5V 2A Type-C USB 3.7V 18650 Lithium Li-ion Battery Charger Module DIY Power Bank | eBay
Amazon.com: Rechargeable 3.7V Li Lipo Lithium Polymer Ion Battery Pack with 2 Pin 2.0mm/1.25mm JST Connector (502035 300mAh 2.0Jst) : Health & Household
Amazon.com: LCLEBM 3.7V 3800mAh USB Rechargeable Lithium Battery for Button Top with 2 in 1 Charge Cable for Flashlights, Camera, Headlamps, Doorbells, RC Cars (2 Pack) : Electronics