Spark Logic

18650 lithium-ion cell pinout

18650 identifies a cylindrical form factor. The Molicel INR-18650-P28A is one example, with a 3.6 V nominal voltage and 2.8 Ah typical capacity.

Bare cylindrical cell

2 contacts Current package
Protected pack connector 2 contacts

Molicel and Honcell · Molicel INR-18650-P28A · 18.6 mm maximum diameter × 65.2 mm maximum height.

Bare cylindrical cell pinout

Bare cylindrical cell
Side view with the insulated positive cap to the left. The map uses 1 and 2 as terminal identifiers.
Selected pin details

1 · +

Positive terminal · Power

The positive cap sits at the end with the insulating ring. The ring separates it from the surrounding can.

Molicel P28A datasheet, p. 1

Electrical limits · Link to this pin

All 2 pins

PinSignalDirectionFunction
1+ Positive terminalPositive terminal The positive cap sits at the end with the insulating ring. The ring separates it from the surrounding can.
2− Negative terminalNegative terminal The flat bottom is negative. Keep the steel can and positive cap insulated from one another.

Signal assignments

Cell polarity

The positive cap and negative bottom are opposite ends of the cylinder. A metal object touching both polarities can short the cell. Use a factory-assembled protected pack for the wiring examples.

Electrical limits

ParameterLimitConditions and source
Nominal voltage3.6 V3.6 V Cell model INR-18650-P28A. Molicel P28A datasheet, p. 1
Capacity2.8 Ah typical · 2.7 Ah minimum2.8 Ah typical · 2.7 Ah minimum Cell figures. Refer to the manufacturer’s curves for current and temperature effects. Molicel P28A datasheet, p. 1
Characterized voltage endpoints4.2 V charge · 2.5 V discharge4.2 V charge · 2.5 V discharge Cell manufacturer’s values. Pack thresholds and equipment operating limits depend on the protected assembly. Molicel P28A datasheet, p. 1
Maximum cell dimensionsØ 18.6 mm × 65.2 mmØ 18.6 mm × 65.2 mm The protected pack uses a different mechanical envelope. Molicel P28A datasheet, p. 1

Models and documents

This reference covers the bare Molicel INR-18650-P28A and the separately documented Honcell HCC18650FC protected assembly. Check the exact manufacturer code for chemistry, voltage, capacity, load rating, protection and fit.

INR-18650-P28A
Industrial bare cell described in the Molicel product datasheet.