Why This Bundle
High-drain batteries perform best with a charger built to match their charging profile. This bundle pairs genuine Samsung 25R Button Top cells with the NITECORE UI2 — a compact, USB-C powered charger that automatically selects the right charging mode and includes trickle charging and over-discharge protection. Everything you need to charge and maintain your cells, ready out of the box.
This listing is for Button Top. Looking for Flat Top? Click here to buy: Samsung INR18650-25R Flat Top + NITECORE UI2 Bundle.
Samsung INR18650-25R (Button Top) Specifications
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| Item |
Spec |
| Model |
Samsung INR18650-25R (Button Top) |
| Rated Capacity |
2500mAh |
| Nominal Voltage |
3.6V |
| Max Continuous Discharge |
20A |
| Charge Cutoff Voltage |
4.2V |
| Chemistry |
NMC (Lithium Nickel Manganese Cobalt Oxide) |
| Cell Size |
18650 (approx. |
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Φ18.4mm × 65.3mm) |
Terminal Type |
Button Top — positive terminal has a raised nub, suited for devices requiring point contact |
Typical Use |
High-output flashlights, power tools, DIY battery packs, and other high-drain applications |
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Note: High-drain cells demand careful handling — avoid mixing with batteries of a different brand, model, or charge state, and inspect the wrap for damage before every use to prevent short circuits.
The Charger: NITECORE UI2
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USB-C input: charge from any 5V power bank, solar panel, or USB adapter — great for travel and outdoor use
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Automatic CC/CV Charging: intelligently selects the most suitable charging mode for each cell
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Independent Dual-Bay Control: each of the 2 bays charges independently without affecting the other
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Trickle Charging: automatically switches to 100mA trickle mode for batteries below 2.9V, then up to 1000mA standard charging above 2.9V
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Over-Discharge Activation: automatically detects and reactivates over-discharged protected Li-ion cells
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Multiple Safety Protections: reverse-polarity/short-circuit protection, intelligent temperature control, and overcharge protection
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Ultra-Compact & Lightweight: just 79.5g, 125.5 × 59.5 × 32.1mm
NITECORE UI2 – Supported Battery Types & Voltage
Charges 3.6V/3.7V Li-ion/IMR batteries, including the Samsung 25R (18650) in this bundle:
10340, 10350, 10440, 10500, 12340, 12500, 12650, 13450, 13500, 13650, 14430, 14500, 14650, 16500, 16340 (RCR123), 16650, 17350, 17500, 17650, 17670, 18350, 18490, 18500, 18650, 20700, 21700, 22500, 22650, 25500, 26500, 26650
Output voltage: 4.2V±1% Output current: up to 1000mA per bay (max 2 bays simultaneously)
Compatibility Notes
The UI2's charging bays are open-ended, allowing both Button Top and Flat Top batteries to seat properly without any adapter. Samsung 25R Button Top cells measure about 65.3mm, well within the UI2's compatible battery range.
What's Included
- Samsung INR18650-25R Button Top Battery × 2
- NITECORE UI2 Charger × 1
- USB-C Charging Cable × 1
- User Manual × 1
This listing is for Button Top. For Flat Top click here
Safety Tips
- Store batteries in a proper case, keeping them away from loose metal objects to prevent short circuits
- Never disassemble, puncture, burn, or submerge the batteries
- Charge only with a genuine, compatible charger such as the NITECORE UI2
- These are high-drain cells intended for compatible, purpose-built devices — do not use them in unauthorized or modified equipment
FAQ
Q: Can the NITECORE UI2 charge Samsung 25R Button Top batteries safely? A: Yes. The UI2 automatically selects the optimal CC/CV charging mode for Li-ion cells like the 25R, with a 4.2V±1% output voltage and up to 1000mA per bay.
Q: What's the difference between Button Top and Flat Top batteries? A: The only difference is the shape of the positive terminal — Button Top has a raised nub for point contact, while Flat Top is level. Capacity, voltage, and discharge rate are identical.
Q: Do I need an adapter to charge Button Top batteries in the UI2? A: No. The UI2's open charging bays accommodate both Button Top and Flat Top cells without any adapter.
Q: Can I charge both batteries at the same time? A: Yes. The UI2 has 2 independent bays, each capable of up to 1000mA, and one battery's charging status does not affect the other.
Q: Can I power the UI2 with a power bank while traveling? A: Yes. The UI2 has a USB-C input and works with any 5V power source, including power banks, solar panels, and USB wall adapters.
Q: What happens if a battery has over-discharged? A: The UI2 includes an over-discharge activation feature that automatically detects and reactivates protected Li-ion cells that have dropped too low from storage or improper use.
Q: Is 20A continuous discharge safe for everyday devices? A: These are high-drain cells built for devices that specifically call for high continuous discharge, such as certain flashlights, and power tools. Always check your device's battery requirements before use.
Q: What's in the box? A: 2 Samsung INR18650-25R Button Top batteries, 1 NITECORE UI2 charger, a USB-C charging cable, and a user manual.
