Fenix ARB-L21-5000U 21700 5000mAh USB-C Rechargeable Battery Button Top – Protected Cell with Power Bank Output for Flashlights & Headlamps
Description
Description
The Fenix ARB-L21-5000U is a revolutionary 21700 battery that combines massive 5000mAh capacity with a built-in USB-C charging and discharging port. Unlike ordinary rechargeable cells, it can act as an emergency power bank to charge your phone, headlamp, or other USB devices directly—no separate charger required for the battery itself, and no separate power bank needed in a pinch. The integrated protection circuit guards against overcharge, over-discharge, and short circuits, while the button top design ensures broad compatibility with 21700 flashlights. With 5000mAh of energy and dual-role versatility, it is the ultimate all-in-one power solution for outdoor adventures, travel, and emergency preparedness.
Key Features
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5000mAh High Capacity – One of the highest capacities in the 21700 form factor, providing exceptionally long runtime for high-output LED flashlights and headlamps.
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Built-in USB-C Two-Way Charging – Input: Recharge the battery from any USB-C source (wall adapter, power bank, car charger). Output: Use the battery as an emergency power bank to charge your phone, GPS, or other small devices.
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Integrated Safety Protection – Built-in circuit prevents overcharge, over-discharge, short circuits, and overcurrent, ensuring safe, worry-free operation.
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Button Top Design – Raised positive terminal ensures reliable contact in Fenix and most other 21700 flashlights and devices.
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LED Power Indicator – Built-in LED shows remaining power level and charging status, so you always know when to recharge.
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Genuine Fenix Quality – Premium 21700 cell core with rigorous manufacturing standards for consistent performance and long service life.
Parameters
| Parameter | Specification |
|---|---|
| Model | Fenix ARB-L21-5000U |
| Type | 21700 Button Top Protected Battery with USB-C Power Bank Output |
| Typical Capacity | 5000 mAh (0.2C discharge to 2.5V) |
| Nominal Voltage | 3.6 V (typical operating 3.7 V) |
| Max Continuous Discharge | ~8 A (limited by built-in protection circuit) |
| Protection Functions | Overcharge, Over-discharge, Short Circuit, Overcurrent |
| USB-C Input (Charging) | 5V / 1–2A |
| USB-C Output (Power Bank) | 5V / 1–2A (supports charging small USB devices like phones, GPS, headlamps) |
| Discharge Cut-off Voltage | 2.5 V (automatic protection cutoff) |
| Cycle Life | ≥ 500 cycles (to 80% capacity) |
| Operating Temperature | -20°C to 60°C (discharge); 0°C to 45°C (charge) |
| Top Type | Button Top |
| Dimensions | Approx. 21.5 mm diameter × 76 mm length (~6mm longer than standard unprotected 21700) |
| Weight | Approx. 73 g |
| Package Includes | 1 × Fenix ARB-L21-5000U USB-C rechargeable battery |
Applications
Recommended For
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High-Output 21700 LED Flashlights – Perfect for Fenix and other 21700-powered flashlights. The 5000mAh capacity ensures extremely long illumination time, while USB-C charging allows convenient recharging anywhere.
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Headlamps (21700 Compatible) – Extended runtime for professional, industrial, or outdoor use. The protection circuit prevents over-discharge damage.
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Emergency Power Bank Use – In a pinch, use the battery to charge your phone, GPS device, or secondary headlamp directly via USB-C cable. An essential backup for outdoor adventures and emergencies.
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Camping Lanterns & Outdoor Gear – Massive capacity keeps your campsite illuminated all night, with the added bonus of emergency device charging.
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Travel & Everyday Carry – One device serves as both a flashlight battery and a backup power bank, reducing the gear you need to carry.
Not Recommended For
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High-Drain Vaping / Mechanical Mods – Requires 15–35A unprotected cells. The protection circuit limits output to ~8A.
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Cordless Power Tools – Require 20–40A continuous current.
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Devices Requiring Flat Top 21700 Cells – This is a button top cell. Verify compatibility.
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Ultra-Compact Flashlights – The built-in USB-C port and protection circuit increase length to ~76mm. Ensure your device can accommodate this before purchasing.
FAQ
Q: Can this battery really charge my phone?
A: Yes. The ARB-L21-5000U features a two-way USB-C port. When connected to a USB device, it can output power to charge phones, GPS units, secondary headlamps, and other small USB-powered gadgets. Note that the output is 5V/1–2A, providing emergency top-up power. It is not intended to replace a dedicated high-capacity power bank for full daily phone charging.
Q: How do I charge this battery?
A: Use any standard USB-C cable connected to a 5V USB power source (phone charger, power bank, laptop, or car adapter). The built-in LED indicator shows the charge status. A full charge takes several hours depending on the power source.
Q: Will this fit my 21700 flashlight?
A: It fits most 21700 flashlights that accept button top cells. Due to the integrated USB-C port and protection circuit, this battery is approximately 76mm long—about 6mm longer than a standard unprotected 21700 (70mm). Some compact flashlights with tight battery compartments may not close completely. Please check your device’s battery tube length before ordering.
Q: Is this battery suitable for vaping or power tools?
A: No. Vaping devices and power tools require high continuous currents (15–40A). The ARB-L21-5000U’s protection circuit limits output to approximately 8A. For those applications, use dedicated high-drain unprotected cells.
Shipping and Returns
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Free Shipping: Enjoy free shipping on all orders over $65. For orders under $65, the shipping cost is $8.99.
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Delivery Time: Once shipped, orders typically arrive within 7–15 business days.
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Easy Returns: We want you to be completely satisfied. If you're not, you can return your product within 30 days of receiving your order. Please ensure the items are unused and in their original condition. For return instructions, please contact our support team.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
Security
This Fenix battery replaced my separate power bank and spare batteries. One cell to rule them all.
The versatility of this battery justifies the price. Flashlight battery and emergency charger in one.
I trust this Fenix battery for search and rescue. The power bank feature has saved me twice.
Fenix combined high capacity, protection, and power bank output in one cell. Nothing else compares.
My video doorbell runs on this 21700. The USB-C port means I can charge it in place.
Refund Policy
OneAndes Return & Refund Policy
At OneAndes, we are committed to providing high-quality cylindrical lithium-ion batteries for your drones, vacuums, garden tools, and other power needs. If you are not completely satisfied with your purchase, we are here to help. Please read our full return policy below before initiating a return.
1. Return Window
You have 30 calendar days from the date you received your item(s) to request a return. Any return request submitted after 30 days will not be eligible for a refund or exchange.
2. Eligibility Conditions
To qualify for a return, all items must meet the following conditions:
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Condition: Items must be unused, undamaged, and in the same condition that you received them.
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Packaging: Items must be returned in their original packaging with all accessories, manuals, and protective covers intact.
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Proof of Purchase: A valid receipt, order confirmation email, or proof of purchase must accompany all returns.
Non-Returnable Items:
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Batteries that have been installed, used, or show any signs of wear.
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Items marked as “Final Sale” or “Clearance” at the time of purchase.
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Customized or special-order products.
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Gift cards.
If a returned item fails to meet these conditions, we reserve the right to deny the return or charge a restocking fee.
3. How to Initiate a Return
Follow these steps to return your product:
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Contact Us: Email our support team at support@oneandes.com with your order number and the reason for return. We aim to respond to all return requests within 24 hours on business days.
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Receive RMA: We will provide you with a Return Merchandise Authorization (RMA) number and return instructions. Do not ship any item without an RMA number.
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Pack Securely: Place the item in its original packaging, include all accessories, and clearly write the RMA number on the outside of the box.
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Ship to Our US Warehouse: Ship the package to the following address:
OneAndes Returns
10320 6th St
Rancho Cucamonga, CA 91730
USA*Important: Lithium-ion batteries are classified as hazardous materials (Class 9). Please follow the shipping guidelines provided in Section 4 below. We recommend using a trackable shipping service and purchasing shipping insurance, as we cannot guarantee receipt of your returned item.*
4. Return Shipping Costs
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Defective or Incorrect Items: If the item you received is defective, damaged in transit, or different from what you ordered, OneAndes will cover the return shipping cost. In this case, we will provide you with a prepaid return shipping label.
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Buyer’s Remorse / Non-Defective Returns: If you are returning an item for any other reason (e.g., no longer needed, ordered the wrong model), you are responsible for the return shipping costs. You must prepay the return shipping cost using a trackable carrier that accepts lithium batteries. We do not provide prepaid return labels for non-defective returns.
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Lithium Battery Shipping Regulations: By law, all returns must be shipped in compliance with applicable dangerous goods regulations. We will provide guidance on proper packaging and labeling. Failure to comply may result in carrier refusal, seizure, or additional fees. We are not responsible for returned items lost or rejected by the carrier due to improper shipping.
5. Refunds
Once we receive and inspect your return at our Rancho Cucamonga, CA facility, we will notify you via email of the approval or rejection of your refund.
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Approved Refunds: If approved, your refund will be processed to your original method of payment within 5 to 10 business days. Please note that depending on your bank or credit card issuer, it may take additional time for the credit to appear on your statement.
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Partial Refunds: In certain situations, only partial refunds may be granted:
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Items not in original condition, missing parts, or damaged for reasons not due to our error.
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Items returned more than 30 days after delivery (reviewed on a case-by-case basis).
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Non-Refundable Fees: Original shipping charges are non-refundable unless the return is due to our error (defective product or incorrect shipment).
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Restocking Fee: We do not charge a restocking fee for defect-free returns, but we may deduct the return shipping cost, which will be deducted from your refund.
6. Exchanges
We replace items only if they are defective or damaged upon arrival. If you need to exchange a defective item for the same product, please contact us at support@oneandes.com. Exchanges are subject to product availability.
If you ordered the wrong battery size or model, please follow the standard return process above and place a new order for the correct item.
7. Damaged or Missing Items
If your package arrives visibly damaged, please take photos of the package before opening and contact us immediately. We will work with the shipping carrier to file a claim and arrange for a replacement or refund. Damaged or missing item claims must be reported within 7 calendar days of delivery. For immediate assistance, you may also call us at (213) 316-8849.
8. Order Cancellation
You may cancel your order without penalty if it has not yet been shipped. To cancel, email us at support@oneandes.com as soon as possible. If the order has already been processed or shipped, you will need to follow the standard return process upon receipt.
9. Warranty
All OneAndes batteries are backed by a 12-month limited warranty against defects in materials and workmanship. This warranty does not cover damage caused by misuse, improper charging, unauthorized modifications, normal wear and tear, or use outside of manufacturer specifications. For warranty claims, please contact our support team.
10. Contact Us
If you have any questions about our Return & Refund Policy, please reach out:
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Email: support@oneandes.com
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Phone: (213) 316-8849 (Mon-Fri, 9 AM – 5 PM Pacific Time)
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Mailing Address: 10320 6th St, Rancho Cucamonga, CA 91730, USA
We aim to respond to all inquiries within 24 hours during business days. Please include your order number for faster assistance.