UltraFire BRC 18650 4000mAh 3.7V Li-ion With PCB Battery (2-pack)
Buy China Wholesale Low Price High Power 18650 4000mah 10a Lithium Ion Batteries For Electrical Electronics Solar Panel & Lithium Ion Battery $1.8 | Globalsources.com
18650 battery pack 4S 14.8V 2500mAh is rechargeable and safe.
Original Cell Battery 3.7V 4000mah with Charger Protection Board Rechargeable | eBay