Description
Experience the next generation of 21700 power with the genuine Fenix ARB-L21-5000 V2.0, an upgraded protected button top battery that delivers a massive 5000mAh capacity with enhanced 10A continuous discharge. Designed for high-output LED flashlights, headlamps, and outdoor lighting, this V2.0 edition provides improved current delivery, longer cycle life, and rock-solid reliability. The integrated protection circuit safeguards against overcharge, over-discharge, and short circuits, while the raised button top ensures perfect contact in Fenix and most other 21700 flashlight brands. With approximately 43% more energy than a standard 3500mAh 18650, the ARB-L21-5000 V2.0 is the ultimate runtime upgrade for serious illumination needs.
Key Features
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5000mAh Maximum Capacity – Among the highest capacity available in the 21700 form factor. Delivers exceptionally long runtime for high-output devices, significantly extending usage time between charges.
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V2.0 Upgraded 10A Continuous Discharge – Enhanced from the original version, the V2.0 provides a full 10A continuous output, offering better performance for today's high-power LED flashlights and devices.
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Built-in Protection Circuit – Safeguards against overcharge (4.2V cutoff), over-discharge (2.5V cutoff), short circuits, and overcurrent, protecting both the battery and your valuable equipment.
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Button Top Design – Raised positive terminal ensures reliable electrical contact in Fenix and most other 21700 flashlights and devices requiring a button top.
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Long Cycle Life – Retains over 80% of initial capacity after 500 charge/discharge cycles under recommended conditions, reducing long-term replacement costs.
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Fenix Genuine Quality – Manufactured to strict standards with premium 21700 cell core and advanced protection circuitry for consistent, safe performance in demanding applications.
Parameters
Applications
Recommended For
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High-Output 21700 LED Flashlights: Perfect for Fenix and other 21700-powered flashlights. The 5000mAh capacity provides exceptionally long illumination time—approximately 43% more energy than a standard 3500mAh 18650 cell. Ideal for search and rescue, professional inspection, and extended outdoor use.
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Headlamps (21700 Compatible): Extended runtime for professional, industrial, and outdoor applications. The protection circuit prevents over-discharge damage when lights are accidentally left on.
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Camping Lanterns & Emergency Lights: Reliable power for extended trips and power outages. The 5000mAh capacity ensures lights stay on through the longest nights.
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Bicycle Lights: Consistent output for night riding, endurance events, and multi-day touring without battery changes.
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Smart Doorbells & Security Cameras (21700 Compatible): Ultra-long standby with reliable power for motion detection and recording events.
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Portable Fans & Outdoor Gadgets: Suitable for any 21700-powered device drawing under 10A where maximum runtime is desired.
Not Recommended For
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High-Power Vaping / Mechanical Mods: These require 15–35A unprotected cells. The 10A protection limit is insufficient for sub-ohm applications.
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Cordless Power Tools: Drills, saws, and impact drivers demand 20–40A continuous current, far beyond this battery's 10A protection limit.
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RC Cars, Drones & High-Drain Models: These require 20–30A+ continuous current. This battery will not function and may trigger protection.
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18650-Only Devices: This is a 21700 cell (21mm diameter) and will not physically fit in 18650 battery compartments.
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Multi-Cell Series Packs: Individual protection boards may conflict. Use matched unprotected cells with an external BMS instead.
FAQ
Q: What's new in the V2.0 version compared to the original ARB-L21-5000?
A: The V2.0 version features an upgraded protection circuit that supports up to 10A continuous discharge (vs. approximately 8A on the original), improved cycle life performance, and refined internal construction for more consistent power delivery. It remains fully backward compatible with all devices that accept the original ARB-L21-5000.
Q: Is this battery compatible with my Fenix 21700 flashlight?
A: Yes. The ARB-L21-5000 V2.0 is specifically designed for Fenix 21700 flashlights and is compatible with most other brands requiring a button top 21700 cell. Due to the protection circuit and button top, the battery is approximately 71mm long. Most 21700 flashlights are designed to accommodate protected cells, but please verify your device's battery compartment specifications before ordering.
Q: Can I use this battery in my 18650 device?
A: No. The 21700 format has a larger diameter (21mm vs. 18mm for 18650) and will not physically fit into 18650 battery compartments. Only use this battery in devices specifically designed for 21700 cells.
Q: What does "protected" mean and why should I choose a protected cell?
A: A protected cell has a small circuit board that automatically prevents overcharge (above 4.2V), over-discharge (below 2.5V), short circuits, and excessive current draw (above 10A for this V2.0). This makes single-cell use much safer, especially in devices without their own battery management. The trade-off is a slightly longer cell (71mm vs. ~70mm) and a current limit of 10A.
Q: Can I use this battery for vaping or power tools?
A: No. Vaping devices and power tools require high continuous currents (typically 15–40A). The ARB-L21-5000 V2.0's protection circuit limits output to approximately 10A. Using it in such devices will cause the protection to cut off power or may damage the battery. Please use dedicated unprotected high-drain cells for those applications.
Q: How should I charge and store this battery?
A: Use a quality lithium-ion battery charger with a CC-CV algorithm designed for 21700 cells. Fenix chargers are an excellent match. Charge at 0.5C (2.5A) for best longevity. Store at approximately 3.6–3.7V (40–50% charge) in a cool, dry place using a non-conductive battery case. Avoid storing fully charged or fully discharged for extended periods.
