Battery holder: Li-Ion 18650 Battery Holder (2S1P) With 2.6" long 20AWG & PCB
Amazon.com: Gens ace 3800mAh 7.4V 2S1P TX Lipo Battery Pack with JST-SYP Plug for The QX7 : Toys & Games
SX18650-2S1P Battery for Verifone X970, X990, 2600mAh - sold by smavco - Walmart.com
Amazon.com: Gens ace LiPo Battery Pack 1800mAh 7.4V 45C 2S with Deans Plug for RC FPV Car Boat Truck Heli Foamy Airplane Mini Car Small Helicopter : Toys & Games