Operating Instructions
On/off
Press and hold the side switch for 0.5 seconds to turn on/off the flashlight.
Mode switching
Press and hold the side switch for 1.2 seconds to switch to the Flash mode. Single click the side switch to select between Strobe and SOS.
Output selection
In General mode, single click the side switch to cycle through Eco→Low→Med→High→Turbo.
Lock/unlock
- Lock: With the light turned off, double click the side switch within 0.5 seconds, the light will blink twice in Low output to indicate the locked status.
- Unlock: With the light locked, double click the side switch within 0.5 seconds, the light will activate in Low output to indicate that the light is unlocked.
Note: In locked status, any operation other than battery level indication and unlocking will activate two blinks in low output to indicate the locked status.
Intelligent Memory Circuit
The flashlight automatically memorizes the last selected output of General mode. When turned on again in General mode, the last selected output will be recalled. When turned on again in Flash mode, the flashlight will always activate in Strobe.
Battery Specifications
Type | Dimensions | Nominal Voltage | Usability | |
Fenix ARB-L21 Series | 21700 | 3.6 V | Recommended | √√ |
Rechargeable Battery (Li-ion) | 21700 | 3.6 V | Caution* | ! |
Rechargeable Battery (Li-ion) | 16340 | 3.6 V | Banned | × |
Rechargeable Battery (LiFePO4) | 18650 | 3.2 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.
Battery Replacement
Unscrew the light tail and insert the battery with the anode side (+) towards the light head, then screw the light tail back on.
Charging
- 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.
- The indicator will display red while charging and will turn green when fully charged.
- 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-L21-5000 V2.0 battery is approximately 1.5 hours from depleted to full charged with a 9 V/3A 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 the government safety standards of the country or region where this product is sold.
Battery Level Indication
With the light turned off, single click the side switch to check the battery status, the indicator in the side switch 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 only works with a Fenix ARB-L21 Series rechargeable 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 3.0 V, 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 rapidly, and the main light blinks for 20 seconds to remind users to replace or recharge the battery in a timely manner. Single click the side switch to stop the main light from blinking and return to Eco output. After the 20-second blinking ends, the flashlight can be used in Eco output for over 30 minutes. Throughout this warning period, the battery level indicator continues to blink red rapidly until the battery runs out.
Note: This only works with a Fenix ARB-L21 Series rechargeable 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.
- Unscrew the light tail a few turns 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: Poor battery level.
Solution: Replace or recharge the battery (Ensure the battery is inserted according to the manufacturer’s specifications).
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 place this flashlight in the reach of children!
- Do NOT shine this flashlight directly into anyone’s eyes!
- 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 avoid burns!
- Take out the battery 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 light will need to be replaced if any one of the LEDs reaches the end of its lifespan.


