If you're buying a new battery for your boat, you'll usually have three broad categories to consider: Traditional lead-acid Absorbed glass mat (AGM) Lithium iron phosphate (LiFePO4) These batteries exist on a spectrum, with lead-acid batteries being the most affordable, most difficult to maintain, and shortest lasting. At the other end of the spectrum, lithium batteries are by far the most expensive and long-lasting option. That leaves AGM batteries in the middle position, but are these batteries a genuine "