Molicel INR-21700-P42A 4200mAh 3.7V Flat Top Battery (2-Pack) – 45A High Drain for Turbo Flashlights, RC Models & Power Tools

Lithium-ion/NMC 21700The Legendary Molicel P42A: Where Brutal Power Meets Endurance
The Molicel INR-21700-P42A isn’t just another 21700 cell — it’s the gold standard by which all other high‑drain batteries are judged. Beloved by flashlight hot‑rodders, FPV drone pilots, and power‑tool rebuilders, the P42A delivers a genuine 45A continuous discharge while still holding a substantial 4200mAh capacity. This 2‑pack puts that legendary performance in your hands, giving you the freedom to build, swap, and run your most demanding gear without compromise.

True 45A Continuous — No Marketing Gimmicks
Unlike cells that inflate their pulse ratings, the P42A is engineered to sustain a full 45 amps of continuous current. With an ultra‑low internal resistance of approximately ≤14mΩ, voltage sag is virtually nonexistent even under extreme loads. Your turbo flashlight will hold its retina‑searing brightness until thermal regulation kicks in, not electrical starvation. Your RC truggy will explode out of corners with relentless torque. Your cordless impact wrench will snap stubborn bolts loose without stalling. And because the cell can pulse even higher for short bursts, you’ll always have headroom for the split‑second surges that define high‑performance applications.

4200mAh Capacity — Runtime That Respects the Amps
High‑drain cells often force you to accept pitiful runtime in exchange for current. The P42A rewrites that rule. Its 4200mAh capacity stores approximately 15.5 watt‑hours of energy — significantly more than the 3000mAh typical of ultra‑high‑drain cells. In a turbo flashlight, you’ll enjoy extended sessions of full‑brightness output before reaching for the charger. In an RC car, you’ll complete full race heats with power to spare. In a rebuilt drill battery, you’ll drive dozens of screws on a single charge. This is the cell that finally lets you have both explosive power and meaningful endurance.

Flat‑Top and Unprotected — The Enthusiast’s Blueprint
Molicel supplies the P42A as an unprotected, flat‑top bare cell — exactly as the high‑performance community demands. The flush positive terminal measures 70.0mm from end to end, the universal standard for 21700‑compatible devices. It drops effortlessly into the tightest flashlight tubes (Noctigon, Emisar, Fireflies), mates perfectly with pogo‑pin contacts in drone battery sleds, and welds cleanly into power‑tool packs and custom DIY builds. Omitting the external protection PCB eliminates unwanted length and resistance, ensuring your devices receive every amp they demand. Naturally, this design requires you to use a quality charger with precise 4.2V termination and to install the cell only in devices that have built‑in low‑voltage cutoff — a feature found in every modern turbo flashlight, brushless RC ESC, and cordless‑tool motor controller. The cell itself incorporates a built‑in PTC thermistor, resealable safety vent, and CID for multi‑layered passive protection.

Two Cells, Zero Downtime
The 2‑pack configuration is the smart choice for anyone who relies on their gear. Build a 2S pack for higher‑voltage applications. Keep one cell in your device and one fully charged in your bag. Swap on the fly when the first cell runs dry, and keep your light shining, your drone flying, or your tool driving without interruption.

Built to Last, Even Under Extreme Stress
Molicel’s advanced INR (Nickel‑Manganese‑Cobalt) chemistry provides a flat 3.7V nominal discharge curve and exceptional thermal stability. The P42A is rated for over 500 full charge/discharge cycles while retaining at least 70% of its initial capacity. Its low self‑discharge rate allows you to store spare cells for months at the recommended 3.6–3.7V without significant power loss. The nickel‑plated steel can resist corrosion, impact, and the punishing vibrations of power tools, RC vehicles, and outdoor use. Built‑in safety features — PTC thermistor, resealable vent, and CID — give you confidence even under the most extreme loads.

Key Features

• 45A Continuous High Drain — The P42A Standard
  Genuine 45A sustained output handles the most demanding turbo flashlights, RC motors, and power tools without voltage sag. No inflated pulse ratings — just honest, relentless current.

• 4200mAh Genuine Capacity (15.5Wh per cell)
  Enjoy meaningful runtime alongside extreme discharge capability. Enough for extended turbo sessions, full RC heats, or dozens of tool operations per charge.

• Unprotected Flat‑Top Design
  Standard 70.0mm length and flush positive terminal fit all 21700‑compatible devices. Eliminates PCB resistance for maximum power delivery. Requires a quality 4.2V charger and device with low‑voltage cutoff.

• Ultra‑Low Internal Resistance (≤14mΩ)
  Voltage drop at 45A is minimal. Keeps your devices in regulation and your performance at its peak without generating excessive heat.

• Stable INR (NMC) Chemistry
  Maintains a flat 3.7V discharge curve. Light output, motor RPM, and tool torque stay predictable from full charge to cutoff.

• 500+ Cycle Life & Low Self‑Discharge
  Recharge hundreds of times with minimal capacity fade. Stores for months at 3.6–3.7V, always mission‑ready.

• Multi‑Layered Passive Safety
  Built‑in PTC thermistor, resealable safety vent, and CID protect against over‑current, over‑pressure, and short circuits.

• Rugged Nickel‑Plated Steel Can
  Corrosion‑resistant and impact‑resistant. Handles the harshest conditions of power tools, RC vehicles, and outdoor environments.

• 2‑Pack Value
  Two identical cells for building, swapping, or backing up. Keep your gear running without interruption.

Technical Parameters

Applications

1. Turbo Flashlights & High‑Lumen Hot‑Rods
For FET‑driven, multi‑emitter, or custom SBT90.2 flashlights that pull 20–45A on turbo, the P42A is the ultimate power source. It holds voltage rock‑steady for maximum brightness without early step‑down. The flat‑top design is essential for ultra‑tight enthusiast tubes.

2. RC Cars, Trucks, Boats & Racing Drones
Build a 2S or 3S Li‑ion pack for 1/10 and 1/8 scale vehicles, or a 4S/6S pack for high‑power drones. The 45A continuous output feeds brushless motors with explosive acceleration and sustained top speed. Flat‑top terminals allow clean, low‑profile spot welds.

3. Cordless Power Tools (Rebuilds & Upgrades)
Replace worn‑out cells in high‑torque drills, impact drivers, circular saws, and angle grinders. The P42A handles the 20–40A startup spikes of professional tools, while the 4200mAh capacity provides excellent runtime. Flat‑top is the standard for welding into 5S1P or 5S2P 18V/20V packs.

4. High‑Power Portable Fans & Industrial Cooling
Large fans that draw 10–25A on high speed run powerfully and consistently. The 4200mAh capacity provides hours of strong airflow on job sites or during outdoor events.

5. DIY High‑Current Power Banks & Portable Inverters
Build a compact power station that can fast‑charge multiple devices or run a small AC inverter. The high drain rate ensures stable output under heavy loads.

6. Electric Scooters & Light EVs (Small Packs)
For small electric scooters or hoverboards using 21700 packs, the P42A is the premium choice for rebuilding with maximum current and capacity.

FAQ

Q1: Can the P42A really handle 45A continuously?
A: Yes. Molicel rates the INR-21700-P42A for a genuine 45A continuous discharge. It’s widely regarded as one of the best high‑drain 21700 cells on the market, trusted by flashlight enthusiasts, drone racers, and tool rebuilders worldwide. It can pulse even higher for short bursts.

Q2: Why is this battery unprotected and only available as a flat top?
A: High‑drain cells like the P42A are designed without protection PCBs to minimize length and internal resistance — both critical for high‑current applications. The flat‑top terminal is the universal standard for enthusiast flashlights, drone sleds, and spot‑welded packs. It’s safe when used with a quality 4.2V charger and in devices that have built‑in low‑voltage cutoff. The cell’s own PTC, vent, and CID provide passive safety.

Q3: Will this flat‑top cell work in a device that originally used a button‑top battery?
A: It depends. Many high‑performance flashlights and tool packs are designed for flat‑top cells. If your device has a spring‑loaded positive contact with a physical reverse‑polarity ring, a button top may be required to make contact. Check your device manual; if it specifies “flat top” or “unprotected flat top,” the P42A is the correct choice.

Q4: Can I use these 21700 cells in a device designed for 18650?
A: No. A 21700 cell (21mm × 70mm) is larger than an 18650 (18mm × 65mm). Your device must explicitly support the 21700 form factor. Never force a 21700 into an 18650 tube.

Q5: How hot does the P42A get at 45A continuous?
A: With an ultra‑low internal resistance of ≤14mΩ, heat generation is remarkably well‑managed. The cell will become warm but stays within safe operating limits. Allow cooling between heavy discharge runs for maximum longevity.

Q6: Can I charge the P42A at 4.2A?
A: Yes, 4.2A (1C) is the maximum charge current. For best cycle life, we recommend the standard 2.1A (0.5C) rate. Fast charging generates more heat and may slightly accelerate long‑term capacity fade.

Q7: How should I store the spare cell?
A: Keep it in a plastic battery case away from metal objects and moisture. For storage longer than one month, bring the voltage to about 3.6–3.7V (roughly 50% charge). Check every 3 months and recharge if below 3.0V. Never store fully depleted.

Q8: Can I bring these batteries on an airplane?
A: Yes. At ~15.5Wh per cell, it’s well under the 100Wh IATA limit for carry‑on luggage. Insulate the terminals and carry in hand luggage.