@micah78@micah78 If you wire two 18650's into a pack there is enough room for them to fit side/side. It would look something like this with an appropriate connector (XT30 preferable): http://www.vipower.biz/sell-59542-7-4v-2s-2200mah-li-ion-18650-rechargeable-battery-pack.html#.Vb2ElsLbKiM. This box is not designed with integrated battery contacts for 18650 cells however. However, it is also possible that the dual open sled found here (http://www.ebay.com/itm/121656618345) would fit...it's a low profile and narrow sled that I've used in previous designs, but it would need to be fastened with glue. If I were going with dual 18650s in this DNA200 enclosure, I would go the pack route.