A deep cycle battery is a type of battery designed to provide sustained power over an extended period of time. Unlike a traditional car battery that is designed to deliver a quick burst of power for starting the engine, a deep cycle battery is built to discharge a large amount of its capacity over a longer period of time. Deep cycle batteries are commonly used in applications that require a reliable, long-lasting source of power, such as marine vessels, RVs, off-grid solar systems, and electric vehicles. They are also used in backup power systems for homes and businesses.