Hot Selling 18650 Battery Pack
11.1 V 2500mAh 18650 Battery Pack 18650-3S
- 16 Years Experience
- 200+ Certifications
- 1000+ Customers
- 7X24 Customer Support
-
Product Details
-
Specs
-
Content
-
FAQs
Reliable 2500mAh Battery for Longer Use
A true 2500mAh battery capacity gives your devices more time in the field—less charging, more fun and convenience.
Test Curves of 3.7v Battery
Take a closer look at the battery test curves—see the stability and performance you can trust for all your power needs!
- Cycle Life
- Self-Discharge
- Discharge Rate
- Temp Performance
Long-Lasting Power
This battery is a long-lasting powerhouse, retaining over 95% of its initial capacity even after 600 charge-discharge cycles. This outstanding longevity ensures a reliable and consistent performance, making it the perfect choice for devices that require extended use and durability.
Incredible Charge Retention
With an incredibly low self-discharge rate, this battery holds its charge exceptionally well. After a full year of storage, its voltage only shows a minimal drop from 4.15V to 4.05V, keeping your device ready to go even after long periods of inactivity.
Learn More About Discharge Rate 
Discharge Characteristics
Experience stable and reliable power delivery. The battery maintains an operating voltage above 3.4V for over 80% of its discharge cycle, ensuring consistent performance. It also delivers high capacity, retaining over 90% even at a high 5.0C discharge rate.
Extreme Temperature Performance
This battery is built for a wide range of climates. It offers consistent, high-capacity performance from 25°C to 60°C. Even in freezing conditions, it remains reliable, providing approximately 65% of its capacity at a frigid -30°C.
Power Up Anywhere with Our 11.1V 18650 Pack
Your trust matters to us. That's why Ufine Battery uses only the finest materials and cutting-edge processes to ensure unbeatable quality.
View More 11.1 V Lithium Battery Pack 
Plug-and-Play with Brand Connector
Ready-to-Use Connector for Quick Installation
Equipped with Molex connector and UL1007 22AWG wires, it’s ready to connect, install, and go—no complicated setup needed.
- UL1007 certified 22AWG wire supports stable current delivery and long-term durability
- Consistent wire color coding helps users avoid misconnection and speeds up assembly
- Ideal for consumer product integration—no soldering or wiring modifications required
- Perfect for prototyping and mass production with plug-and-play simplicity
Why Choose Ufine Battery
Ufine Battery (Direct Factory)
- Direct manufacturer with full production control, ensuring consistent quality for every 18650 battery pack
- Volume-based pricing with competitive factory cost
- Supports custom 3.7V battery pack size, PCM/BMS, connectors, cables, and configurations
- Flexible MOQ, suitable for prototypes and small pilot runs
- 17 years of lithium battery manufacturing experience; provides technical drawings, pack design, and engineering guidance
- Complete reports available: MSDS, UN38.3, CE, RoHS, etc.
- Stable production with predictable lead time, ideal for OEM/ODM projects
- Professional after-sales service with quick response for B2B clients
Ordinary Channels / Traders / Small Workshops
- Often resell from unknown factories; inconsistent quality and higher failure risk
- Middleman markups lead to unstable or higher pricing
- Limited or no customization; mostly standard products only
- High MOQ, difficult for new projects to start
- Little to no technical support; only sells finished goods
- Certifications often missing or incomplete, causing delays in shipping or customs
- Lead time uncertain; stock availability unstable
- Limited support; difficult to handle quality claims
Battery Specification
-
1. Mechanical Characteristics
Cell 18650-3S PCM Yes NTC Yes Weight appr. 145g Configuration 3S1P -
2. Electrical Specification
Capacity 2500mAh Nominal Voltage 11.1V Energy 27.75Wh Internal Resistance less than 170mΩ Max. Charge Voltage 12.6V Discharge Cut Off 8.25V Max. Charge Current 2500mA Max. Discharge Current 2500mA Standard Charge Current 500mA Standard Discharge Current 500mA Charging Temperature 0℃ to 45℃ Discharging Temperature -20℃ to 60℃ Storage Temp.Range 1 year at -20℃ to +30℃ 3 mos. at -20℃ to +45℃ 1 mo. at -20℃ to +60℃ Cycle life 100 cycles ≥92% 300 cycles ≥88% 500 cycles ≥80% -
3. Cell protection
Overcharge Detection 4.28V ±50mV (80 to 200msec delay, release 4.08V ±50mV) Overdischarge Detection 2.9V ±100mV (40 to 120msec. delay, release 3.0V ±100mV) Overcurrent Detection 5A to 9A (9 to 15msec. delay) Short protection Yes
Part 1. What does “3S” mean in a battery?
“3S” refers to three lithium-ion cells connected in series:
-
Voltage is additive, capacity stays the same
-
Each 18650 2500mAh cell has a nominal voltage of 3.7V
-
Three cells in series produce 11.1V nominal
This configuration is ideal for devices requiring more power without increasing parallel cells.
Understanding S and P in Lithium Battery Packs
Part 2. Energy of a 18650-3S 2500mAh 11.1V battery pack
Battery energy (Wh) = Voltage × Capacity (Ah)
For this pack: 11.1V × 2.5Ah = 27.75Wh
The pack can theoretically deliver 27.75 watts for 1 hour or 13.88 watts for 2 hours, depending on device consumption.
Part 3. Types of cells in a 3S battery pack
3S li-ion packs typically use high-quality 18650 cells. Common chemistries:
| Cell Type | Energy Density | Safety | Typical Use |
|---|---|---|---|
| NCM/NMC | High | Medium | Consumer electronics |
| LCO | Very High | Medium | Cameras, high-end gadgets |
| LFP | Medium | Very High | Power tools, e-bikes |
Most 18650 3S 2500mAh packs use NCM/NMC cells, balancing energy density, safety, and cost.
Want to convert battery Wh to Watts? Use our online calculator↓↓↓Part 4. How long can a 18650-3S 2500mAh battery last?
Runtime (hours) = Energy (Wh) ÷ Device Power (W)
Example: Device consuming 8W → 27.75 ÷ 8 ≈ 3.47 hours
-
Flashlights: 2–8 hours
-
Smart toys: 3–6 hours
-
Bike alarms: 7–14 days (intermittent)
-
Handheld instruments: 3–10 hours
-
Smart home devices: 12–72 hours
Part 5. Can you DIY a 3S 18650 battery pack?
DIY is possible but requires caution:
-
Match cell voltages correctly
-
Use proper connection techniques (spot welding recommended)
-
Install BMS for protection
-
Ensure proper insulation and casing
⚠️ Mistakes can cause overheating, swelling, or fire. Pre-assembled packs are safer for most users.
How to Connect Lithium Batteries in Series and Parallel?Part 6. Choosing connectors and wires
Stable power and safety depend on proper wiring:
-
Use UL1007 22AWG wires or thicker
-
Reliable connectors like Molex
-
Maintain correct polarity and color coding
-
Short and secure cable routes for portable devices
Part 7. Selecting a charger for a 3S 18650 battery pack
Key points:
-
Charging voltage: 12.6V (4.2V × 3 cells)
-
CC/CV mode recommended
-
Charge current: 0.2C–1C (0.5–2.5A for 2500mAh)
-
Use chargers with safety protections and indicators
❌ Avoid incompatible or generic chargers.
Part 8. Common mistakes to avoid
⚠️ Mixing old and new cells
⚠️ Bypassing the BMS
⚠️ Using incorrect chargers
⚠️ Improper wires or connectors
⚠️ Operating outside temperature limits
Part 9. Conclusion
A 3S 18650 2500mAh 11.1V battery pack is versatile, safe, and reliable for consumer electronics, DIY projects, and portable devices. Its compact size, long runtime, and plug-and-play design make it ideal for global applications. Prioritizing quality cells, proper wiring, and certified chargers ensures maximum efficiency and safety.
FAQs
-
What is the typical cycle life of a 3S 18650 battery pack?
Most packs last around 300 full charge/discharge cycles under proper conditions. -
Can I use a 3S battery pack for 12V devices?
Yes. An 11.1V lithium-ion battery is compatible with most “12V” electronics, which can tolerate voltage variations. -
How is a 3S li-ion battery different from a single 18650 cell?
Series connection increases voltage (11.1V vs 3.7V), while capacity remains the same. -
Does temperature affect performance?
Yes. High temperatures shorten lifespan, and output may decrease below 0°C. This pack can operate between –20°C and 60°C. -
How can I estimate the 2500mAh battery price?
Prices vary by manufacturer, quality, and certification. Generally, 2500mAh 3S lithium-ion packs cost slightly more than lower-capacity 18650 3S battery packs due to energy density and protective circuitry. -
Can I transport a 3S 18650 battery pack internationally?
Yes, if the pack meets UN38.3 and MSDS standards, it can be shipped globally.
Ready to Power Your Project?
We’ll help you design the perfect power source — tailored to your voltage, capacity, size, C-rate, and performance needs.
Contact Us NowWhat Our Customers Are Saying
We love hearing from you! Your experiences help us improve and inspire others. Check out what our happy customers have to say about our lithium batteries—share your thoughts with us too!
Latest Articles
About Lithium Battery Industry News
Graphene Battery vs Lithium Battery: Which is Better?
Compare graphene battery vs lithium battery in energy density, charging speed, lifespan, cost, and EV applications. Learn which battery leads in 2025.
2025-11-24 Ufine
What is the Difference Between MCA and CCA on Batteries?
Learn the difference between MCA and CCA batteries. Understand what MCA means, what CCA is, and how to choose the right battery for vehicles or marine engines.
2025-11-24 Ufine
Type of Lithium Battery Voltage
Learn lithium ion battery voltage, nominal voltage, and voltage range. Compare Li-ion, LiPo, LiFePO4, and 18650 voltages, charging, and device compatibility.
2025-11-24 Ufine
