Fenix Rechargeable Batteries
High-capacity lithium-ion cells built for the demands of high-drain LED flashlights and headlamps. The most common sizes are 18650 and 21700, which power the majority of Fenix handheld lights.
Sizes and capacities
Fenix also offers 16340, 14500, and specialty cells for smaller models. Key specs are capacity in milliamp-hours (mAh) for runtime, discharge rate for high-output performance, and whether the cell includes built-in USB-C charging or requires an external charger. All Fenix batteries include protection circuits to prevent over-discharge and short circuits.
Why manufacturer-matched matters
Using manufacturer-matched batteries ensures your flashlight delivers rated output and runtime. Mismatched or counterfeit cells can damage the light, reduce output, or fail early. If you use your lights daily, keeping one or two spare cells fully charged is the easiest way to guarantee uninterrupted runtime. For charging, see our smart chargers page.
Fenix ARB-L21-6000B
6000mAh Li-ion USB-C Rechargeable Battery
A 21700 6000mAh rechargeable battery with built-in USB-C charging and power-bank output.
Fenix ARB-L21-6000
21700 6000mAh Li-ion Rechargeable Battery
A 21700 6000mAh rechargeable battery with 10A discharge for high-output Fenix lights.
Fenix ARB-L21-5000 V2.0
21700 5000mAh Li-ion Rechargeable Battery
A 21700 5000mAh rechargeable battery (V2.0) with integrated protection circuit.
Fenix ARB-L21-5000U
21700 5000mAh Li-ion USB Rechargeable Battery
A 21700 5000mAh rechargeable battery with built-in USB-C charging.
Fenix ARB-L18-4000
18650 4000mAh Li-ion Rechargeable Battery
An 18650 4000mAh rechargeable battery with 7A discharge and integrated protection.
Fenix ARB-L18-4000U
18650 4000mAh Li-ion USB-CRechargeable Battery
An 18650 4000mAh rechargeable battery with built-in USB-C charging.
Fenix ARB-L18-3500U
18650 3500mAh Li-ion USB Rechargeable Battery
An 18650 3500mAh rechargeable battery with built-in micro-USB charging.
Fenix ARB-L18-1100
Rechargeable 18350 Li-Ion Battery
An 18350 1100mAh rechargeable battery with 7A discharge for compact Fenix lights.
Fenix ARB-L18-1600
Rechargeable 18350 Li-Ion Battery
An 18350 1600mAh rechargeable battery — a drop-in upgrade for Fenix lights that take the ARB-L18-1100.
Fenix ARB-L16-800UP
16340 800mAh Li-ion USB-C Rechargeable Battery
A 16340 800mAh rechargeable battery with built-in USB-C and heavy-load discharge.
Fenix ARB-L14-1600U2
1600mAh Li-ion USB Rechargeable Battery for LD22 V2.0
A 14500-format 1600mAh rechargeable battery with built-in USB charging for Fenix LD22 V2.0.
