A coin cell battery is a small, flat, circular battery that is often used as a power source for devices that require a button battery such as calculators, cameras, watches, and other electronic devices. Coin cell batteries are also commonly referred to as button batteries, disc batteries, or even watch batteries since they are often used in watches. Coin cell batteries come in a variety of sizes and voltages, and they usually have a shelf life of 3 to 5 years. As their name suggests, they are called “coin cells” because they are shaped similarly to a coin and have a round, flat design. Coin cell batteries have a number of advantages: They are lightweight, small, and easy to transport, and they can last for 3-5+ years even when not used.