Fenix ARB-L21-5000U Rechargeable Battery

(138 customer reviews)


ARB-L21-5000U is a high capacity 21700 Li-ion USB rechargeable battery built for more power and longer runtimes. This battery has its own USB-C charging port for quick/easy charging without the need for a separate charger. Additional features include a protection circuit in the anode to help prevent short circuits, over charge/discharge and over heating. Pressure relief vents which expel waste gas in the rare case of an internal short circuit preventing an explosion. Battery capacity up to 5000mAh. 500 charging cycles. This product will only work in those models supporting 21700 batteries.  A USB-C charging cord is NOT included. Important Note: THIS BATTERY IS NOT COMPATIBLE WITH 18650 FLASHLIGHTS OR OLDER STYLE CHARGERS. COMPATIBLE CHARGERS ARE THE ARE-A2ARE-A4ARE-D1 OR ARE-D2.

SKU: ARB-L21-5000U
EAN: 6942870369358
For commercial orders and large purchases, contact us at (888) 775-9996 x6, or
WARNING. Be aware of counterfeit Fenix merchandise in the U.S. marketplace.


Specifications of the ARB-L21-5000U Rechargeable Battery

  • 5000mAh high capacity
  • USB Type-C rechargeable battery
  • Protection circuitry to prevent short circuits
  • Pressure vents to prevent explosions
  • 500 charge cycles
  • Indicator light on battery is red while charging, blue when charged
  • Currently compatible with the HT18, LR35R, PD36R, PD40R V2.0, TK22 V2.0, TK22 UE, and TK30.

Capacity: 5000mAh
Voltage: 3.6V
Charging Current: Recommended 1A, maximum 5A
Weight: 2.6 ounces (72.5g)
Size: Length: 2.99″ (76mm) Diameter: 0.85″ (21.5mm)
Warranty Period: 12 month from date of purchase

138 reviews for Fenix ARB-L21-5000U Rechargeable Battery

Based on 138 reviews
  1. Nestor G. (verified owner)

    A solid rechargeable battery with a simple design.

    (0) (0)
  2. Robert (verified owner)

    I don’t need to bring a charger when I travel, only a charging cable, because of the built-in recharge capability. I can also charge in my car, using the USB port.

    (0) (0)
  3. Ted Monson (verified owner)

    Charges easily and quickly.

    (0) (0)
  4. Jonathan (verified owner)


    (0) (0)
  5. Mark L. (verified owner)

    The 5000mh rechargeable battery is great. Nothing more I can say about it.

    (0) (0)
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