Electronics » Batteries, 18650 Lithium Cells

Lithium 18650 cells are a specific, standardized size of rechargeable lithium-ion battery. They are widely used across various electronics and energy storage systems due to their high energy density and consistent power output.

Key Characteristics and Specifications

The name "18650" refers to the cell's physical dimensions:

  • 18: 18 mm (millimeters) in diameter

  • 65: 65 mm in length

  • 0: Indicates a cylindrical cell shape.

Feature Typical Specification
Chemistry Most commonly Lithium-ion (Li-ion), though other lithium-based chemistries exist (like LiFePO4).
Nominal Voltage Typically 3.6V or 3.7V. This is much higher than standard alkaline or NiMH AA batteries (1.2V-1.5V).
Full Charge Voltage 4.2V.
Capacity (mAh) Ranges from around 1,500 mAh up to 3,500 mAh or more, depending on the specific cell design and intended use (high-capacity vs. high-drain).
Discharge Rate Varies significantly; some are designed for high-drain applications (power tools, electric vehicles) and can handle high continuous current.
Design Available as unprotected (intended for use in battery packs with external safety systems) and protected (with a small built-in circuit board for overcharge/discharge safety, making them slightly longer).

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