2500mAh (9.25Wh) 3.7V 18650 Rechargeable Li-ion Battery (2-Pack) – for Flashlights, Headlamps, Mini Fans & Solar Lights

Double the Power, Double the Convenience
Why settle for a single battery when you can have a ready‑to‑swap pair? This 2‑pack of 2500mAh 18650 cells ensures that while one battery powers your flashlight, headlamp, mini fan, or solar garden light, the other sits fully charged and waiting. Each cell stores a genuine 9.25 watt‑hours of energy — a solid 25% more than a standard 2000mAh battery — giving your everyday devices noticeably longer runtimes without the weight penalty of larger 3500mAh cells.

Unprotected, Uncompromising, and Ultra‑Compatible
We intentionally leave the external protection PCB off these batteries. The result is a cell that stays as short as 65.0mm (flat top) or 66.5mm (button top), slipping effortlessly into devices that refuse even a millimeter of extra length. The absence of a protection board also strips away an extra layer of electrical resistance, so more of the battery’s energy reaches your device, and less is wasted as heat. Naturally, this design expects you to use a quality charger that stops at exactly 4.2V, and to only install the cell in devices with built‑in low‑voltage cutoff. The vast majority of modern LED flashlights, USB‑rechargeable fans, headlamps, and solar light controllers already include this protection, making them ideal partners.

Choose Your Terminal: Button Top or Flat Top
Compatibility doesn’t have to be a guessing game, so this 2‑pack is available with both positive terminal styles. The Button Top version has a raised positive nipple (~1.5mm) that locks firmly into spring‑loaded compartments and clears mechanical reverse‑polarity rings. The Flat Top version features a completely flush positive end — essential for ultra‑tight flashlight tubes, for building spot‑welded DIY battery packs, and for devices with pogo‑pin or flat PCB contacts. Simply pick the variant your equipment requires, and enjoy a snug, reliable connection every time.

Where 2500mAh Makes the Difference
Each battery in this pack is rated for a continuous discharge of up to 5A, perfectly matching the needs of medium‑drain electronics. Inside a compact EDC flashlight, expect around 2.5 hours of bright 300‑lumen output, or over 8 hours on a gentle low mode. A lightweight headlamp will easily last through a full night of reading, camping, or trail running on a single charge. A USB mini fan will hum on low speed for 6–8 hours, keeping you cool through a workday or a hot summer night. And in solar‑powered garden lights, the 2500mAh capacity stores ample daytime sun to illuminate pathways, flowerbeds, or patios from dusk until well past midnight — far outlasting the smaller 1200–1500mAh cells often bundled with these fixtures.

Built to Last, Designed for Safety
Under the nickel‑plated steel shell, advanced NMC chemistry holds a steady 3.7V nominal voltage and an impressively flat discharge curve. Your light doesn’t dim, your fan doesn’t slow, and your solar light stays bright until the battery is nearly empty. Despite the unprotected design, each cell incorporates a PTC thermistor that suppresses over‑current spikes and a resealable safety vent that releases pressure under extreme abuse. With a cycle life of over 500 full charges and very low self‑discharge, you can keep one cell in your device and the spare in a drawer for months — it will still be ready when the first one runs out. This 2‑pack replaces hundreds of disposable alkaline batteries over its lifespan, making it a wallet‑friendly and eco‑conscious choice.

Key Features

• 2‑Pack Value Set
  Two identical 2500mAh cells. Always keep a fully charged spare — ideal for flashlights, headlamps, fans, and solar lights that see daily use.

• Genuine 2500mAh High Capacity (9.25Wh per cell)
  25% more energy than a standard 2000mAh battery. Gives you approximately 2.5 hours of bright light (300 lumens) or 6–8 hours of fan cooling per charge.

• Unprotected Design for Maximum Flexibility
  Shorter length fits tight battery compartments. Lower internal resistance ensures efficient power delivery with minimal heat. Must be used in devices with low‑voltage cutoff and charged with a 4.2V Li‑ion charger.

• Choose Button Top or Flat Top
  Button Top for secure spring‑contact connection. Flat Top for recessed contacts, welded packs, and devices that cannot accommodate extra length. Select the version your device manual specifies.

• Stable NMC Chemistry
  Maintains a flat 3.7V discharge curve from 4.2V down to 2.5V. Constant brightness, constant fan speed, consistent solar light output.

• Low Internal Resistance (≤75mΩ)
  Minimal voltage sag under load — even at 5A, the drop is only 0.375V. On typical 1–3A draws, it’s barely noticeable.

• 500+ Cycle Life & Low Self‑Discharge
  Recharge each cell over 500 times with minimal capacity loss. Store the spare for months at 3.6–3.7V; it will wake up with most of its charge intact.

• Built‑In Passive Safety
  PTC thermistor and resealable pressure vent provide foundational protection against over‑current and internal pressure. Nickel‑plated steel can resists drops and corrosion.

Technical Parameters

Applications

1. Flashlights & EDC Torches
Pop one of these 2500mAh cells into your favorite 18650 flashlight — whether it’s a pocket EDC light, a tactical torch, or a compact thrower — and enjoy hours of dependable illumination. Flat top for ultra‑tight battery tubes, button top for spring‑loaded hosts. Keep the second cell charged in your bag for instant swaps.

2. Headlamps for Work & Recreation
Trail runners, campers, mechanics, and DIYers will love the extended runtime. A headlamp on a comfortable 100‑lumen setting can run for over 7 hours on a single cell. The moderate weight keeps the headlamp balanced during active use.

3. Mini Fans & Portable Cooling
USB‑powered desk fans, handheld fans, and stroller fans all thrive on this 2500mAh battery. On low speed, one cell provides 6–8 hours of gentle airflow — enough for a full work shift or a night in a stuffy tent. The flat top fits recessed fan battery bays; the button top works in standard spring‑contact holders.

4. Solar‑Powered Garden & Path Lights
Many outdoor solar lights use removable 18650 cells. This 2‑pack is the perfect upgrade: swap out the small 1200–1500mAh stock batteries for these 2500mAh cells, and your lights will store more energy during the day, shining brighter and longer into the night. Ensure your solar light has its own charge controller and over‑discharge protection.

5. Backup & Emergency Power
Keep one cell in your device and one fully charged in a protective case. When the power goes out or your flashlight dims mid‑hike, you’ll have a spare ready to go. Low self‑discharge means the backup stays full for months.

6. DIY Electronics & STEM Projects
The flat top version is ready for spot welding into 2S or 3S battery packs for portable Bluetooth speakers, IoT sensors, or Arduino robots. The unprotected design gives you full control over your battery management system.

FAQ

Q1: Is this battery protected? Why not?
A: No, it’s an unprotected cell. We omit the protection PCB to keep the length as short as possible (fits more devices) and to reduce internal resistance. It’s safe when you use it in a device that already has its own low‑voltage cutoff (like most modern flashlights, headlamps, USB fans, and solar light controllers) and charge it with a proper 4.2V Li‑ion charger. The cell itself includes a PTC thermistor and a pressure vent for passive safety.

Q2: How do I choose between Button Top and Flat Top?
A: Check your device. If the positive contact is a spring with a physical ring around it, a Button Top is usually required to make firm contact. If the battery compartment is extremely tight or has a flat metal or PCB contact, you need a Flat Top. For building welded battery packs, always choose flat top.

Q3: Can I use this in a doorbell or remote control?
A: Remotes typically use AAA or AA batteries and cannot physically fit an 18650. Some wireless doorbells do take 18650s, but they sip power — a 2500mAh cell will last over a year, so the extra capacity is more than enough. This battery is best used in devices that actively draw current, like flashlights, fans, and headlamps.

Q4: How long will a 2500mAh battery run my mini fan?
A: On low speed (about 0.3–0.5A draw), expect 6–8 hours. On high speed (1–2A), around 1.5–2.5 hours. With two cells in the pack, you can swap and keep the breeze going all day.

Q5: Can I use these batteries in my solar lights?
A: Yes, if your solar light uses a removable 18650 and has its own charge controller with over‑discharge protection. Replacing the original 1500mAh cell with a 2500mAh will usually give you longer illumination at night. Always check the light’s battery compartment size — some are designed only for shorter or protected cells.

Q6: How should I store the spare battery?
A: Keep it in a plastic battery case, away from metal objects and moisture. For storage longer than a month, charge or discharge to about 3.6–3.7V (roughly 50% charge). Check the voltage every 3 months and recharge if it falls below 3.0V. Never store a completely empty battery.

Q7: How many times can I recharge these batteries?
A: Over 500 full charge/discharge cycles while still retaining at least 70% of the original capacity. With typical use, that’s years of reliable service.

Q8: Can I bring these on a plane?
A: Yes. At 9.25Wh per cell, they are well under the 100Wh IATA limit. Always carry lithium batteries in your hand luggage with the terminals insulated (tape or a plastic case).

Q9: Do I need a special charger?
A: Yes, you must use a charger designed for 3.7V Li‑ion batteries that terminates at exactly 4.2V. A quality charger will ensure safety and maximize the lifespan of your cells. Never use a NiMH or generic charger.