Renata 321

RATED voltage is the voltage on the nameplate - the "design point" for maximum power throughput and safe thermal operation.

A battery is a device that stores chemical energy, and converts it to electricity. This is known as electrochemistry and the system that underpins a battery is called an electrochemical cell. A battery can be made up of one or several (like in Volta's original pile) electrochemical cells.

The most common lithium-ion cell is the 18650 (the numbers define the physical dimensions and shape as follows: 18mm in diameter, 65mm long and the 0 means it has a round cross-section) which is due to its widespread use in laptop battery packs.