Fenix ARB-L21-5800 21700 5800mAh 10A 3.6V Button Top Protected Battery – Max Capacity for Flashlights & Headlamps
Description
Description
Maximize your runtime to the absolute limit with the genuine Fenix ARB-L21-5800, the highest-capacity 21700 battery in Fenix's lineup. Built around an ultra-high-capacity 5800mAh cell core, this protected button top battery delivers approximately 16% more runtime than standard 5000mAh 21700 cells—making it the ultimate power solution for extended missions, multi-day adventures, and professional applications where changing batteries is inconvenient or impossible. 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. For users who refuse to compromise on runtime, the ARB-L21-5800 is the undisputed endurance champion.
Key Features
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5800mAh Maximum 21700 Capacity – The highest capacity battery in the Fenix 21700 lineup. Provides approximately 16% more runtime than 5000mAh cells and about 65% more energy than a standard 3500mAh 18650.
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10A Continuous Discharge – Delivers stable, reliable power for demanding LED flashlights and outdoor equipment. Enough current for turbo modes and high-output settings without triggering protection.
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Built-in Protection Circuit – Safeguards against overcharge (4.2V cutoff), over-discharge (2.5V cutoff), short circuits, and overcurrent (10A limit), ensuring safe operation and protecting your valuable devices.
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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 a premium 21700 cell core and advanced protection circuitry for consistent, safe performance in demanding applications.
Parameters
| Parameter | Specification |
|---|---|
| Model | Fenix ARB-L21-5800 |
| Battery Type | 21700 Button Top Protected Lithium-Ion |
| Typical Capacity | 5800 mAh (0.2C discharge to 2.5V) |
| Minimum Capacity | ~5700 mAh |
| Nominal Voltage | 3.6 V (typical operating 3.7 V) |
| Max Continuous Discharge | 10 A (limited by built-in protection circuit) |
| Protection Functions | Overcharge (4.2V cutoff), Over-discharge (2.5V cutoff), Short Circuit, Overcurrent |
| Discharge Cut-off Voltage | 2.5 V (automatic protection cutoff) |
| Standard Charge | CC-CV, 0.5C (2900 mA) to 4.2 V, cut-off 50 mA (use a quality Li-ion charger) |
| Internal Resistance | Approx. 40–60 mΩ (including protection circuit and button top) |
| Cycle Life | ≥ 500 cycles (to 80% capacity) |
| Operating Temperature (Discharge) | -20°C to 60°C |
| Top Type | Button Top |
| Dimensions | Approx. 21.5 mm diameter × 71.5 mm length (~1–2mm longer than standard unprotected 21700) |
| Weight (single cell) | Approx. 73 g |
| Package Includes | 1 × Fenix ARB-L21-5800 protected button top battery |
Applications
Recommended For
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High-Output 21700 LED Flashlights: Perfect for Fenix and other 21700-powered flashlights. The 5800mAh capacity delivers the longest illumination time available in a protected 21700 cell—ideal for search and rescue, professional inspection, and extended outdoor expeditions.
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Headlamps for Professional & Outdoor Use: Designed for cave exploration, long-distance trail running, industrial inspection, and multi-day camping. The protection circuit prevents over-discharge damage during extended use.
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Camping Lanterns & Emergency Lights: Reliable power for extended power outages and off-grid living. The 5800mAh capacity ensures lights stay on through the longest nights.
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Bicycle Lights for Ultra-Endurance: Perfect for 24-hour races, multi-day bikepacking, and long-distance touring. Single-cell runtime covers entire events without battery changes.
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Smart Doorbells & Wireless Security Cameras (21700 Compatible): Months of standby time with reliable power for motion detection and recording events.
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Search & Rescue Equipment: When missions extend beyond expected timeframes, the extra 800mAh over standard 5000mAh cells provides a critical safety margin.
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Portable Fans & Outdoor Gadgets: Suitable for any 21700-powered device drawing under 10A where maximum runtime is the priority.
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: Is 5800mAh the real capacity? How much more runtime does it give compared to 5000mAh?
A: Yes. The ARB-L21-5800 uses an ultra-high-capacity 21700 cell core that delivers a true 5800mAh under standard test conditions. Compared to a 5000mAh 21700 cell, this provides approximately 16% more runtime. In a typical flashlight on high mode, this could mean an extra 30–45 minutes of illumination. Compared to a 3500mAh 18650, it offers about 65% more energy.
Q: Is this battery compatible with my Fenix 21700 flashlight?
A: Yes. The ARB-L21-5800 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 71.5mm long. Most 21700 flashlights are designed to accommodate protected cells, but please verify your device's battery compartment length 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 does it matter?
A: 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 (71.5mm 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-L21-5800'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 (2.9A) 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.
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
Maximum capacity with Fenix protection and 10A drain. The ultimate 21700 for flashlights.
My security flashlight runs on this 5800mAh. I get two full shifts on medium without recharging.
If you need the most runtime possible, this Fenix 5800 is the answer. Reliable and long-lasting.
The 5800mAh in a standard 21700 size is impressive. Same great protection circuit.
After 100 cycles, still holding 5600mAh. The button top shows no wear.
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.