18650 and 21700 are cylindrical lithium batteries that are widely utilized in our everyday lives and production processes. These two batteries are frequently employed in DIY projects such as charging banks and power tool battery packs. The term "18650" signifies a cylindrical battery with a diameter of 18mm, a height of 65mm, and a "0" indicating its cylindrical shape. Similarly, "21700" refers to a cylindrical battery with a diameter of 21mm and a height of 70mm. The number "0" again denotes its cylindrical form. Among these, 21700 is gaining popularity and is extensively used by Tesla in their electric cars. It offers a larger capacity than 18650 while being more cost-effective. Additionally, there are now available kits for 21700 lithium batteries, including charging banks and battery packs.
