Board Thread:General Nerf discussion/@comment-27035444-20160821193230/@comment-27103116-20160822182544

These are normal Lithium-Ion rechargeable C batteries, and they do sell in 2-packs separate from the charger for around $8 USD. So they work in the stock ports.

http://www.onlybatteries.com/showitem.asp?ItemID=16272.21&cat1=28&uid=1381&vfpr=30.50&vfbr=Multiplier&vfcat=Electronics+Electronics+Accessories+Power+Batteries&vfsku=16272&vfbi=no_bid&sid=gpla&vfsku=16272&vfsku=16272&gpla=pla&gclid=CjwKEAjwxeq9BRDDh4_MheOnvAESJABZ4VTqoqtI5nkxaTdx5NR0biMSl0MAkGyKZe31McWQipeXLxoCvJnw_wcB