18650 LiFePO4 Battery 3.2V 1500mAh | IFR18650 LFP Cylindrical Cell

18650 LiFePO4 Battery — IFR18650 1500mAh 3.2V Cylindrical LFP Cell

The 18650 LiFePO4 battery (model IFR18650) puts lithium iron phosphate chemistry in the world’s most common cylindrical format: 18 mm in diameter, 65 mm in height, 1500 mAh at a 3.2 V nominal platform. It deliberately gives up energy density — an NCM 18650 stores two to two-and-a-half times the watt-hours — in exchange for the two properties daily-cycling and safety-critical systems actually buy: a cycle life specified at 2000+ cycles, and a chemistry that does not propagate thermal runaway. The IFR18650 is engineered for off-grid solar storage, cold-climate backup power, solar luminaires and AGV or robotics packs where the cell will be charged and discharged every day for years. CMX Battery supplies it with per-lot capacity, IR and OCV test data, OEM branding, and a downloadable datasheet.

Table of contents: Specifications · What Is a 18650 LiFePO4 Battery? · IFR vs INR 18650 · Charge & Discharge · Cycle Life & Safety · Applications · Stepping Up to IFR26650 · Certifications · OEM/ODM & Ordering · FAQ

18650 LiFePO4 Battery Specifications

Typical values below reflect the production standard for this format across established manufacturers; final parameters ship against the CMX controlled product specification.

What Is a 18650 LiFePO4 Battery?

A 18650 LiFePO4 battery is a rechargeable cylindrical cell whose designation encodes its geometry — 18 mm diameter, 65 mm height, cylindrical format — with lithium iron phosphate as the active chemistry. The IFR prefix is the IEC convention for cylindrical LFP cells (I = lithium-ion, F = iron phosphate, R = round), parallel to the INR prefix used for cylindrical NCM cells. The two share the same steel can but nothing else electrically: the IFR18650 sits on a 3.2 V nominal platform (3.65 V charge, 2.0 V discharge cut-off), while an NCM 18650 sits on 3.6–3.7 V (4.20 V charge, 2.75 V cut-off).

The cell is a sealed steel can with a CID safety vent; welding is permitted only on the top cap and bottom end, never on the side wall. Its flat 3.2 V discharge curve holds voltage nearly constant across most of the capacity range, which keeps inverter and LED driver input stable without a regulator stage.

IFR18650 vs NCM 18650: Chemistry Comparison

Both cells share the 18 × 65 mm envelope, so the choice is electrical. Use this table to confirm fitment before sampling.

For the high-energy 3.7 V platform and the full NCM capacity gradient, see the 18650 lithium battery series page. For the full cylindrical lineup, see the small cylindrical lithium cells overview.

IFR18650 Charge and Discharge Profile

Charging follows CC-CV on the LFP profile: constant current at the standard 0.2–0.5C rate until terminal voltage reaches 3.65 V, then hold at 3.65 V until current tapers below the cut-off threshold. Maximum charge current is 1C (1500 mA). Never charge an IFR18650 with a 4.2 V li-ion charger — the 3.65 V ceiling is a hard chemistry limit, and exceeding it damages the cell. Charge temperature is specified 0–45 °C for standard grades; low-temperature grades accept charge current down to −30 °C without external heating.

Discharging is rated 3C (4.5 A) continuous with 5C (7.5 A) for short pulses, to a 2.0 V cut-off; high-rate grades reach 10C continuous (15 A) for power-tool and AGV duty. Because the LFP voltage curve is flat, an 8S string (25.6 V nominal) or 4S string (12.8 V nominal) holds a nearly constant bus voltage through most of the discharge.

IFR18650 Cycle Life and Safety Performance

Cycle life is the reason to choose this chemistry: production cells are specified at 2000+ cycles to ≥80% capacity retention — roughly four to six times the cycle count of a standard NCM 18650. In an off-grid solar system cycling once per day, that is five or more years of service before capacity fades to the replacement threshold.

Safety testing covers over-discharge, overcharge, external short circuit, thermal abuse, drop, vibration and temperature shock — all with no fire, no explosion, no leakage. The LFP chemistry’s higher thermal runaway onset temperature makes it the lower-risk choice for densely packed assemblies, occupied spaces and safety-critical enclosures, and removes the thermal-runaway propagation concern in multi-cell series strings.

18650 LiFePO4 Battery Applications

Off-grid solar storage and portable power stations. The flagship application. An 4S or 8S IFR18650 string replaces lead-acid blocks in small off-grid systems: maintenance-free, no acid, flat 3.2 V-per-cell bus, and a cycle life that matches the daily charge-discharge duty of a solar installation.

Cold-climate backup power and electric mobility. Standard grades discharge to −20 °C; low-temperature grades deliver full discharge capability to −50 °C and accept charge current to −30 °C — removing the heated-enclosure and derating compromises that NCM packs require in Nordic, Canadian and Alaskan deployments.

Solar luminaires and street lighting. Fits the standard 18650 format; the 2000-cycle rating and low self-discharge suit unattended lighting that must survive seasonal storage.

AGV, robotics and unmanned vehicles. High-rate grades (10C continuous class) deliver the burst current for drive and steering duty, with the chemistry’s thermal stability simplifying pack thermal design in enclosed chassis.

UPS and industrial backup. Long service life plus flat discharge curve keeps backup rails stable without conditioning stages; per-lot test data simplifies incoming QC for regulated product lines.

Stepping Up: When to Choose the IFR26650 Instead

If your pack energy target outgrows what the 18 mm format can deliver, the 26650 LiFePO4 battery (IFR26650) doubles the capacity in the same 3.2 V chemistry and the same 3.65 V charge ceiling — 3000 mAh and ≈ 9.6 Wh against 1500 mAh and ≈ 4.8 Wh. Same 2000+ cycle life at full depth of discharge, same UN38.3 and IEC 62133-2 documentation, and roughly 40 mΩ less internal resistance, which matters when packs run at high continuous current.

The trade is mechanical: the IFR26650 is about 8 mm wider and twice the mass, so it suits packs whose housing accepts the larger can. Where the 18 mm envelope is fixed, the IFR18650 stays the right cell. Both formats ship Grade-A with OEM/ODM customization, BMS options and per-lot test data. Full IFR26650 specifications are on the dedicated page — send your mechanical envelope and pack voltage and we will confirm fitment either way.

Certifications and Shipping Compliance

Every IFR18650 ships against the documentation compliance teams ask for first: UN38.3 (the UN Manual of Tests and Criteria test summary required for lithium transport by air and sea), MSDS, IEC 62133-2 cell safety compliance, CE and RoHS declarations, and REACH documentation for EU-bound programs. Lot-level documentation — capacity, internal resistance and open-circuit voltage per cell — accompanies each shipment so incoming QC starts from data rather than sampling. For the full certification scope, see our lithium battery certifications and compliance page.

OEM/ODM Customization and Ordering

CMX Battery supplies the IFR18650 for OEM programs: welded tabs or connectors to your drawing, shrink-wrap or label branding with your model number, BMS integration for pack orders from 12 V to 48 V, and packaging configured to your line. Cells ship at partial SOC with per-lot test data. Samples are available for bench validation before volume commitment; minimum order quantities, lead times and per-lot test-data format are confirmed with your quotation, which comes back within 24 hours. Warranty is one year from date of shipment against manufacturing defects.

Frequently Asked Questions

What is a 18650 LiFePO4 battery?
A 18650 LiFePO4 battery is a rechargeable cylindrical LFP cell (Ø18 × 65 mm, 1500 mAh, 3.2 V nominal). The IFR18650 is the LiFePO4 counterpart of the NCM 18650 — same envelope, different chemistry and voltage platform.

What is the difference between IFR18650 and a regular 18650?
Chemistry and voltage: IFR18650 is LiFePO4 at 3.2 V nominal (3.65 V charge) with 2000+ cycle life; a regular 18650 is NCM at 3.6–3.7 V (4.20 V charge) with more capacity but shorter cycle life. They are not interchangeable in the same circuit.

What is a 18650 LiFePO4 battery used for?
Off-grid solar storage, cold-climate backup power, solar luminaires, AGV and robotics packs, UPS backup, and 12.8 V or 25.6 V strings built from 4S or 8S configurations.

How do you charge a 18650 LiFePO4 battery?
CC-CV to 3.65 V with taper cut-off; standard charge 0.2–0.5C, maximum 1C (1500 mA), charge window 0–45 °C. Never use a 4.2 V li-ion charger.

How long does an IFR18650 last?
Production cells are specified at 2000+ cycles to ≥80% capacity retention — in daily-cycling solar service that translates to five or more years.

Can IFR18650 batteries work in cold weather?
Standard grades discharge to −20 °C. Low-temperature grades deliver full discharge to −50 °C and accept charge current to −30 °C, removing the need for heated enclosures in cold-climate deployments.

Is the 18650 LiFePO4 available with OEM branding?
Yes — welded tabs or connectors, custom labels with your model number, BMS integration and tailored packaging are standard services, with per-lot test data on every shipment.

Request a Quote

Send your target voltage, capacity, continuous current and mechanical envelope — you will receive a datasheet-matched quotation, sample options and lead time within 24 hours.

Or email sales@cmxbattery.com. Download the typical specifications overview: IFR18650 Typical Specifications Overview (PDF). The controlled product datasheet is issued with your quotation on request.