*21700 Li-ion batteries are powerful cells designed for commercial applications and must be treated with caution and handled with care. Using low-quality batteries or mishandling batteries (such as short-circuiting or overheating) could lead to combustion and jeopardize the safety of users and property. Any adverse effects resulting from the use of low-quality batteries are not covered by any Fenix warranty or liability. Using quality batteries with circuit protection will reduce the potential for combustion or explosion.

Battery Replacement

Unscrew the tail cap and insert the battery with the anode side (+) towards the light head, then screw the tail cap back on.

Charging

1. Open the anti-dust plug to reveal the USB Type-C charging port, then connect the USB Type-C end of the charging cable to the flashlight.
2. The indicator will display red while charging and will turn green when fully charged.
3. Once charging is completed, be sure to unplug the charging cable and close the anti-dust plug.

Note: 

The flashlight can be operated while charging.
Recharge a flashlight promptly before the battery level drops too low to maintain the optimum battery lifespan.
With the light turned off, the normal charging time of the Fenix ARB-L21-5500 battery is approximately 1.5 hours from depleted to fully charged with a 9 V/2.3 A charging adapter.

Recharge a stored flashlight every four months to maintain the optimum performance of the battery.

Power specifications:

• Charging voltage: 5 V/9 V
• Charging power: 20 W (9 V / 2.3 A)
• This flashlight supports fast charging.
• Only use a certified USB charging adapter that complies with local safety standards.

Battery Level Indication 

With the light turned off, single click the electronic switch to check the battery status, the indicator will last for 3 seconds. Each time the light is turned on, the indicator will show the current battery level and will last for 3 seconds.  

• Green light on: saturated 100% - 85%
• Green light flashes: sufficient 85% - 50%
• Red light on: poor 50% - 25%
• Red light flashes: critical 25% - 1%

*Note: This feature only works with a Fenix ARB-L21 Series battery.

Intelligent Overheat Protection

The flashlight will accumulate a lot of heat when used at high output levels for extended periods. When the flashlight reaches a temperature of 60°C/140°F or above, it will automatically step down a few lumens to reduce the temperature. When the temperature drops below 60°C/140°F, the flashlight will gradually recall the preset output level.

Low-voltage Warning

When the voltage level drops below the preset level, the flashlight is programmed to downshift to a lower brightness level until Eco output is reached. When this happens in Eco output, the battery level indicator blinks red to remind users to recharge or replace the battery in a timely manner.When the voltage level drops below 2.8 V, the flashlight will trigger over -discharge protection and automatically turn off to prevent battery damage,maintain battery lifespan, and ensure safe operation.

*Note: This feature only works with a Fenix ARB-L21 Series battery.

Usage and Maintenance

• Disassembling the sealed head can cause damage to the flashlight and will void the warranty.
• Fenix recommends using an excellent quality battery.
• If the flashlight will not be used for an extended period, remove the battery, or the flashlight could be damaged by electrolyte leakage.
• Lock the flashlight or take out the battery to prevent accidental activation during storage or transportation.
• Long-term use can result in O-ring wear. To maintain a proper water seal, replace the O-ring with an approved spare.
• Periodic cleaning of the battery contacts improves the flashlight's performance as dirty contacts may cause the flashlight to flicker, shine intermittently or even fail to illuminate for the following reasons:

A: Low battery level.
Solution: Replace or recharge the battery.
B: The contact or contact point of the battery or flashlight is dirty.  
Solution: Clean the contact points with a cotton swab soaked in rubbing alcohol.
If the above methods don't work, please contact your authorized distributor.

Warning

• Do NOT directly look at the light source to avoid eye damage.
• All information provided in this user manual is subject to change without prior notice.
• Do NOT place this flashlight in the reach of children!
• Do NOT place the light head near flammable objects, high temperatures can cause objects to overheat and become flammable/ignite!
• Do NOT use this flashlight in inappropriate ways such as holding the unit in your mouth, doing so could cause serious personal injury or death if the flashlight or internal battery fails!
• This flashlight will accumulate a significant amount of heat while operating, resulting in a high temperature of the light shell. Pay close attention to prevent burns!
• This flashlight will accumulate a significant amount of heat rapidly in Turbo mode, resulting in a high temperature of the light shell. Avoid prolonged use to prevent burns!
• Turn off and lock the flashlight to prevent accidental activation when the flashlight is placed in a closed and flammable environment such as pockets and backpacks!
• The LEDs of this flashlight are not replaceable; so the whole flashlight will need to be replaced when any one of the LEDs reaches the end of its lifespan.