This Li-Ion 18650 battery pack is made from 4 x 2200mAh cylindrical 18650 cells with PCB and a poly switch for maximum protection. Not only is it lightweight, but it has a higher energy density than any rechargeable battery. It has no memory effect, has a longer storage life than NiMH batteries, and can be connected to other PCB ready modules in parallel to build an even larger battery pack.