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Fenix 21700 Rechargeable Li-ion Battery – 5000 mAh


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SKU: FX-ARB-L21-5000 Categories: , , ,

The Fenix ARB-L21-5000 is a 21700 (21mm X 70mm) rechargeable Li-ion battery.  For comparison, a typical 18650 battery is 18mm X 65mm. This new size lithium ion is a replacement for flashlights that can accept the larger battery such as the Fenix PD36R.  With its 3.6 volts of power and 5000mAh capacity make it the perfect companion for high-drain flashlights, providing sufficient power and extra-long runtimes. Fitted with multiple protection systems, the button-top Fenix ARB-L21-5000 has 3 sets of overheat protection to ensure that the battery remains at a sustainable temperature. There are protection circuits embedded into the anode for overcharge, over-discharge, and short circuit protection as well. The steel shell riveting encasing the battery decreases any potential risk of the cell short-circuiting due to impacts, drops, or collisions combined with the pressure relief vents which will expel generated gas from a potential short-circuit to eliminate hazardous conditions within the battery


  • Fenix ARB-L21-5000mAh Rechargeable 21700 Battery
  • Lithium-ion; Button-Top Design
  • 3.6V 5000mAh
  • Max Charging Current: 1.0A recommended; 5A maximum
  • 7.5A maximum current
  • Protection circuit built-in the anode with a steel hat by riveting process. Steel shell eliminates the risk of short circuit caused by collision and impact.
  • Pressure Relief Vent: Expels waste gas generated by internal short circuit. Expelling waste gas prevents a cell from inflating or exploding.
  • Three Sets of Over-Heat Protection:  Over charge protection, Over discharge protection, Short circuit protection, and overheating protection
  • 500 Charge Cycles: Properly maintained, battery is designed to retain up to 75% of its original capacity at 500 full charge and discharge cycles
  • Weight: 2.56 Ounces
  • Height: 2.99"
  • Diameter: 0.85"
  • Note: Many older external chargers are sized to fit batteries to a maximum of 65mm in length.  21700 batteries are 70mm in length.  Be sure to double-check your existing flashlight and external charger specifications.


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