A boat Marine battery is a type of rechargeable battery that is used to provide electrical power to the various systems and appliances on a boat. It is typically a deep cycle battery, which means that it is designed to be discharged and recharged repeatedly, as opposed to a car battery, which is designed to provide a burst of power for starting the engine and then is recharged by the alternator as the engine runs.

Boat marine batteries come in various sizes and types, including flooded lead-acid, sealed lead-acid, and lithium-ion. Flooded lead-acid batteries are the most common type and consist of a series of lead-acid cells that are filled with an electrolyte solution. Sealed lead-acid batteries are similar, but they are sealed and do not require regular maintenance. Lithium-ion batteries are newer and more expensive, but they offer higher energy density and longer lifespan than lead-acid batteries.

Boat batteries are used to power a variety of systems and appliances on a boat, including the engine starter, lights, navigation equipment, and appliances such as refrigerators and microwaves. It is important to choose the right type and size of boat battery for the specific needs of the boat and to ensure that the battery is properly maintained and charged.