What is 18650 Battery?
So what exactly are the 18650 batteries? This naming convention refers to the lithium-ion battery cells are 18 mm, 65 mm, and circular in shape. The battery offers a balance between capacity, output, rechargeability, and dimensions that have made it one of the most common power sources for LED flashlights today.
As technology has advanced over the years, and especially in the last decade, the need for batteries that can compete with modern gadgets has led to the development of cells capable of longer runtimes, higher output, and better charging ability. One such development is the introduction of 18650 li-ion batteries that were originally used in laptops.
Understanding different li-ion specifications
Although some basic things like internal chemistry and size remain consistent between the 18650s, there are several options to realize.
Flat-top or key-top
The first and most important specs to consider when buying batteries for your device are whether or not they require a cell-top button.
Max Discharge rate
If you remember from high school physics, the voltage measuring the strength of the electric charge. Most 18650 batteries will have a voltage rating of 3.6 or 3.7V as an expected standard.
These specifications are less important than the first two, but still, one that can make a world of difference. Measured in milliamp hours, the battery capacity will help you measure the overall runtime may be on a flashlight or device.