The 21700 Power Revolution in Your Hands
Step into the next generation of portable power with the EVE INR21700-50E. This cell represents the evolution beyond the ubiquitous 18650: a 21mm diameter, 70mm length form factor that packs 5000mAh of genuine capacity — roughly 2.5 times what a standard 18650 can hold. Whether you're feeding a high‑performance LED flashlight, a portable fan that runs all day, a camera rig that can't afford to die mid‑shoot, a child's ride‑on toy, or a surveillance camera guarding your property, this battery delivers dependable, long‑lasting energy that simply outclasses smaller cells.
10A Continuous Discharge — Honest Power, No Exaggeration
The INR21700-50E is rated for a true 10A continuous discharge current. This isn't a marketing number; it's the cell's verified capability, making it perfectly suited for medium‑drain applications that demand sustained current without voltage collapse. Flashlights running on high mode, brushless camera gimbals, motorized toys, and security cameras with infrared night vision all benefit from the stable 3.7V output that holds its ground even under load. The cell can pulse up to 15A for short bursts, providing extra headroom when your device needs a momentary surge. We don't claim 15A continuous — we give you the real spec so you can trust what you're buying.
Unprotected by Design — Pure, Direct Energy
Like all high‑performance cylindrical cells, the 50E is supplied without an external protection PCB. This keeps the cell length at a standard 70mm — essential for fitting into the precisely machined battery tubes of modern flashlights, camera battery holders, and device sleds. Removing the PCB also slashes internal resistance, allowing the 10A current to flow with minimal heat generation. Of course, this requires you to use a quality charger that terminates at exactly 4.2V and to only install the cell in devices with their own built‑in low‑voltage cutoff. Almost every LED flashlight, USB‑rechargeable fan, camera accessory, and smart surveillance device on the market today already incorporates this protection, making them ideal partners for this bare cell.
Three Terminal Options — Your Device, Your Choice
Unlike many suppliers who only offer one configuration, we provide three distinct positive terminal styles so you can select the exact fit your device demands:
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Button Top: A raised positive nipple (~1.5mm protrusion). This locks securely into spring‑loaded battery compartments and passes mechanical reverse‑polarity guards easily. Ideal for many consumer flashlights, fans, and toy battery trays that rely on a spring‑based positive contact.
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Flat Top: A completely flush positive terminal. This is required for devices with ultra‑tight battery tubes, for series/parallel pack building where cells are stacked end‑to‑end, and for gadgets with pogo‑pin or recessed flat PCB contacts. Many high‑end flashlights (ZebraLight, Emisar, Noctigon, etc.) specifically require flat top cells.
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Nickel Tab: Both positive and negative terminals come pre‑welded with nickel strips. This is the go‑to option for building custom battery packs, power banks, e‑bike modules, and any application where you plan to spot‑weld the cell into a permanent configuration. The tabs are professionally attached and ready for soldering or additional welding.
Where 5000mAh Transforms Your Experience
Let's put that 5000mAh into perspective. In a single‑cell LED flashlight on a medium 300‑lumen setting, you can expect over 5 hours of continuous light. On a low 50‑lumen mode, this cell can illuminate an entire night — 10+ hours — without a swap. A portable USB fan on low speed will spin for 12–14 hours, keeping your desk, tent, or workshop comfortable through multiple shifts. A wireless surveillance camera running on motion‑detection can last weeks or even months between charges, dramatically reducing maintenance. And in a child's ride‑on toy or RC vehicle, the extended runtime means longer play sessions and fewer frustrated kids. This is the battery that finally lets you stop carrying spares for everything.
Premium INR Chemistry for Long Life
The "INR" designation indicates a Nickel‑Manganese‑Cobalt (NMC) chemistry optimized for both energy density and power delivery. It offers better thermal stability than older ICR cells, a longer cycle life, and lower internal resistance. Speaking of cycle life: the 50E is rated for over 500 full charge/discharge cycles while retaining ≥70% of its original capacity. With low self‑discharge, you can store a spare for months at the recommended storage voltage (3.6–3.7V), and it will still wake up with most of its charge intact. The steel can is nickel‑plated for corrosion resistance and mechanical durability — it can handle the bumps and drops of real‑world use without complaint.
Safety Without the PCB
Despite the lack of an external protection IC, the 50E includes several built‑in safety features. A PTC thermistor increases internal resistance if the cell overheats, limiting current and preventing thermal runaway. A resealable pressure vent integrated into the positive cap will rupture safely if internal gas pressure ever reaches a dangerous level. A CID (Current Interrupt Device) physically disconnects the internal electrode if pressure continues to rise beyond the vent's capacity. These three layers of passive protection provide peace of mind, provided you handle the cell responsibly: don't short‑circuit it, don't expose it to fire or water, and always use a quality charger.
Key Features
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Genuine 5000mAh Capacity
Class‑leading energy density in the 21700 form factor. Delivers over 5 hours of 300‑lumen flashlight light, 12–14 hours of fan operation, or weeks of surveillance camera standby on a single charge.
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True 10A Continuous Discharge
Verified 10A continuous current output — not an inflated marketing claim. Handles sustained medium‑drain loads with minimal voltage sag. Pulses up to 15A for short bursts.
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Unprotected Bare Cell Design
Standard 70mm length fits all 21700‑compatible devices. Lower internal resistance allows efficient power delivery and cooler operation. Requires a 4.2V Li‑ion charger and device with low‑voltage cutoff.
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Three Terminal Variants: Button Top, Flat Top & Nickel Tab
Button Top for spring‑loaded compartments. Flat Top for tight tubes and pogo‑pin contacts. Nickel Tab for spot‑welded DIY battery packs. Choose the exact style your project demands.
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Premium INR Chemistry
Nickel‑Manganese‑Cobalt (NMC) formulation offers superior thermal stability, higher energy density, and longer cycle life compared to older ICR chemistries.
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Low Internal Resistance (≤25mΩ)
Minimizes voltage drop under load. At 10A discharge, the voltage sags by only 0.25V, keeping your devices in regulation and your beams bright.
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500+ Cycle Life & Low Self‑Discharge
Over 500 full charge/discharge cycles with ≥70% capacity retention. Stores for months at 3.6–3.7V without significant power loss.
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Multi‑Layered Passive Safety
Built‑in PTC thermistor, resealable pressure vent, and CID (Current Interrupt Device) provide three levels of protection against over‑temperature and over‑pressure.
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Nickel‑Plated Steel Can
Corrosion‑resistant, drop‑resistant, and built to handle the rigors of daily use, outdoor adventures, and workshop environments.
Technical Parameters
Applications
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High‑Performance LED Flashlights
Many modern enthusiast lights (Noctigon DM11, Convoy M21 series, Wurkkos TS21, Sofirn IF22A) are designed specifically for the 21700 format. The 5000mAh capacity provides over 5 hours of 300‑lumen medium light, or an entire night on low. The flat top is often required for tight‑fitting hosts; the button top secures in spring‑loaded tubes. If you're building a custom light, the nickel tab option simplifies wiring.
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Portable Fans & Cooling Devices
USB‑rechargeable camping fans, job site fans, and personal coolers that accept a 21700 will run markedly longer than with an 18650. Expect 12–14 hours of low‑speed breeze or 3–4 hours of high‑speed airflow per charge. The button top fits most consumer fan compartments; flat top suits recessed bays.
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Camera Equipment & Accessories
External monitor/recorder battery plates, LED video light panels, and some camera grips now accept 21700 cells. The 10A continuous discharge is well‑suited for powering field monitors and LED arrays, and the 5000mAh means fewer battery swaps during a long shoot. Verify your equipment's required terminal type — many use flat top.
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Motorized Toys & Ride‑Ons
Power wheels, RC trucks, and toy robots that have been upgraded to Li‑ion often benefit from the 5000mAh capacity. In a 2S or 3S configuration, runtime extends dramatically compared to stock lead‑acid or small 18650 packs. The nickel tab variant is perfect for building custom welded packs.
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Surveillance & Security Devices
Wireless outdoor cameras, trail cameras, and motion‑sensor lights that use removable 21700 cells can run for weeks or months on a single charge. The low self‑discharge means the battery stays ready during long idle periods. Flat top is commonly required for camera battery cradles.
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DIY Battery Packs & Power Banks
The nickel tab option is purpose‑built for spot‑welders and hobbyists. Build a 2S2P pack for a portable Bluetooth speaker, a 3S pack for a drone ground station, or a high‑capacity USB‑C power bank. The EVE 50E cells are known for consistent capacity, making cell matching straightforward.
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Portable Radios & Communication Gear
Ham radio handhelds, emergency radios, and portable PA systems that accept 21700 batteries benefit from the massive capacity. A single charge can power a receiving radio for days, making it ideal for camping, disaster preparedness, and field operations.
FAQ
Q1: Is this cell really 5000mAh? That seems high.
A: Yes, 5000mAh is the genuine capacity of the EVE INR21700-50E. The larger 21700 form factor (21mm × 70mm vs 18mm × 65mm) provides significantly more internal volume for electrode material, enabling this class‑leading capacity. You can verify it with any analyzing charger.
Q2: Can this battery really deliver 15A? I saw a listing that said 15A.
A: The cell is rated for 10A continuous discharge and can handle 15A pulses (under 3 seconds). Some listings may advertise "15A" without specifying it's a pulse rating. We disclose the honest continuous rating so you can make an informed purchase. If you need a 21700 that handles 15A+ continuously, we recommend the Samsung 40T or Molicel P42A.
Q3: Why is this battery unprotected? Is it safe?
A: Removing the protection PCB keeps the cell at standard 70mm length and reduces internal resistance. It's completely safe when used correctly: always charge with a quality 4.2V Li‑ion charger, and only use it in devices with built‑in low‑voltage cutoff (almost all modern flashlights, cameras, fans, and surveillance gear have this). The cell itself includes a PTC thermistor, safety vent, and CID for passive protection.
Q4: Which terminal should I choose — Button Top, Flat Top, or Nickel Tab?
A: Button Top for devices with spring‑loaded positive contacts and a physical reverse‑polarity ring. Flat Top for tight battery tubes and pogo‑pin/flat PCB contacts (common in enthusiast flashlights). Nickel Tab if you're building a spot‑welded battery pack, power bank, or custom project. If you're unsure, measure your device's battery compartment or consult its manual.
Q5: Will this fit in a device designed for 18650?
A: No. A 21700 cell has a 21mm diameter and 70mm length, while an 18650 is 18mm × 65mm. The 21700 is wider and slightly longer. Your device must explicitly support the 21700 format. Using an adapter or forcing the cell into an 18650 tube can damage the device and the battery.
Q6: How long will a 5000mAh battery run my portable fan?
A: On low speed (drawing about 0.4–0.5A), approximately 10–12 hours. On high speed (about 1.5–2A), around 3–4 hours. The 5000mAh capacity is nearly 2.5 times a 2000mAh 18650, so you'll notice a dramatic runtime improvement.
Q7: How should I store this cell when not in use?
A: Keep it in a plastic battery case or silicone sleeve, away from metal objects and moisture. For storage longer than one month, bring the voltage to about 3.6–3.7V (roughly 50% charge). Check every 3 months and recharge if it drops below 3.0V. Never store a fully depleted cell.
Q8: Can I charge this battery with my existing 18650 charger?
A: Only if your charger explicitly supports 21700 cells. The 21700 is both wider and slightly longer than an 18650. Many modern chargers from brands like XTAR, Nitecore, and LiitoKala do support 21700s — check your charger's specifications. If your charger's bay is too tight or too short, do not force the cell in.
Q9: Can I fly with this battery?
A: Yes. 5000mAh at 3.7V equals 18.5Wh, which is well under the 100Wh IATA limit for carry‑on luggage. Carry the cell in your hand luggage, terminals insulated with tape or a case. Airlines typically permit multiple small lithium cells for personal use.
Q10: What's the difference between INR and ICR chemistry?
A: INR (Lithium Nickel Manganese Cobalt Oxide) offers better thermal stability, higher discharge rates, and longer cycle life compared to older ICR (Lithium Cobalt Oxide) cells. INR is the preferred chemistry for modern high‑capacity cells like the EVE 50E.
