Amazon.com: Amityke 3.7 Volt Rechargeable Battery 3500mAh Battery 2Pack Large Capacity Batteries for Headlamp, LED Flashlight, etc : Health & Household
3.7V 7800mAh Rechargeable Lithium Battery Red
Lithium Ion Polymer Battery - 3.7V 70mAh | TinyCircuits.com
Lithium Ion Polymer Battery with Short Cable - 3.7V 350mAh : ID 4237 : $5.95 : Adafruit Industries, Unique & fun DIY electronics and kits