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IFR21700 / LiFePO₄ | 3.2V Batteries – Inherently Safe, Ultra-Long Cycle Life 3.2V Cylindrical Cells
Welcome to our IFR21700 / LiFePO₄ (3.2V) collection. The IFR21700 is the Lithium Iron Phosphate (LiFePO₄) variant of the 21700 cylindrical format. It trades slightly lower energy density for unmatched safety characteristics and exceptional cycle life. With a nominal voltage of 3.2V (fully charged at 3.65V) and a typical capacity range of 1800mAh to 3000mAh, these cells are rated for 2,000 to 4,000+ full charge/discharge cycles. IFR21700 batteries are the definitive choice for solar energy storage, medical equipment, UPS backup systems, emergency lighting, and any application where safety and total cost of ownership take precedence.
What Is an IFR21700 / LiFePO₄ Battery?
The IFR21700 designation breaks down as follows: "I" = built-in lithium-ion (rechargeable), "F" = Iron (Fe, LiFePO₄ chemistry), "R" = Round (cylindrical), and "21700" = 21mm diameter × 70mm length. Unlike standard NMC 21700 cells, IFR21700 operates on a 3.2V nominal platform with a full charge voltage of 3.65V, requiring a dedicated LiFePO₄ charger.
Core Advantages
- Inherently Safe – No Thermal Runaway: LiFePO₄ is the most thermally stable lithium-ion cathode material available. It passes nail penetration, overcharge, crush, and short-circuit tests without catching fire or exploding, making it the safest choice for indoor, personal, or unattended installations.
- Ultra-Long Cycle Life: Rated for 2,000–4,000+ full cycles (≥80% capacity retention). This translates to a service life 3 to 8 times longer than standard NMC 21700 cells, dramatically reducing lifetime replacement costs in stationary storage applications.
- Flat Discharge Curve: Maintains a consistent 3.2V output throughout the majority of the discharge cycle, delivering stable voltage to your device until near-full depletion.
- Wide Operating Temperature: Performs reliably from -20°C to 60°C during discharge, with excellent high-temperature tolerance unmatched by standard Li-ion. Charging range: 0°C to 45°C (select cells support -10°C charging).
- Low Self-Discharge: Loses only 2–3% charge per month in storage, making IFR21700 ideal for emergency backup equipment and seasonal-use devices.
- Environmentally Friendly: Contains no cobalt and no toxic heavy metals. LiFePO₄ is one of the most sustainable lithium-ion chemistries available.
IFR21700 vs. NMC 21700 vs. Protected 21700
| Parameter | IFR21700 / LiFePO₄ (This Collection) | NMC 21700 | Protected 21700 |
|---|---|---|---|
| Nominal Voltage | 3.2V | 3.6V–3.7V | 3.7V (NMC core) |
| Full Charge Voltage | 3.65V ±0.05V | 4.20V ±0.05V | 4.2V (PCB cutoff 4.25V) |
| Discharge Cut-off | 2.0V–2.5V (2.5V recommended) | 2.5V–2.8V | 2.5V–2.9V (PCB enforced) |
| Typical Capacity | 1800mAh – 3000mAh | 3000mAh – 5000mAh | 4000mAh – 5000mAh |
| Max Continuous Discharge | 3A – 10A | 8A – 45A | 8A – 10A |
| Cycle Life | 2,000–4,000+ cycles | 500–1,000 cycles | 500–800 cycles |
| Safety Profile | Excellent (inherently safe) | Good (requires protection) | Built-in 4-layer protection |
| Best For | Solar storage, medical, safety-critical | High-energy/power consumer & industrial | Consumer flashlights, DIY kits |
Popular IFR21700 / LiFePO₄ Cell Models – Quick Reference
| Model | Brand | Nominal Capacity | Continuous Discharge | Internal Resistance | Recommended Application |
|---|---|---|---|---|---|
| IFR21700-20E | EVE / Others | 2000mAh | 3A–5A | ≤30mΩ | Solar street lights, emergency lighting |
| IFR21700-25E | EVE / Others | 2500mAh | 3A–5A | ≤30mΩ | Medical devices, UPS backup |
| IFR21700-30E | EVE / Others | 3000mAh | 5A–10A | ≤25mΩ | Portable energy storage, portable medical |
| IFR21700-30HP | EVE / Others | 3000mAh | 10A | ≤20mΩ | Higher drain needs, 3.2V-compatible power tools |
| LiFePO₄ 21700 3.2V | Custom / OEM | 1800mAh–3000mAh | 3A–10A | 20–35mΩ | 3.2V device replacement and pack assembly |
Note: Exact specifications are listed on individual product pages.
Typical Specifications (IFR21700 / LiFePO₄)
| Specification | Typical Values |
|---|---|
| Nominal Voltage | 3.2V |
| Full Charge Voltage | 3.65V ±0.05V |
| Discharge Cut-off Voltage | 2.5V (recommended) |
| Capacity Range | 1800mAh – 3000mAh |
| Continuous Discharge Current | 3A – 10A (grade dependent) |
| Max Pulse Discharge Current | 10A – 20A |
| Cycle Life (to 80% capacity) | 2,000 – 4,000 cycles |
| Operating Temperature | Charge: 0°C~45°C / Discharge: -20°C~60°C |
| Internal Resistance | 20mΩ – 35mΩ |
| Cell Weight | Approx. 60–70g |
| Dimensions | Diameter 21.0mm–21.5mm × Length 70.0mm–71.0mm |
Typical Applications
| Application | Why IFR21700 / LiFePO₄ |
|---|---|
| Solar Energy Storage / Off-Grid Systems | 4,000+ cycle life meets daily cycling; thermal safety for indoor/outdoor installs |
| UPS / Backup Power Systems | Long standby life, stable voltage, safe for unattended operation |
| Medical Devices (Monitors, Infusion Pumps) | No fire/explosion risk; extended service intervals reduce maintenance |
| Emergency Lighting / Exit Signs | Wide temperature tolerance; reliable after years of float charging |
| Security Systems / Remote Sensors | Low self-discharge; safe for long-term, unsupervised deployment |
| DIY Powerwalls / Home Energy Storage | Easy series/parallel configuration; inherently safe chemistry |
| Mobility Scooters / Electric Wheelchairs | Safe around users; excellent deep-cycle endurance |
| RC Models (LiFePO₄-Ready) | Safer alternative to LiPo; flat discharge for consistent throttle response |
| 12V Lead-Acid Replacement Packs | 4S IFR21700 yields 12.8V nominal—direct drop-in for 12V lead-acid |
⚠️ Critical Compatibility Warning – Not Interchangeable with 3.7V Cells
IFR21700 LiFePO₄ cells are NOT drop-in replacements for standard 3.7V NMC 21700 batteries.
- Voltage Mismatch: The nominal 3.2V and full charge 3.65V differ significantly from the 3.7V/4.2V of NMC cells. Devices designed for 3.7V will likely shut down prematurely or operate incorrectly.
- Charger Requirement: Use ONLY a LiFePO₄-specific charger with a 3.65V cut-off voltage. Charging an IFR cell with a standard 4.2V Li-ion charger will cause irreversible overcharge damage and poses a safety hazard.
- Device Compatibility: Ensure your device is explicitly rated for or configurable to 3.2V LiFePO₄ chemistry. Many flashlights, medical instruments, and industrial controllers offer this option.
For devices requiring 3.7V operation, please refer to our NMC 21700 or Protected 21700 collections.
Why Choose Our IFR21700 / LiFePO₄ Batteries?
- Genuine Grade-A Cells: Sourced from reputable LiFePO₄ manufacturers with full traceability. No recycled or B-stock cells.
- Verified Performance: Every batch is tested for actual capacity, internal resistance, and cycle retention. No exaggerated ratings.
- Protected Options Available: Raw cells for professional pack assembly, with optional PCM integration for consumer safety.
- Precision Cell Matching: Capacity and voltage matching services for multi-cell series packs (2S, 4S, 8S, etc.) to ensure pack consistency.
- Flexible Quantities: Single-cell retail, multi-packs, and wholesale bulk pricing available.
- Certified & Documented: CE, RoHS, UN38.3 certified. MSDS and full export documentation provided.
- Technical Support: Expert guidance on LiFePO₄ system design, BMS selection, and charger compatibility.
👇👇👇 Browse the product list below to select the right IFR21700 / LiFePO₄ cell for your safety-critical, long-life application. For custom battery pack assembly or volume pricing, contact our engineering support team.
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