Fenix ARB-L18-4000 18650 4000mAh Rechargeable Li-ion Battery

Battery Compatibility: 

• 18650 battery sizes vary by brand and model. Even a few millimeters can make a battery incompatible with your flashlight. • Please verify the correct length and type (Flat Top or Button Top) before purchasing. Thank you for your understanding.

The Fenix ARB-L18-4000 is a high-capacity rechargeable 18650 lithium-ion battery designed for compatible Fenix flashlights and other devices using protected 18650 batteries.

With a 4000mAh capacity and a stable 7A maximum output current, it provides extended runtime while maintaining reliable performance in high-output lighting applications.

The battery features built-in protection circuitry to help protect against short circuits, overcharging, over-discharging and overheating. Integrated pressure vents provide an additional layer of safety.

Unlike the longer ARB-L18-4000U version, this battery does not include a built-in USB-C charging port, making its shorter 69.2 mm length important for compatibility with devices that cannot accommodate extended-length 18650 batteries.

FEATURES

• Genuine Fenix rechargeable battery
• 18650 Li-ion battery
• 4000mAh high capacity
• 3.6V nominal voltage
• Maximum output current: 7A
• Integrated protection circuitry
• Helps protect against short circuits
• Overcharge and over-discharge protection
• Overheating protection
• Pressure relief vents for added safety
• Up to 500 charge cycles
• Designed to retain approximately 75% capacity after 500 cycles

SPECIFICATIONS

Brand: Fenix
Model: ARB-L18-4000
Battery Type: Rechargeable Li-ion
Battery Size: 18650
Capacity: 4000mAh
Energy: 14.4Wh
Voltage: 3.6V
Recommended Charging Current: 2A
Maximum Charging Current: 4A
Maximum Output Current: 7A
Length: 69.2 mm / 2.72 in
Diameter: 18.75 mm / 0.74 in
Weight: 55 g / 1.94 oz
Maximum Charge Cycles: Up to 500
Built-in USB Charging: No
Protection Circuit: Yes

DIMENSIONS & COMPATIBILITY

Battery Dimensions:
69.2 mm long × 18.75 mm diameter

The ARB-L18-4000 is a protected 18650 battery and is slightly longer than an unprotected standard 18650 cell.

Always verify the available battery compartment dimensions before purchasing, especially when using the battery in non-Fenix products.

Important: Do not confuse this model with the Fenix ARB-L18-4000U USB-C battery, which is approximately 72 mm long and may not fit devices designed for the shorter ARB-L18-4000.