Why This Bundle
The Samsung 20S is one of the hardest-hitting 18650 cells available — built for devices that demand serious continuous current. A cell this powerful deserves a charger that can monitor it closely and charge it safely. This bundle pairs 2 genuine Samsung 20S Flat Top batteries with the NITECORE UMS2, a QC-enabled dual-slot charger with a detailed LCD display, independent bay control, and multiple layers of protection — ready to use straight out of the box.
This listing is for Flat Top. Looking for Button Top? Click here to buy: Samsung INR18650-20S Button Top + Nitecore UMS2 Bundle.
Samsung INR18650-20S (Flat Top) Specifications
| Item |
Spec |
| Model |
Samsung INR18650-20S (Flat Top) |
| Rated Capacity |
2000mAh (min.) |
| Nominal Voltage |
3.6V |
| Max Continuous Discharge |
30A |
| Charge Cutoff Voltage |
4.20V |
| Discharge Cutoff Voltage |
2.5V |
| Chemistry |
IMR (Lithium Manganese, high-drain) |
| Cell Size |
18650 (approx. Φ18.43mm × 65.0mm) |
| Terminal Type |
Flat Top — level positive terminal, suited for devices requiring full-surface contact |
| Typical Use |
Battery pack assemblies, power tools, high-output flashlights, electric mobility systems, and other extreme high-current applications |
Note: This is an extremely high-drain cell — 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 UMS2
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USB-C input with QC support: up to 4,000mA total output; up to 3,000mA on a single bay with a QC 2.0+ adapter, or 1,000mA per bay (2,000mA total) with a standard 5V/2A source
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Independent dual-bay control: charge and monitor 2 batteries separately, without one affecting the other
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Detailed real-time LCD display: shows battery health (Good/Poor), internal resistance, charging current, voltage, battery type, charged capacity, charging time, cut-off voltage, and charging mode
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3 automatic charging modes: CC, CV, and -dV/dt, selected automatically based on battery type and charge level
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Manual adjustment: set charging current and cut-off voltage for specialized battery types
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Safety features: automatic internal resistance detection, reverse-polarity and short-circuit protection, over-discharged battery activation/restoration, and automatic termination on full charge
- Fire-retardant PC/ABS housing
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Universal power input: works with wall adapters, power banks, car chargers, and solar panels via USB-C
NITECORE UMS2 – Supported Battery Types & Voltage
Compatible with 3.6V/3.7V Li-ion/IMR/LiFePO4 batteries, including the Samsung 20S (18650) in this bundle:
10440, 14500, 14650, 16500, 16340 (RCR123), 16650, 17350, 17500, 17650, 17670, 17700, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22500, 22650, 25500, 26500, 26650, 26700
Also compatible with 1.2V Ni-MH/Ni-Cd batteries: AA, AAA, AAAA, C, D
Output current: QC Mode — 3,000mA×1 / 2,000mA×2 · Standard Mode — 2,000mA×1 / 1,000mA×2
Compatibility Notes
The UMS2 uses spring-loaded contacts that accommodate Flat Top batteries securely without any adapter. Samsung 20S Flat Top cells measure about 65.0mm, well within the UMS2's compatible battery range.
What's Included
- Samsung INR18650-20S Flat Top Battery × 2
- NITECORE UMS2 Charger × 1
- USB-C Charging Cable × 1
- User Manual × 1
This listing is for Flat Top. For Button 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 UMS2
- The Samsung 20S is an extreme high-drain cell intended strictly for compatible, purpose-built devices designed for 30A continuous discharge — do not use in unauthorized or modified equipment
- Flat Top batteries are commonly used in devices with spring or flat-contact battery holders (e.g., battery packs and power tools) — check your device's terminal requirements before use
FAQ
Q: Can the NITECORE UMS2 charge Samsung 20S Flat Top batteries safely? A: Yes. The UMS2 automatically detects Li-ion/IMR chemistry and applies the correct charging voltage (4.2V) and current for 20S cells, with real-time monitoring on its LCD display.
Q: What's the difference between Flat Top and Button Top batteries? A: The only difference is the shape of the positive terminal — Flat Top is level for full-surface contact, while Button Top has a raised nub. Capacity, voltage, and discharge rate are identical.
Q: Will Flat Top batteries sit properly in the UMS2 charger bays? A: Yes. The UMS2's spring-loaded contacts are designed to accommodate both Flat Top and Button Top cells without any adapter or modification.
Q: Can I charge both batteries at the same time? A: Yes. The UMS2 has 2 independent bays. With a QC adapter you'll get up to 2,000mA per bay simultaneously (or 3,000mA if only one bay is in use); with a standard 5V/2A source, up to 1,000mA per bay.
Q: How do I know if a 20S battery is degraded? A: The UMS2's LCD display shows battery health as "Good" or "Poor" along with internal resistance readings, making it easy to spot cells that have aged or lost performance.
Q: Is 30A continuous discharge safe for everyday devices? A: No — the Samsung 20S is one of the highest-drain 18650 cells available and is intended strictly for devices specifically engineered for extreme continuous discharge, such as certain power tools, high-output flashlights, and professional battery pack assemblies. Always confirm your device's current requirements before use.
Q: Can I power the UMS2 with a power bank while traveling? A: Yes. The UMS2 has a USB-C input and works with wall adapters, power banks, car chargers, and solar panels.
Q: What's in the box? A: 2 Samsung INR18650-20S Flat Top batteries, 1 NITECORE UMS2 charger, a USB-C charging cable, and a user manual.
