A boat's electrical system starts with a battery that will supply the electricity for the boat. The system is usually 12 volt DC (direct current), but can be 6 volt, 12 volt or 24 volt depending on how many and what type of batteries the system is designed for. For this article, the system discussed is a 12 volt system.
RV Batteries for Boondocking They are made to match the load requirements of a boat, they are usually sealed and leak-proof, and are often a dual purpose high load deep cycle type.