SIDEWAYS THINKING

Marine lead-acid batteries must be mounted upright (terminals on top) in the boat to operate properly and prevent acid spillage from flooded-cell batteries. Yet a marine AGM (absorbed glass mat) battery contains no liquid acid, and so it can be mounted on its side without risk of malfunction or acid spills. While it might run to contrary to your intuition, keep this in mind when adding a boat battery or two in a confined space that hinders access to the top of the battery. Securing an AGM battery sideways might let you get to the terminals more easily.