Why This Bundle
The Molicel P28A takes the acclaimed P26A formula and pushes the capacity a bit further — 2800mAh at the same 35A continuous discharge rating, with the same low internal resistance and flat voltage curve under load. A set this capable deserves a charger that can handle every cell at once while keeping close watch on their health. This bundle pairs 4 genuine Molicel INR18650-P28A Flat Top batteries with the NITECORE UMS4, a QC-enabled 4-slot charger with a detailed LCD display, independent bay control, and multiple layers of protection — ready to use straight out of the box.
Molicel INR18650-P28A (Flat Top) Specifications
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| Item |
Spec |
| Model |
Molicel INR18650-P28A (Flat Top) |
| Typical Capacity |
2800mAh |
| Minimum Capacity |
2600mAh |
| Nominal Voltage |
3.6V |
| Max Continuous Discharge |
35A (rated with 80°C thermal cutoff) |
| Standard Charge Current |
2.8A |
| Maximum Charge Current |
6A |
| Charge Cutoff Voltage |
4.20±0.05V |
| Discharge Cutoff Voltage |
2.5V |
| Internal Resistance |
≤20mΩ (AC 1kHz) |
| Chemistry |
INR (Lithium Nickel Manganese), high-drain |
| Cell Size |
18650 (approx. |
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Φ18.5mm × 65.15mm) |
Terminal Type |
Flat Top — level positive terminal, suited for devices requiring full-surface contact |
Typical Use |
Power tools, high-output flashlights, electric mobility, battery pack builds, and other demanding high-drain applications |
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Note: This is a high-drain, unprotected 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 UMS4
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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 adapter
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QC Mode output: 3,000mA×1 / 2,000mA×2 / 1,000mA×4 — Standard Mode: 2,000mA×1 / 1,000mA×2 / 500mA×4
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Independent 4-bay control: charge and monitor up to 4 batteries separately, with each bay unaffected by the others
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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 voltage and current for specialized battery types
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Safety features: automatic internal resistance detection, reverse-polarity and short-circuit protection, overtime charging protection, and over-discharged battery activation/restoration
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Fire-retardant PC/ABS housing with built-in temperature regulation
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Universal power input: works with wall adapters, power banks, and solar panels via USB-C
NITECORE UMS4 – Supported Battery Types & Voltage
Compatible with 3.6V/3.7V Li-ion, 3.8V Li-ion, 3.2V LiFePO4, and 1.2V Ni-MH/Ni-Cd batteries, including the Molicel P28A (18650) in this bundle:
IMR/Li-ion/LiFePO4: 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 Ni-MH/Ni-Cd: AA, AAA, AAAA, C, D
Output current: up to 3,000mA per bay (QC mode) / 4,000mA total
Compatibility Notes
The UMS4 uses spring-loaded contacts that accommodate Flat Top batteries securely without any adapter. P28A Flat Top cells measure about 65.15mm, well within the UMS4's compatible battery range. All 4 cells in this bundle can be charged simultaneously across the charger's 4 independent bays.
Note: When only 1 bay is in use, the UMS4 can reach up to 3,000mA with a QC adapter — close to the P28A's 2.8A standard charge current. With all 4 bays in use, each will charge more gently at up to 1,000mA (QC mode) or 500mA (standard mode).
What's Included
- Molicel INR18650-P28A Flat Top Battery × 4
- NITECORE UMS4 4-Bay Charger × 1
- USB-C Charging Cable × 1
- User Manual × 1
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 UMS4
- The P28A is an unprotected, high-drain cell intended strictly for compatible, purpose-built devices — do not use it in unauthorized or modified equipment
- Never discharge below 2.5V or charge above 4.2V
- 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 UMS4 charge Molicel P28A Flat Top batteries safely? A: Yes. The UMS4 automatically detects Li-ion chemistry and applies the correct charging voltage (4.2V) and current for P28A cells, with real-time monitoring on its LCD display.
Q: Can I charge all 4 batteries at the same time? A: Yes. The UMS4 has 4 independent bays and can charge all 4 cells simultaneously — up to 1,000mA per bay in QC mode, or 500mA per bay in standard mode, when all 4 slots are used at once.
Q: Will Flat Top batteries sit properly in the UMS4 charger bays? A: Yes. The UMS4's spring-loaded contacts are designed to accommodate both Flat Top and Button Top cells without any adapter or modification.
Q: How do I know if a P28A battery is degraded? A: The UMS4'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 35A continuous discharge safe for everyday devices? A: No — the P28A is a high-drain cell intended strictly for devices specifically engineered for high continuous discharge, such as certain power tools, and high-output flashlights. Always check your device's battery requirements before use.
Q: Can I power the UMS4 with a power bank while traveling? A: Yes. The UMS4 has a USB-C input and works with wall adapters, power banks, and solar panels.
Q: How does the P28A compare to the P26A? A: Both share the same 35A discharge rating and low internal resistance, performing almost identically under heavy load. The P28A offers a bit more capacity (2800mAh vs. 2600mAh), giving slightly longer runtime in lower-power situations.
Q: What's in the box? A: 4 Molicel INR18650-P28A Flat Top batteries, 1 NITECORE UMS4 charger, a USB-C charging cable, and a user manual.
