{"product_id":"fenix-21700-rechargeable-battery-3-6volt-li-ion-batteries-4900mah-large-capacity-button-top-for-led-flashlight-headlamp","title":"Fenix ARB-L21-4900 21700 4900mAh 10A 3.6V Button Top Protected Battery – for Flashlights, Headlamps \u0026 Outdoor Lights","description":"\u003ch4\u003e\u003cspan class=\"\"\u003eDescription\u003c\/span\u003e\u003c\/h4\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan class=\"\"\u003eGet flagship-level endurance without the flagship price with the genuine Fenix ARB-L21-4900, a protected 21700 button top battery that delivers an impressive 4900mAh capacity. Designed for high-output LED flashlights, headlamps, and outdoor lighting, it provides near-identical runtime to 5000mAh cells at a more accessible value. The integrated overcharge, over-discharge, and short-circuit protection ensures safe, worry-free operation, while the raised button top guarantees reliable contact in Fenix and most other 21700 flashlight brands. With excellent cycle life and Fenix's trusted quality, the ARB-L21-4900 is the smart choice for users who want maximum practical runtime without overpaying.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch4\u003e\u003cspan class=\"\"\u003eKey Features\u003c\/span\u003e\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003e4900mAh Near-Flagship Capacity\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Delivers virtually the same runtime as 5000mAh cells—only about 2% less. Provides approximately 40% more energy than a standard 3500mAh 18650. Ideal for users who want top-tier endurance at a better value.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003e10A Continuous Discharge\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Supplies stable, reliable power for demanding LED flashlights and outdoor equipment. Enough current for turbo modes and high-output settings without triggering protection.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eBuilt-in Protection Circuit\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Safeguards against overcharge (4.2V cutoff), over-discharge (2.5V cutoff), short circuits, and overcurrent (10A limit), protecting both the battery and your valuable devices.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eButton Top Design\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Raised positive terminal ensures reliable electrical contact in Fenix and most other 21700 flashlights and devices requiring a button top.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eLong Cycle Life\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Retains over 80% of initial capacity after 500 charge\/discharge cycles under recommended conditions, reducing long-term replacement costs.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eFenix Genuine Quality\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Manufactured to strict standards with a premium 21700 cell core and advanced protection circuitry for consistent, safe performance.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003e\u003cspan class=\"\"\u003eParameters\u003c\/span\u003e\u003c\/h4\u003e\n\u003cdiv class=\"ds-scroll-area ds-scroll-area--show-on-focus-within ds-scroll-area--enabled _1210dd7 c03cafe9\"\u003e\n\u003cdiv class=\"ds-scroll-area__gutters\"\u003e\n\u003cdiv class=\"ds-scroll-area__horizontal-gutter\"\u003e\u003c\/div\u003e\n\u003cdiv class=\"ds-scroll-area__vertical-gutter\"\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cspan class=\"\"\u003eParameter\u003c\/span\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cspan class=\"\"\u003eSpecification\u003c\/span\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003cbr\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eModel\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eFenix ARB-L21-4900\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eBattery Type\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e21700 Button Top Protected Lithium-Ion\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eTypical Capacity\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e4900 mAh (0.2C discharge to 2.5V)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eMinimum Capacity\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e~4800 mAh\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eNominal Voltage\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e3.6 V (typical operating 3.7 V)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eMax Continuous Discharge\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\n\u003cstrong\u003e\u003cspan class=\"\"\u003e10 A\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e (limited by built-in protection circuit)\u003c\/span\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eProtection Functions\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eOvercharge (4.2V cutoff), Over-discharge (2.5V cutoff), Short Circuit, Overcurrent\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eDischarge Cut-off Voltage\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e2.5 V (automatic protection cutoff)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eStandard Charge\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eCC-CV, 0.5C (2450 mA) to 4.2 V, cut-off 50 mA (use a quality Li-ion charger)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eInternal Resistance\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eApprox. 40–60 mΩ (including protection circuit and button top)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eCycle Life\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e≥ 500 cycles (to 80% capacity)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eOperating Temperature (Discharge)\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e-20°C to 60°C\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eTop Type\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eButton Top\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eDimensions\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eApprox. 21.5 mm diameter × 71.0 mm length (~1mm longer than standard unprotected 21700)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eWeight (single cell)\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eApprox. 70 g\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003ePackage Includes\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e1 × Fenix ARB-L21-4900 protected button top battery\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003cbr\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003ch4\u003e\u003cspan class=\"\"\u003eApplications\u003c\/span\u003e\u003c\/h4\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eRecommended For\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eHigh-Output 21700 LED Flashlights\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Perfect for Fenix and other 21700-powered flashlights. The 4900mAh capacity provides near-flagship runtime—approximately 40% more energy than a standard 3500mAh 18650 cell. Ideal for everyday carry, professional use, and extended outdoor adventures.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eHeadlamps for Outdoor \u0026amp; Professional Use\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Extended runtime for camping, running, caving, and industrial applications. The protection circuit prevents over-discharge damage when lights are accidentally left on.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eCamping Lanterns \u0026amp; Emergency Lights\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Reliable power for extended trips and power outages. The 4900mAh capacity ensures lights stay on through the longest nights.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eBicycle Lights\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Consistent output for night riding, endurance events, and multi-day touring without battery changes.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eSmart Doorbells \u0026amp; Wireless Security Cameras (21700 Compatible)\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Ultra-long standby with reliable power for motion detection and recording events.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003ePortable Fans \u0026amp; Outdoor Gadgets\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Suitable for any 21700-powered device drawing under 10A where long runtime is desired.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eNot Recommended For\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eHigh-Power Vaping \/ Mechanical Mods\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: These require 15–35A unprotected cells. The 10A protection limit is insufficient for sub-ohm applications.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eCordless Power Tools\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Drills, saws, and impact drivers demand 20–40A continuous current, far beyond this battery's 10A protection limit.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eRC Cars, Drones \u0026amp; High-Drain Models\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: These require 20–30A+ continuous current. This battery will not function and may trigger protection.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003e18650-Only Devices\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: This is a 21700 cell (21mm diameter) and will not physically fit in 18650 battery compartments.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eMulti-Cell Series Packs\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Individual protection boards may conflict. Use matched unprotected cells with an external BMS instead.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003e\u003cspan class=\"\"\u003eFAQ\u003c\/span\u003e\u003c\/h4\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: How does the 4900mAh compare to 5000mAh cells? Is the difference noticeable?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: The ARB-L21-4900 provides 4900mAh, which is only about 2% less capacity than a 5000mAh cell. In real-world use, the difference is negligible—perhaps 5–10 minutes less runtime on high mode in a typical flashlight. For the vast majority of users, the practical runtime is essentially identical, often at a more attractive price point.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: Is this battery compatible with my Fenix 21700 flashlight?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: Yes. The ARB-L21-4900 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 length before ordering.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: Can I use this battery in my 18650 device?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: 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.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: What does \"protected\" mean and why should I choose a protected cell?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: A protected cell has a built-in circuit board that automatically prevents overcharge (above 4.2V), over-discharge (below 2.5V), short circuits, and excessive current draw (above 10A). This makes single-cell use significantly 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.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: Can I use this battery for vaping or power tools?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: No. Vaping devices and power tools require high continuous currents (typically 15–40A). The ARB-L21-4900'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.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: How should I charge and store this battery?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: 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 (2.45A) 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.\u003c\/span\u003e\u003c\/p\u003e","brand":"Fenix","offers":[{"title":"Default Title","offer_id":51454157652214,"sku":"OAS417","price":29.98,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0819\/2753\/6886\/files\/imagesfenix-21700-4900mah-button-top-main_514f2f9c-8c16-4d84-a39c-2b7d04c866fb.webp?v=1786965975","url":"https:\/\/oneandes.com\/products\/fenix-21700-rechargeable-battery-3-6volt-li-ion-batteries-4900mah-large-capacity-button-top-for-led-flashlight-headlamp","provider":"OneAndes","version":"1.0","type":"link"}