why bother havinng 2 when you could have one . less to go rong and eazyer to maintain