Amazon.com: ElecGear Lithium ion Battery Pack for Xbox Wireless Controller, 2X 1200mAh Li-ion Rechargeable Battery for Xbox Series X/S, Xbox One Video Game Controller with 2X Play and Charge USB Cable :
12V 3S 7P 40A BMS Li-ion Battery Pack DIY Kits Case Holder for 18650 Power Wall/ | eBay
Lithium Ion Battery Pack - 3.7V 4400mAh : ID 354 : $19.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Lithium Ion Battery Pack, 3.7 V, for Solar Appliances