Operating Instructions

Front And Taillight Pairing

By default, press and hold the taillight switch  for about 5 seconds; the taillight indicator  will flash red and green alternately, indicating it has entered the pairing mode; then single click the front light switch, the taillight indicator  will turn steady green, indicating it has received the front light signal; single click the taillight switch again to confirm, and pairing is complete.

*Note:

1. After the initial pairing is completed, the front light automatically remembers the paired taillight, and no further pairing is required.
2. During pairing, the straight-line distance between the front light and the taillight should not exceed 1.5 meters.
3. The pairing wait time for both the front light and the taillight is 60 seconds; if there is no operation within 60 seconds, the pairing mode will automatically exit.
    

Front Light Operation

On/Off

Press and hold the front light switch  for 0.5 seconds to turn on the front light; press and hold its  switch  for 0.5 seconds again to turn off the front light.

Output Selection

With the front light turned on, single click the switch  to cycle through Low→Med→High→Turbo.

Flash Mode

With the front light turned on, double click the switch  to enter the Flash mode; single click the  switch  again to return to the previously used output of the General mode.
*When the front light battery level is below 10%, the flash mode does not work.

taillight Operation

On/Off

Press and hold the taillight switch  for 0.5 seconds to turn the taillight on; press and hold the taillight switch  again for 0.5 seconds to turn off the taillight.

Output Selection

With the taillight turned on, single click the taillight switch  or the front light switch  to cycle through Low→Low Slow-flash→Low Fast-flash→High→High Slow-flash.
The front light switch indicator will simultaneously display the taillight's current output status, steady-on status, or flash frequency.

Standby Mode

With the taillight turned on, press and hold the front light switch  for more than 0.5 seconds, and the taillight will enter the standby mode.
During standby, press the taillight switch  or the front light switch  to wake the taillight and recall the previously used output. If there is no operation within 1 hour after entering standby, the taillight will automatically turn off.
*In standby, the taillight switch  indicator's breathing light flashes green. This indicates the unit is in standby; inserting the charging cable keeps it in standby,  the indicator will give priority to showing the current charging status; if the charging cable is unplugged and it is still in standby, then  the green breathing light will be shown.

Intelligent Memory Circuit

The front and taillights both have intelligent memory circuit excluding Turbo and Flash. When turned on again, the previously used output will be recalled.

Battery Specifications

Warning:

*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.

Charging

1. Open the anti-dust cover, and connect the Type-C end of the charging cable to the charging port of the front or taillight.
2. After the front or taillight receives a charging signal, the battery level indicator displays a steady red light, indicating it is charging.
3. When the battery level indicator's green light is steady, the battery is fully charged.

Note:

1. All outputs of the front or taillight can be used normally while charging.
2. When powered off, the normal charging time of the front light is about 3.5 hours from depleted to fully charged; the normal charging time of the taillight is about 1.5 hours from depleted to fully charged.
3. Once charging is complete, be sure to close the anti-dust cover and press it firmly to prevent dust or foreign objects from entering.
4. Power specifications:

• Charging voltage: 5 V
• Maximum charging power（front light）: 15 W (5 V / 3 A) Maximum charging power（taillight）: 2.5 W (5 V / 0.5 A)
• 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

Each time the product 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 rechargeable battery and is only applicable to the front light.

Battery Replacement

Insert the included battery compartment key into the slot on the front light's tail battery compartment cover, and turn it counterclockwise to open the battery compartment cover. Insert the battery in indicated direction (the battery's anode side should face inward), then tighten the battery compartment cover clockwise.

*Note:

1. Using a sharp tool to pry open the battery compartment may damage the compartment and its surface.
2. The taillight battery is non-replaceable.

Intelligent Overheat Protection

The product will accumulate a lot of heat when used at high output levels for extended periods. When the product reaches a temperature of 50°C/122°F or above, it will automatically step down a few lumens to reduce the temperature. When the temperature drops below 50°C/122°F, the product will gradually recall the preset output level.

Low-voltage Warning

When the battery level is low, the battery level indicator will blink red at 3 Hz to remind users to recharge the battery in a timely manner. To ensure normal use, the product will not turn off automatically, and the battery level indicator will keep blinking till the battery runs out.

Usage and Maintenance

• Disassembling the sealed heads can cause damage to the product and will void the warranty.
• Fenix recommends using an excellent quality battery.
• If the front light will not be used for an extended period, remove the battery, or the front light could be damaged by electrolyte leakage.
• Recharge a stored product every three months to maintain the optimum performance of the batteries.
• Periodic cleaning of the product and battery contacts improves the product's performance as dirty contacts may cause the product to flicker, shine intermittently or even fail to illuminate for the following reasons:
  A: Poor battery level.
  Solution: Recharge or replace the battery.
  B: The contact or contact point of the battery or the product 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 look directly at the light sources, stare at the beams for a long time, or shine this product directly into the eyes of anyone!
• Do NOT place this product in the reach of children!
• Do NOT place light heads near flammable objects, high temperatures can cause objects to overheat and become flammable/ignite!
• Do NOT use this product in inappropriate ways such as holding the product in your mouth, doing so could cause serious personal injury or death if the lights or internal batteries fail!
• This product will accumulate a significant amount of heat while operating, resulting in a high temperature of the light shells. Pay close attention to avoid burns!
• Turn off this product or remove the battery to prevent accidental activation when the product is placed in a closed and flammable environment such as pockets and backpacks!
• The LEDs of this product are not replaceable; so the whole product will need to be replaced when any one of the LEDs reaches the end of its lifespan.

Can the BC28R front light and rear light be linked for synchronized control?

A: Yes.

The BC28R supports intelligent synchronized control between the front light and rear light. After the initial pairing is completed, users can operate the rear light not only with the rear light switch, but also directly switch its output levels using the front light switch for greater convenience.

At the same time, the front light can display the current status of the rear light mode, allowing riders to quickly confirm whether the rear light is in constant-on, slow-flashing, or fast-flashing mode during riding, improving both night riding safety and operational efficiency.

How do I pair the BC28R front light and rear light? What should I note when using them for the first time?

A: Before first use, the front light and rear light must be paired.

Please follow these steps:

• Press and hold the rear light switch for about 5 seconds to enter pairing mode. The rear light indicator will alternately flash red and green.
• Single click the lower switch on the front light. The rear light indicator will turn solid green, indicating that the signal from the front light has been received.
• Single click the rear light switch again to confirm. Pairing is then complete.

Notes:

After the first successful pairing, the front light will automatically remember the paired rear light, so repeated pairing is usually unnecessary.
During pairing, the straight-line distance between the front light and rear light should not exceed 1.5 meters.
If no operation is performed within 60 seconds, the lights will automatically exit pairing mode.

Is the battery in the BC28R front light replaceable? Which batteries are supported?

A: Yes, it is replaceable.

The BC28R front light comes standard with one Fenix ARB-L21-5000 V2.0 rechargeable Li-ion battery. This replaceable battery design allows users to quickly swap batteries during long-distance rides or frequent use, helping reduce range anxiety.

Recommended batteries:

• Fenix ARB-L21-5000 V2.0
• Fenix ARB-L21 Series batteries
• Not recommended or prohibited:
• Fenix ARB-L18 Series batteries
• Standard 21700 rechargeable Li-ion batteries

This is because batteries may differ in size, structure, and protection design. Using an incompatible battery may affect performance and could even create safety risks.

Why does the front light battery level indicator only work with certain batteries?

A: The battery level indication function of the BC28R front light only works with Fenix ARB-L21 Series batteries.

This is because the battery level recognition function is designed based on compatibility with specified batteries. Only matched Fenix ARB-L21 Series batteries can accurately provide the remaining battery level status.
If a non-specified battery is used, the light may still function, but the battery level indication may be inaccurate or may not display properly. For full functionality and more stable performance, we recommend using officially recommended batteries.

Why does the BC28R front light use a cutoff beam design? What are the benefits?

A: The BC28R front light uses a cutoff beam design primarily to illuminate the road ahead while reducing glare for oncoming pedestrians, cyclists, or drivers.

Compared with ordinary flood lighting without a defined cutoff, the cutoff beam directs the light more precisely onto the effective road surface area. This helps riders see the road clearly while also meeting the needs of safe and courteous riding, especially in urban roads and daily commuting environments.

Can the BC28R be used while charging? How long does it take to fully charge?

A: Yes.

Both the front light and rear light can be used normally in all output levels while charging, making them suitable for long rides or temporary power replenishment.

Approximate charging times:

• Front light: about 3.5 hours from fully depleted to fully charged
• Rear light: about 1.5 hours from fully depleted to fully charged

The lights use a USB Type-C charging port. During charging, a solid red indicator means charging is in progress, and a solid green indicator means the battery is fully charged.

What should I do if the light flickers abnormally or cannot be turned on?

A: If the light flickers abnormally or cannot be turned on, please first check the following two common causes:

• Cause 1: Low battery power

  Solution: Recharge the battery promptly or replace the front light battery.

• Cause 2: Dirty conductive contact surfaces

  Solution: Use a cotton swab with alcohol to clean the conductive contact surfaces or contact points on the light or battery.
  If the issue still cannot be resolved after the above checks, please contact your dealer or apply for warranty service according to the after-sales policy.

What is the operating voltage of the BC28R?

A: Charging specifications:

• Charging voltage: 5V
• Front light charging power: supports up to 15W (5V / 3A)
• Rear light charging power: supports up to 2.5W (5V / 0.5A)

What LEDs does the BC28R use?

A: It uses one Cree XHP50D white LED and one red COB light source.

My BC28R needs repair. What should I do?

A:

1. Free replacement and free warranty repair: Within 15 days from the date of purchase, if the product has a quality issue under normal use, the customer may choose either a replacement or repair service. After 15 days, and within 5 years from the date of purchase, if the product has a quality issue under normal use, it is covered by free repair service (the rechargeable battery is covered by a 1-year warranty).
2. Limited lifetime warranty: After the free warranty period has expired (including any extended warranty period), repair charges will be based on the actual cost of replacement materials only, with no additional labor charges.
3. For Warranty service, fill out the warranty form at https://www.fenixlighting.com/pages/warranty-repairs to start your repair claim.