The three main types of batteries used in RC boats are lead-acid, nickel-cadmium, and nickel-metal-hydride. Lead-acid batteries are the most common type used in RC boats. They are inexpensive and have a long life, but they are also the heaviest type of battery. Nickel-cadmium batteries are lighter than lead-acid batteries but are more expensive and have a shorter life. Nickel-metal-hydride batteries are the most lightweight but are also the most costly.