Amazon .uk: 18650 Battery 2200mah
High Capacity Rechargeable Battery 2200mAh High Capacity 3.7V Li-ION Battery Icr 1200 Long Life For LED Flashlight,2 Pcs Aspire 2600mAh 18650 20A Battery - 2 Pack, Rechargeable, Flat Top, 3.7 V Li-ion INR, High Performance, Large Capacity, 2ml Cartridge, No Nicotine 3.7 Volt Rechargeable Battery 3500mAh NiMH Battery 2Pack Large Capacity