Samsung 25R 2500mAh 20A Button Top Battery 2-Pack with Nitecore UM2 Smart Charger – High-Drain Power Kit for Flashlights, and Cordless Tools

What’s in This Bundle:

• 2x Samsung 25R 2500mAh 20A Button Top Batteries – Factory-fresh, high-drain 18650 cells.

• 1x Nitecore UM2 Intelligent Dual-Slot Charger – Smart charging with LCD display and QC 2.0 fast input.

• 1x USB-C Charging Cable – Ready to plug into wall adapters, power banks, or laptops.
  (Note: This kit does not include an AC wall adapter.)

Product Description:

Most 18650 batteries can't handle serious punishment. The Samsung 25R is the exception. For years, it's been the go-to choice for enthusiasts and tradespeople who refuse to compromise on power delivery. It delivers a rock-solid 20A continuous discharge, which means your high-wattage  tactical flashlight, or cordless tool gets consistent current without performance drops.

This kit pairs two factory-fresh 25R button-top cells with the Nitecore UM2 charger. The UM2 is more than a simple power brick. It uses a smart chip to automatically detect battery chemistry, then applies the ideal charging profile. The bright LCD screen gives you real-time readings on voltage, current, and capacity, so you know exactly what's happening.

It supports QC 2.0 fast input, pushing up to 1500mA into each slot. That means a 3500mAh battery hits 80% charge in just over two hours. There's also an IMR-optimized program that keeps high-current cells running at their peak, plus an over-discharge repair function that can revive batteries you'd otherwise toss.

You get a power solution that actually works, day after day.

Key Benefits:

• 20A continuous output – Real, sustained power for demanding electronics.

• Up to 35A pulse burst – Handles short-duration power spikes without breaking a sweat.

• Fast QC 2.0 charging – 1500mA per slot means less waiting.

• Smart battery detection – The UM2 reads your battery and picks the right charge curve automatically.

• LCD status screen – Check voltage, current, and capacity in real time.

• Repair mode included – Revives over-discharged or deeply drained cells.

• Full safety suite – Reverse polarity, short-circuit, and heat protection all built-in.

Technical Specifications:

Battery - Samsung 25R (Button Top):

• Brand: Samsung SDI

• Model: INR18650-25R

• Capacity: 2500mAh

• Voltage: 3.6V / 3.7V

• Continuous Discharge: 20A

• Pulse Discharge: Up to 35A (short bursts only)

• Standard Discharge: 10A (for longer cycle life)

• Internal Resistance: ≤18mΩ

• Chemistry: Li-ion NMC

• Cut-Off Voltage: 2.5V

• Operating Temp (Discharge): -20°C to 75°C

• Cycle Life: 250+ cycles at 20A

• Weight: 45g

Charger - Nitecore UM2:

• Input: DC 5V/2A, 9V/2A (QC 2.0)

• Max Output: 1500mA per slot

• Total Output: 3000mA

• Display: LCD (voltage, current, capacity)

• Protection: Reverse polarity, short-circuit, overheat, over-charge

Complete Battery Compatibility List:

• Dimensions: 152mm × 73mm × 40mm

• Weight: 148.3g

Applications:

• High-wattage and rebuildable atomizers

• High-lumen tactical flashlights and searchlights

• Cordless drills, impact drivers, and rotary tools

• High-torque RC cars and drones

• Portable power stations and battery banks

Frequently Asked Questions (FAQ):

Q1: What's the real-world difference between 20A continuous and 35A pulse?
A: The 20A rating is the safe, long-term current you can pull without damaging the cell. The 35A rating is what the battery can deliver in short, milliseconds-long bursts—like pressing a high-wattage fire button or starting a motor. You shouldn't run it at 35A continuously; that would overheat the cell and shorten its life. Treat it as a 20A battery and you'll be fine.

Q2: Can I use the UM2 charger with LiFePO4 batteries?
A: Yes. The UM2 automatically detects LiFePO4 cells and switches to the correct 3.2V charge profile. No manual setup is required.

Q3: What should I do if the charger shows "EE EE" on the screen?
A: That's the charger's way of saying it found a battery that's been over-discharged or is possibly damaged. The UM2 has a built-in repair mode—just press and hold the "V" button to try to revive a deeply drained cell.

Q4: Can I charge different battery sizes at the same time?
A: Absolutely. The UM2 has two independent slots, so you can charge an 18650 in one slot and a 21700 in the other without any issues. Check the compatibility list above to ensure both sizes are supported.

Q5: Can I power the UM2 from a power bank or solar panel?
A: Yes. The USB-C input makes it compatible with wall adapters, power banks, car chargers, and even portable solar panels—ideal for field use or road trips.