4000mAh (14.4Wh) 3.7V 18650 Rechargeable Li-ion Battery – Ultra High Capacity for Flashlights, Headlamps, Fans, Toys & Cameras

The Pinnacle of 18650 Capacity
When only the absolute maximum will do, this 4000mAh 18650 battery delivers. With 14.4 watt-hours of stored energy, it sits at the very summit of what a standard 18650 cell can offer — a full 100% more capacity than basic 2000mAh cells, and a solid step above even the popular 3500mAh class. It is engineered for people who refuse to compromise on runtime: the night hiker who needs a flashlight that lasts from dusk to dawn, the photographer who power a camera flash throughout a long shoot, the parent who wants a toy that won't die mid-play. This is the battery that finally makes “all-day power” a reality.

Unprotected, Uncompromised Design
We intentionally omitted the external protection PCB. The result is a cell that is shorter, lighter, and electrically purer. It measures as little as 65.2mm in the flat top version, slipping seamlessly into ultra-compact flashlights and devices that cannot fit a longer protected cell. Without the extra PCB resistance, energy flows directly from the high‑density NMC chemistry to your device, minimizing voltage sag and keeping things cool under load. Of course, this means the cell relies on you to pair it with a quality charger and a device that implements its own low‑voltage cutoff — a standard feature in virtually all modern enthusiast flashlights, USB fans, and smart electronics.

Your Terminal, Your Choice
Every device is different, so we provide both Button Top and Flat Top options. The Button Top has a raised positive nipple that locks securely into spring‑loaded contacts and sails past mechanical reverse‑polarity rings. The Flat Top features a totally flush positive end, essential for spot‑welding custom battery packs, power banks, and high‑performance flashlights with recessed pogo‑pin contacts. Simply check your device manual and pick the version that fits — no adapters, no frustration.

Where the 4000mAh Advantage Shines
This cell is rated for a continuous discharge of 5A, placing it firmly in the medium‑drain sweet spot. Inside a modern LED flashlight, you can expect over 4 hours of bright 300‑lumen light, or an entire night on a cozy low mode. A lightweight headlamp will run for an entire weekend of trail running or reading on a single charge. A portable fan can hum through a full workday on low, and motorized toys — RC cars, robots, action figures — keep running long after the competition’s batteries have given up. For camera users, this battery powers external flashes, portable field monitors, and battery grips that accept 18650 cells, giving you extra hundreds of shots without reaching for a spare.

Built to Endure, Designed to Protect
Under the nickel‑plated steel shell, advanced NMC chemistry delivers a stable 3.7V nominal voltage and a flat discharge curve. Your light stays bright, your motor keeps torque, and your camera doesn't unexpectedly power down. A built‑in PTC thermistor acts as a resettable current limiter, while a precision safety vent releases internal pressure should the cell ever be pushed beyond its limits. With a cycle life exceeding 500 full charges and ultra‑low self‑discharge, this 4000mAh workhorse will stay ready through months of storage and hundreds of recharge cycles. It is not just a battery; it is a long‑term power investment.

Key Features

• Class‑Leading 4000mAh (14.4Wh) Capacity
  Twice the energy of a 2000mAh cell, and significantly more than common 3500mAh options. Ideal for devices that must run for hours without interruption.

• Unprotected for Maximum Compatibility
  Shorter form factor (65.2mm flat / 66.8mm button) fits the tightest battery compartments. Lower overall resistance ensures efficient power delivery and minimal heat.

• Choose Your Terminal: Button Top & Flat Top
  Button Top for secure spring‑contact connections. Flat Top for spot‑welded packs and recessed-contact flashlights. True compatibility without compromise.

• Stable 3.7V NMC Chemistry
  Holds a flat discharge curve from 4.2V down to 2.5V. Your devices maintain constant brightness, speed, and performance.

• Very Low Internal Resistance (≤50mΩ)
  Minimizes voltage sag even under a continuous 5A load. At typical 1‑3A draws, the voltage drop is negligible, ensuring efficient energy extraction.

• 500+ Cycle Life & Negligible Self‑Discharge
  Recharge hundreds of times with minimal capacity loss. Stores for months at 3.6‑3.7V without significant drain — always ready for emergencies.

• Essential Passive Safety
  Integrated PTC thermistor and resealable pressure vent provide a first line of defense against overcurrent and extreme internal pressure. Nickel‑plated steel can resists corrosion and drops.

• Eco‑Friendly & Cost‑Effective
  One 4000mAh 18650 replaces hundreds of disposable alkaline batteries. Zero memory effect lets you recharge at any state of charge.

Technical Parameters

Applications

1. Ultimate Endurance Flashlights
Built for night hikers, security patrols, and search‑and‑rescue teams. The 4000mAh capacity provides over 4 hours on a 300‑lumen high, or a full night on low. Compatible with ZebraLight, Emisar, Convoy, and other unprotected‑cell torches that feature low‑voltage cutoff. Flat top fits ultra‑tight tubes; button top locks into spring‑loaded hosts.

2. Headlamps for Extended Use
Trail runners, backpackers, and mechanics will appreciate a headlamp that lasts the entire job or trip. At a typical 100‑lumen level, expect 8‑10 hours of continuous hands‑free light. The cell’s moderate weight keeps the headlamp balanced and comfortable.

3. Portable Fans & Camping Coolers
Keep the air moving all day long. A desk fan on low speed can run for 10‑13 hours, while high speed delivers 2.5‑4 hours of strong airflow. The flat top version is often required for recessed fan battery bays.

4. Motorized Toys & RC Vehicles
RC cars, robots, and action toys that draw 1‑3A run noticeably longer on 4000mAh. A single charge can power an entire afternoon of play, outperforming disposable alkaline batteries by a wide margin.

5. Camera Equipment & Accessories
Designed for professional accessories that accept standard 18650 cells: external flash battery packs, portable field monitors, video lights, and some camera battery grips. The ultra‑high capacity means more shots, longer recording sessions, and fewer battery swaps during a critical shoot. Always verify that your device supports unprotected 18650 cells and includes low‑voltage protection.

6. DIY Battery Packs & Power Banks
Flat top cells are tailor‑made for spot welding into 2S, 3S, or 4S configurations. Build a high‑capacity power bank, a portable Bluetooth speaker battery, or a backup supply for a drone ground station. The 4000mAh per cell maximizes energy density in compact builds.

7. Emergency & Backup Power
Store a few charged cells in a waterproof case for hurricanes, blackouts, or long‑term camping. Their low self‑discharge ensures they are ready when you need them most.

FAQ

Q1: Why is this battery unprotected?
A: Removing the protection PCB shortens the cell (fits more devices) and lowers internal resistance. However, it requires that you use a charger that stops at exactly 4.2V and only install it in devices that have their own low‑voltage cutoff (set typically below 3.0V). Almost all enthusiast flashlights, USB fans, and many camera accessories meet this requirement.

Q2: How do I choose between Button Top and Flat Top?
A: If your device has a spring at the positive end and a physical ring that prevents flat tops from contacting, choose Button Top. If the contacts are flat and the battery tube is extremely tight (or you’re building a spot‑welded pack), you need Flat Top. Always consult your device’s manual.

Q3: Can I use this battery in a camera that originally takes a proprietary battery?
A: Only if the camera or its accessory explicitly accepts standard 18650 cells. This battery is not a direct replacement for proprietary camera packs (e.g., Canon LP‑E6, Sony NP‑FZ100). It is designed for external accessories like flash power packs, monitors, and grips that have 18650 slots. Using it in an incompatible camera may cause damage.

Q4: What is the maximum current I can draw?
A: 5A continuous. This is sufficient for LED flashlights (even on turbo most single‑cell lights draw 3‑5A), small to medium fans, and most motorized toys. Do not use in sub‑ohm vaping devices, cordless power tools, or any application that demands more than 5A. For those, use a dedicated high‑rate IMR or INR cell.

Q5: How long does it take to charge?
A: At the standard charge rate of 2A, a full charge from empty takes approximately 2.5 hours. Using a 1A charger will take around 4.5 hours. Always use a quality Li‑ion charger with proper 4.2V termination.

Q6: How should I store this battery safely?
A: Keep it in a plastic battery case away from metal objects. For storage longer than one month, bring the voltage to 3.6–3.7V (roughly 50% charge). Check the voltage every 3 months and recharge if it falls below 3.0V. Never store a fully depleted cell.

Q7: Can I fly with this battery?
A: Yes. At 14.4Wh, it is well below the 100Wh IATA limit. Carry it in hand luggage, terminals insulated. Airlines permit multiple small cells for personal use.