2-Pack EVE 21700-40P 4000mAh 3.7V Flat Top Battery – 35A Continuous / 40A Pulse for Drones, Power Tools & RC Cars

Double the Power, Double the Endurance
This 2‑pack of EVE 21700‑40P cells delivers the ultimate high‑drain solution for your most demanding devices. Each cell combines a genuine 4000mAh capacity with a ferocious 35A continuous discharge and the ability to pulse up to 40A for instantaneous surges. Whether you’re building a high‑performance FPV drone pack, rebuilding a cordless drill battery, or powering a 1/8 scale RC truggy, these flat‑top cells provide the relentless current and meaningful runtime that ordinary batteries simply cannot match. The two‑pack configuration means you always have a spare ready to swap, keeping your gear in action when it matters most.

Why EVE 21700‑40P? The Perfect High‑Drain Flat‑Top
The EVE 40P is engineered specifically for applications that demand extreme current without compromising safety or cycle life. Using advanced INR (Nickel‑Manganese‑Cobalt) chemistry, it achieves an ultra‑low internal resistance of ≤14mΩ, minimizing voltage sag even under sustained heavy loads. At a full 35A draw, the voltage drop is a mere 0.49V, ensuring your drone motors maintain peak RPM, your power tool doesn’t stall under torque, and your RC car accelerates with ferocious speed. The cell’s flat‑top design is the universal standard for high‑current devices: it mates perfectly with pogo‑pin contacts in drone battery trays, recessed flat pads in power tool packs, and nickel strips for spot‑welded custom builds. There is no raised button to interfere with tight‑fitting compartments or to create uneven pressure during pack assembly.

Unprotected by Design — Pure, Unfiltered Current
Like all high‑performance cylindrical cells, the EVE 40P is supplied as an unprotected bare cell. We intentionally omit the external protection PCB to keep the overall length at the standard 70.0mm — critical for fitting into compact drone frames, densely packed tool battery shells, and RC battery trays. Removing the PCB also eliminates the extra electrical resistance that can limit current during high‑drain pulses, ensuring your devices get every single amp they demand. Naturally, this design requires responsible use: always charge these cells with a quality charger that terminates at exactly 4.2V, and only install them in devices that have built‑in low‑voltage cutoff — a feature already present in virtually all modern drones, brushless power tools, and RC electronic speed controllers. The cell itself incorporates a built‑in PTC thermistor, resealable safety vent, and CID for passive multi‑layered protection.

Where 35A Continuous and 4000mAh Shine
The 4000mAh capacity (approximately 14.8 watt‑hours) provides a meaningful runtime advantage over lower‑capacity high‑drain cells. In a racing drone, this translates to competitive flight times without sacrificing the instant throttle response that the 35A discharge enables. A cordless impact driver built with these cells will drive hundreds of screws on a single charge. An RC monster truck will tear through a full heat and still have power to spare. Even in high‑power portable fans or DIY power banks, the combination of high current and decent capacity means you can run demanding loads without voltage collapse. With two cells in the pack, you can build series or parallel configurations or keep a fully charged spare ready for zero‑downtime operation.

Long‑Term Reliability and Safety
The EVE 40P is rated for over 500 full charge/discharge cycles while retaining at least 70% of its initial capacity. Its low self‑discharge rate means you can store spare cells at the recommended 3.6–3.7V for months, and they will still be ready when you need them. The nickel‑plated steel can resists corrosion, impacts, and the vibrations typical of drones, power tools, and RC vehicles. Built‑in passive safety layers — a PTC thermistor, a resealable safety vent, and a CID (Current Interrupt Device) — provide robust protection against over‑current, over‑pressure, and short circuits.

Key Features

• 2‑Pack Value: Twice the Power
  Two identical EVE 40P cells. Keep one in your device and one fully charged — ideal for extended missions, back‑to‑back heats, or all‑day job site use.

• 35A Continuous / 40A Pulse High‑Drain Output
  Genuine high‑rate discharge handles the most demanding drones, power tools, and RC models without voltage sag. Instantaneous torque and full‑throttle acceleration are always available.

• 4000mAh Genuine Capacity (14.8Wh per cell)
  Provides a balanced runtime for high‑current applications — competitive drone flights, dozens of screws driven, or full RC heats.

• Unprotected Flat‑Top Design
  Standard 70mm length and flush positive terminal ensure perfect fit in tight battery compartments, pogo‑pin contacts, and spot‑welded packs. Eliminates added PCB resistance for maximum power delivery.

• Ultra‑Low Internal Resistance (≤14mΩ)
  Voltage drop at 35A is only ~0.49V. Minimal heat generation and sustained performance even under extreme loads.

• Stable INR (NMC) Chemistry
  Maintains a consistent 3.7V nominal voltage with a flat discharge curve. Light output, motor RPM, and torque stay predictable throughout the discharge.

• 500+ Cycle Life & Low Self‑Discharge
  Recharge over 500 times with minimal capacity fade. Holds charge for months in storage 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. Designed to handle the vibrations, crashes, and harsh conditions of drones, tools, and RC vehicles.

Technical Parameters

Applications

1. Racing Drones & FPV Quadcopters
Build a 4S or 6S high‑discharge pack for freestyle, racing, or cinematic drones. The 35A continuous output feeds brushless motors with the instant punch needed for hairpin turns and explosive climbs, while the flat‑top terminals make spot‑welding clean and reliable.

2. Cordless Power Tools (Rebuilds & Upgrades)
Replace worn‑out cells in high‑torque drills, impact drivers, circular saws, and angle grinders. The 40P handles the 20–35A startup spikes of professional tools, and the 4000mAh capacity provides useful runtime. The flat‑top design is the standard for welding into 5S1P or 5S2P 18V/20V packs.

3. RC Cars, Trucks & Boats
Build a 2S or 3S pack for 1/10 and 1/8 scale vehicles. The relentless current delivery means explosive acceleration, strong mid‑range torque, and enough capacity for a full race heat or extended bashing session.

4. High‑Power Portable Fans & Cooling Devices
Large industrial‑grade fans that draw 10–20A run effortlessly on these cells. The 4000mAh capacity provides hours of strong airflow on job sites, in workshops, or during outdoor events.

5. DIY High‑Current Power Banks & Portable Inverters
Build a portable power station that can fast‑charge multiple devices or run a small AC inverter. The high drain rate ensures stable output, and the 2‑pack gives you the core cells to start your project.

6. Electric Scooters & Light EVs (Small Packs)
For small electric scooters or hoverboards that use 21700 packs, the 40P is an excellent choice for rebuilding with high‑performance cells that deliver both current and capacity.

FAQ

Q1: Is the 40P really capable of 35A continuously? How does it compare to the 50E or 40T?
A: Yes, the EVE 21700-40P is rated for 35A continuous discharge, with pulse capability up to 40A. It sits between the high‑capacity 50E (5000mAh, 10A) and the ultra‑high‑drain 40T (4000mAh, 35A, but higher pulse). The 40P offers a balanced 4000mAh with strong 35A continuous — perfect for users who need both high current and decent runtime.

Q2: Why is this battery unprotected and only available in flat top?
A: The EVE 40P is designed for high‑drain applications where a protection PCB would add unwanted length and resistance, and where a button top would interfere with tight compartments or spot welding. The flat‑top, unprotected design is the universal standard for drones, power tool packs, and RC models. It’s completely 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 protection.

Q3: Can I use this flat‑top cell in a device that originally used a button‑top battery?
A: It depends on the device. Many high‑performance drones, tool packs, and RC vehicles are specifically designed for flat‑top cells. If your device’s positive contact is a spring with a physical reverse‑polarity ring, a button top may be required to bridge the gap. Check your device manual: if it specifies “flat top” or “unprotected flat top,” these 40P cells are the correct choice.

Q4: Can I use these 21700 cells in a device designed for 18650?
A: No. A 21700 cell (21mm × 70mm) is physically 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 40P get at 35A continuous?
A: With an ultra‑low internal resistance of ≤14mΩ, heat generation is well‑managed. The cell will become warm — typically reaching 65–75°C after several minutes of sustained 35A — but stays within safe operating limits. Allow cooling between heavy discharge runs for best longevity.

Q6: Can I charge these batteries at 4A?
A: Yes, 4A (1C) is the maximum charge current. For optimal cycle life, we recommend the standard 2A (0.5C) rate. Fast charging generates more heat and may slightly reduce long‑term capacity.

Q7: How should I store the spare cell?
A: Keep it in a plastic battery case or silicone sleeve, 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 the voltage drops below 3.0V. Never store a fully depleted cell.

Q8: Can I bring these batteries on an airplane?
A: Yes. Each cell is approximately 14.8Wh, well under the 100Wh IATA limit for carry‑on luggage. Insulate the terminals and carry them in your hand luggage.