A deep cycle battery is like a big cup of energy: it stores power so that you can use it when you need it. It's like a rechargeable battery in that you can use it over and over again, but it's made to take a deep discharge each time it's used. That means it can hold more energy, and it won't run out as quickly as a regular battery would. A deep cycle battery is often used in things like solar power systems, golf carts, and electric boats to store power so it can be used when the sun isn't shining or when you need the extra power.