{"product_id":"fenix-usb-type-c-21700-charger-genuine-arb-l21-4900u-usb-rechargeable-3-6v-battery-100-real-4900mah-high-capacity-button-top","title":"Fenix ARB-L21-4900U 21700 4900mAh 8A 3.6V USB-C Rechargeable Battery Button Top – Built-in Charging Port for Flashlights \u0026 Headlamps","description":"\u003ch4\u003e\u003cspan class=\"\"\u003eDescription\u003c\/span\u003e\u003c\/h4\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cspan class=\"\"\u003eSimplify your power routine with the genuine Fenix ARB-L21-4900U, a 21700 battery featuring a built-in USB-C charging port. No dedicated charger needed—just plug any USB-C cable directly into the battery and recharge from a wall adapter, power bank, car charger, or laptop. Built around a premium 4900mAh cell core, it delivers near-flagship runtime with integrated overcharge, over-discharge, and short-circuit protection. The button top design ensures broad compatibility with Fenix and most other 21700 flashlights. With a convenient LED charging indicator and excellent cycle life, the ARB-L21-4900U keeps your gear ready to go wherever a USB-C cable is available.\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=\"\"\u003eBuilt-in USB-C Charging Port\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Recharge directly from any standard USB-C power source. No external 21700 charger required. USB-C offers reversible plugging and improved durability over older connector types.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003e4900mAh High Capacity\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Provides near-flagship runtime for demanding LED flashlights, headlamps, and outdoor gear. Only slightly less than 5000mAh cells at a more accessible 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=\"\"\u003eIntegrated Safety Protection\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Built-in circuit guards against overcharge (4.2V), over-discharge (2.5V), short circuit, and overcurrent (8A limit), ensuring safe operation in any compatible device.\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.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eLED Charging Indicator\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e – Built-in LED shows charging status at a glance: red means charging, green means fully charged and ready to use.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eGenuine Fenix 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 long service life and 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-L21-4900U\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 with USB-C Charging\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=\"\"\u003e8 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=\"\"\u003eUSB-C Charging Input\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eUSB Type-C port, 5V \/ 1–2A recommended\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eCharging Indicator\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eBuilt-in LED (Red = Charging, Green = Fully Charged)\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=\"\"\u003eInternal Resistance\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003eApprox. 50–70 mΩ (including protection circuit and USB module)\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=\"\"\u003eCharging Temperature\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"\"\u003e0°C to 45°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 × 75.5 mm length (~5–6mm 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. 73 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-L21-4900U USB-C rechargeable 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 excellent runtime, and USB-C allows convenient recharging from any modern USB source—no separate charger to carry.\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: Ideal for camping, running, caving, and industrial work. The protection circuit prevents over-discharge damage, and USB-C enables easy field recharging from a power bank.\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: Any USB-C power source becomes your charger. The 4900mAh capacity ensures lights stay on through extended power outages.\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. Recharge between rides using the same USB-C cable you use for your phone or bike computer.\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: Extended runtime between charges. USB-C port allows easy periodic recharging without removing the battery from the mounting bracket.\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; Travel Gadgets\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: Minimize accessories—one USB-C cable charges your phone and your spare batteries.\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 8A 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 8A 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=\"\"\u003eUltra-Compact Flashlights with Tight Battery Tubes\u003c\/span\u003e\u003c\/strong\u003e\u003cspan class=\"\"\u003e: This battery measures approximately 75.5mm in length due to the USB-C port and protection circuit. Some flashlights with very tight battery compartments may not close fully. Always verify fit before ordering.\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 and USB modules 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 do I charge this battery? Is a special charger required?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: No special charger needed. Simply connect a standard USB-C cable to the port on the battery and plug the other end into any 5V USB power source—a phone charger, power bank, laptop, or car adapter. The built-in LED glows red during charging and turns green when fully charged. A full charge takes several hours depending on the power source.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: Will this fit my 21700 flashlight?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: It fits most 21700 flashlights that accept button top cells. Due to the integrated USB-C charging port and protection circuit, this battery is approximately 75.5mm long—about 5–6mm longer than a standard unprotected 21700 (70mm). Most 21700 flashlights with spring-loaded contacts can accommodate this extra length, but some ultra-compact models may not close fully. Please measure your device's battery tube or check the manufacturer's specifications before ordering.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: Can I also charge this battery in a regular 21700 charger?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: Yes. The ARB-L21-4900U can be charged either through its built-in USB-C port or in any standard 21700 Li-ion charger that accepts button top cells. Both methods are safe and fully supported.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: Is this battery suitable 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-L21-4900U's protection circuit limits output to approximately 8A. Using it in such devices will cause the protection to cut off power or may damage the battery. For these applications, use dedicated high-drain unprotected cells.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: How does the 4900mAh compare to the 5000mAh version?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: The ARB-L21-4900U 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. Many users find the USB-C convenience far outweighs this tiny capacity difference.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"ds-markdown-paragraph\"\u003e\u003cstrong\u003e\u003cspan class=\"\"\u003eQ: How should I store this battery long-term?\u003c\/span\u003e\u003c\/strong\u003e\n\u003cbr\u003e\u003cspan class=\"\"\u003eA: 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, as this accelerates capacity loss. The built-in USB-C port makes it easy to top up before use after storage.\u003c\/span\u003e\u003c\/p\u003e","brand":"Fenix","offers":[{"title":"Default Title","offer_id":51454157717750,"sku":"OAS416","price":31.98,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0819\/2753\/6886\/files\/imagesfenix-arb-l21-4900u-usb-21700-battery-main_2b85b85a-88c6-4c39-be9d-91bb97136a25.webp?v=1786965977","url":"https:\/\/oneandes.com\/products\/fenix-usb-type-c-21700-charger-genuine-arb-l21-4900u-usb-rechargeable-3-6v-battery-100-real-4900mah-high-capacity-button-top","provider":"OneAndes","version":"1.0","type":"link"}