The first step in installing a marine dual-battery system is choosing a selector switch designed for two batteries. Choose a switch that can handle the amperage of the engine when it's being started. Additionally, ensure the switch has a lock for security against boat theft or a field disconnect circuit for protecting the alternator in case you turn off the batteries while the engine is running.Continue Reading
Choose a second marine battery that meets the engine's specifications and complies with Coast Guard and ABYC standards. Install the second battery, securing it using a bracket or a tie-down. Next, cover the positive terminal using a non-conductive boot.
Choose a surface with sufficient space for the selector switch. Place the switch as close the batteries as possible, and ensure it's safe from sprays. Next, connect cables from the positive terminals of the two batteries to the input posts at the back of the switch and the positive cable from the engine to the output post of the switch. Additionally, connect the positive accessory wire to the output post.
Connect the negative terminals of the two batteries using a crossover cable. Finally, connect the negative cable lug from the engine and the negative accessory wire to any of the negative battery posts.Learn more about Vehicles