Molicel INR21700-P42A 4200mAh 45A 21700 Battery 4-Pack with Nitecore UMS4 Smart Charger – Extreme High-Power Kit for Professional Camera Flashes, Performance Drones & High-End Setups

Why This Bundle

The Molicel P42A is one of the strongest 21700 cells available — a 4200mAh typical capacity paired with a genuine 45A continuous discharge rating and a very low AC impedance (<15mΩ), making it a favorite for high-drain battery pack builds that need serious current without sacrificing runtime. 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 INR21700-P42A 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 INR21700-P42A Specifications

Important: Molicel positions the P42A as a pack-only, high-power cell intended for use within a properly engineered battery management system (BMS) — not as a standalone consumer replacement cell for casual devices.

This is an 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

• USB-C input with QC support: up to 4,000mA total output; up to 3,000mA on a single bay with a QC adapter — still well below the P42A's 4.2A standard charge current, but a meaningful step up from a basic dual-slot charger
• QC Mode output: 3,000mA×1 / 2,000mA×2 / 1,000mA×4 — Standard Mode: 2,000mA×1 / 1,000mA×2 / 500mA×4
• Independent 4-bay control: charge and monitor up to 4 batteries separately, with each bay unaffected by the others
• 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
• 3 automatic charging modes: CC, CV, and -dV/dt, selected automatically based on battery type and charge level
• Manual adjustment: set charging voltage and current for specialized battery types
• Safety features: automatic internal resistance detection, reverse-polarity and short-circuit protection, overtime charging protection, and over-discharged battery activation/restoration
• Fire-retardant PC/ABS housing with built-in temperature regulation
• 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 P42A (21700) 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 and its bays are sized to comfortably fit 21700 cells like the P42A. Compared to a basic dual-slot travel charger, the UMS4's higher per-bay output (up to 3,000mA with a QC adapter on a single bay) narrows the gap to the P42A's 4.2A rated charge current considerably, though it still won't reach the cell's full rated charge speed.

Note: With all 4 bays occupied, each will charge more gently at up to 1,000mA (QC mode) or 500mA (standard mode) — a safe charging pace for four high-power cells at once, though full charges will still take a few hours given the current gap versus the P42A's rated 4.2A.

What's Included

• Molicel INR21700-P42A 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 P42A is an unprotected, ultra-high-power cell intended for use within a properly engineered battery pack with its own BMS — do not use it as a standalone replacement cell in casual consumer devices
• Never discharge below 2.5V or charge above 4.2V

FAQ

Q: Can the NITECORE UMS4 charge Molicel P42A batteries safely? A: Yes. The UMS4 automatically detects Li-ion chemistry and applies the correct charging voltage (4.2V) and current for P42A cells, with real-time monitoring on its LCD display. Its per-bay output is still below the P42A's full 4.2A rated charge current, but it charges these cells considerably faster than a basic low-current charger.

Q: Is the P42A meant for use in standalone devices like flashlights? A: Molicel positions the P42A as a pack-only cell intended for use within a properly designed battery management system, not as a standalone drop-in cell for casual consumer devices. It's built for power tools, EVs/PHEVs, and engineered high-drain battery packs.

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 21700 batteries fit properly in the UMS4? A: Yes. The UMS4's bays and spring-loaded contacts are sized to accommodate 21700 cells like the P42A without any adapter.

Q: How do I know if a P42A 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: 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: What's in the box? A: 4 Molicel INR21700-P42A batteries, 1 NITECORE UMS4 charger, a USB-C charging cable, and a user manual.