For battery cells, review the product description for real-world current recommendations, testing notes, and application guidance. Manufacturer maximum ratings should be treated as limits, not the best target for long-term pack health.
Description
Reliance RS40 21700 Cell – 4000mAh – High-Drain Tabless Lithium-Ion Battery - Check availability
Continuous discharge: 70A
The Reliance RS40 21700 4000mAh is a high-drain lithium-ion cell built for applications that need very high current delivery, low internal resistance, and strong 21700-format performance.
With 4000mAh capacity, 3.60V nominal voltage, 14.4Wh nominal energy, ≤4.0mΩ AC impedance, and up to 70A continuous discharge (with 80°C temperature cut-off), this cell is well suited for power tools, electric mobility platforms, robotics/AGV systems, and other high-output battery packs.
Reliance positions the RS40 within its high-rate large cylindrical cell lineup, emphasizing fast charging, high-power output, and wide-temperature operation. It is best matched to properly engineered battery packs or devices with appropriate protection and thermal management.
Specifications:
| Model | Reliance INR21700-RS40 |
| Size | 21700 |
| Nominal Capacity | 4000mAh |
| Nominal Energy | 14.4Wh |
| Nominal Voltage | 3.60V |
| Max Voltage | 4.20V |
| Min Discharge Voltage | 2.50V |
| Max Continuous Discharge | 70A (with 80°C temperature cut-off) |
| Continuous Discharge Current | ≥10C without cutoff at 80°C |
| Standard Charge Current | 2.0A (0.5C) CC/CV to 4.20V, 100mA cut-off |
| Rate Charge | 8A (2C) CC/CV to 4.20V, 100mA cut-off |
| Max Continuous Charge Current | 14A (3.5C) CC/CV to 4.20V, 100mA cut-off |
| Standard Discharge | 0.8A (0.2C), 2.50V cut-off |
| Chemistry | Li-ion (INR, Ni-rich cathode / Si-anode architecture) |
| Positive Terminal | Flat Top |
| Protected | No |
| Rechargeable | Yes |
| AC Impedance | ≤4.0mΩ at 1kHz |
| Approx. Weight | ≤67.0g |
| Dimensions | ≤21.35mm diameter × ≤70.30mm height |
| Operating Temperature | Cell surface — Charge: 0°C to 60°C / Discharge: -20°C to 80°C |
| Storage Condition | 1 year: -20°C to 25°C / 3 months: -20°C to 45°C / 1 month: -20°C to 60°C |
| Cycle Life | ≥60% capacity retention after 400 cycles under stated RT test conditions (8A charge / 40A discharge or 14A charge / 30A discharge); also ≥80% after 200 cycles at 0°C with 8A charge / 10A discharge |
| Datasheet | Datasheet |
Applications:
- ✅ High-Performance E-Bikes
- ✅ Electric Scooters
- ✅ Power Tools
- ✅ Heavy-Duty Battery Packs
- ✅ Custom 21700 Builds
DIY500AMP.COM Design – High-Drain, Pack-Ready Power
⚠️ Safety Warning for Lithium-Ion Battery Usage
This is a high-power lithium-ion cell. Mishandling, short-circuiting, overheating, overcharging, puncture, or physical damage can cause fire, burns, or serious injury.
Use only in a properly engineered battery pack or device with suitable protective circuitry, current limits, and temperature monitoring. Follow the stated voltage, current, and temperature limits, and avoid charging below 0°C unless operating under a validated low-temperature procedure.
Important Usage Guidelines:
- Use in Properly Engineered Packs or Devices
- Use with Protective Circuitry / BMS
- Observe 4.20V Max Charge Voltage
- Observe 2.50V Discharge Cut-Off
- Respect 80°C Thermal Cut-Off on High-Current Discharge
- Do Not Use if Cell Wrap or Insulator Ring Is Damaged
Orders ship from Florida when inventory is available. Lithium-ion cells require proper handling, protected packs, correct chargers, and safe storage. Do not solder directly to battery terminals.
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I purchased some of these tabless cells to try on my 1S 3" HD Toothpick drone build, and, albeit a bit heavy for 1S, it flies pretty well. Not a freestyle monster, but an endurance beast with decent send. These cells shrug off the demands of a BETAFPV Matrix HD AIO flight controller/12A ESC and some 1202.5 11000KV motors. I'm getting 15+ minutes of speedy flight time from a single cell trying not to go below 3.2V, and about 20+ minutes cruising. Love these cells and will definitely buy more when time comes, only from DIY500AMP, who are terrific!
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