Cell size and capacity
Name meaning~18 mm dia. × 65 mm length
Typical capacityOften ~2,600–3,500 mAh class
Why it mattersHigher capacity usually means longer runtime at similar output
Swap vs built-inRemovable cells let you carry a spare; built-in packs charge in place
Confirm the exact battery listed on the product page before ordering spares.
Charging and backup
USB-C lightsCharge the cell in the light when the port is available
External chargeSome kits charge the 18650 outside the light
CR123A backupMany 18650 hosts also accept CR123A disposables as a field backup
Brightness noteBackup cells may run dimmer than a fresh 18650
Store spare cells protected and follow the product manual for charging and storage.