Operating Instructions
On/Off
On:
With the lamp turned off and locked, rotate the rotary switch from “” to any mode to turn on the headlamp.
With the lamp unlocked, press and hold the electronic switch for 0.5 seconds to turn on the headlamp.
Off:
With the lamp turned on, rotate the rotary switch to “” to turn off and lock the headlamp or press and hold the electronic switch for 0.5 seconds to turn off the headlamp.
Mode Switching
Rotate the rotary switch to cycle bidirectionally through Red light mode⇄Lockout mode⇄Spotlight mode⇄Floodlight mode⇄Spot-and floodlight mode.
By default, the rotary switch is set to the Off/Lockout mode.
Output Selection
Spotlight mode: With the lamp turned on, single click the electronic switch to cycle through Low→Med→High→Turbo.
Floodlight mode: With the lamp turned on, single click the electronic switch to cycle through Low→Med→High→Turbo.
Spot-and floodlight mode: With the lamp turned on, single click the electronic switch to cycle through Low→Med→High→Turbo.
Red light mode: With the lamp turned on, single click the electronic switch to cycle through Low→Med→High→Flash.
Turbo mode
In any white light mode, press and hold the electronic switch for 1.2 seconds to enter Turbo mode. In Turbo mode, single click the electronic switch or remain inactive for 60 seconds to recall the previously used mode and output.
*The actual brightness performance in Turbo mode may vary depending on factors such as battery level and working environment. The headlamp features built-in intelligent overheat protection; it is normal for the headlamp to automatically reduce brightness when the temperature exceeds 55°C.
Intelligent Sensing Function
On: With the lamp turned off, press and hold the electronic switch for 6 seconds; the headlamp will blink twice in Low output of Floodlight mode to indicate that this function is enabled.
Off: With the lamp turned off, press and hold the electronic switch for 6 seconds; the headlamp will blink 8 times in Low output of Floodlight mode to indicate that this function is disabled.
Intelligent sensing downshift
When the light head is close to an illuminated object (about 2.36''/60 mm) in white light mode, the headlamp will automatically downshift to Low output. When the light head is away from the illuminated object for over 0.8 seconds, the headlamp will gradually recall the previously used brightness level.
Intelligent Memory Circuit
The headlamp automatically memorizes the last selected output of each mode excluding Red light. When turned on again, the last selected output will be recalled.
*The headlamp will activate in High output if it was previously switched off in Turbo output.
Battery Specifications
Type | Dimensions | Nominal Voltage | Usability |
|
Fenix ARB-L21 Series | 21700 | 3.6 V | Recommended | √√ |
Other Rechargeable Battery (Li-ion) | 21700 | 3.6 V | Caution* | ! |
Battery without Protection Board (Li-ion) | 21700 | 3.6 V | Banned | × |
*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.
Warning:
- Do not use batteries prohibited in this manual, to prevent battery overvoltage from burning out circuit components.
- Do not use batteries without any protection board.
Battery Replacement
Unscrew the battery cover and insert the battery in accordance with the polarity marks, then screw the battery cover back on.
Charging
- Open the anti-dust cover and plug the USB Type-C end of the charging cable into the charging port of the headlamp.
- When charging, the indicators will light up in sequence to display the charging status. The four indicators will be constant-on after charging is completed.
- Once charging is completed, be sure to unplug the charging cable and close the anti-dust cover to prevent the ingress of dust and debris.
- With the lamp turned off, the charging time of the included Fenix ARB-L21-5000 V2.0 battery is approximately 1.5 hours from depleted to fully charged with a 5 V/2.5 A or above charging adapter.
Note:
- The headlamp can be operated while charging, with all outputs available except for Turbo.
- Recharge a stored headlamp every four months to maintain the optimum performance of the battery.
- Only use a certified USB charging adapter that complies with local safety standards.
Battery Level Indication
With the lamp turned off, single click the electronic switch to check the battery status. Single click once again the indicator(s) will go out immediately, or without any operation the indicator(s) will last for 3 seconds. Each time the lamp is turned on, the indicator(s) will show the battery level and will last for 3 seconds.
- Four lights on: 100% - 80%
- Three lights on: 80% - 60%
- Two lights on: 60% - 40%
- One light on: 40% - 20%
- One light flashes: 20% - 1%
*This only works with a Fenix ARB-L21 Series battery.
Intelligent Overheat Protection
The headlamp will accumulate a lot of heat when used at high output levels for extended periods. When the headlamp reaches a temperature of 55°C/131°F or above, it will automatically decrease the brightness to reduce the temperature. When the temperature drops below 55°C/131°F, the headlamp will gradually recall the preset output level.
Low-voltage Warning
When the voltage level drops below the preset level, the headlamp is programmed to downshift to a lower brightness level until the Low output is reached. When this happens in Low output, one of the battery level indicators blinks to remind users to recharge or replace the battery in a timely manner.
Headband Assembly
Notice: The headband is factory assembled and ready to use right out of the package.
Adjust the headband by sliding the buckle to the required length.
Usage and Maintenance
- Disassembling the sealed head can cause damage to the headlamp and will void the warranty.
- Fenix recommends using an excellent quality battery.
- If the headlamp will not be used for an extended period, remove the battery, or the lamp could be damaged by electrolyte leakage.
- Remove 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 lamp's performance as dirty contacts may cause the lamp to flicker, shine intermittently or even fail to illuminate for the following reasons:
A: Low battery level.
Solution: Recharge or replace the battery.
B: The contact or contact point of the battery or headlamp is dirty.
Solution: Clean the contact points with a cotton swab soaked in rubbing alcohol.
If the above methods don't work, please contact the distributor.
Warning
- Do NOT place this headlamp in the reach of children!
- Do NOT shine this headlamp directly into the eyes of anyone!
- Do NOT place light head near flammable objects, high temperatures can cause objects to overheat and become flammable/ignite!
- Do NOT use the headlamp in inappropriate ways such as holding the unit in your mouth, doing so could cause serious personal injury or death if the headlamp or internal battery fails!
- This headlamp will accumulate a significant amount of heat while operating, resulting in a high temperature of the lamp shell. Pay close attention to avoid burns!
- Turn off the headlamp or remove the battery to prevent accidental activation when the headlamp is placed in a closed and flammable environment such as pockets and backpacks!
- The LEDs of this headlamp are not replaceable; so the whole lamp will need to be replaced if any one of the LEDs reaches the end of its lifespan.


