Marine Power: Are Lithium Batteries the Best Choice?

They are lighter and stronger, but also way pricier. Here are the pros and cons.

September 19, 2025 By Frank Sargeant

Lithium batteries have a couple of huge advantages when they’re built right, which is why many serious boaters have invested in them despite the prices.

Lithium Battery Positives

The most obvious pro of a lithium battery is the extremely light weight, about one third of what a lead-acid battery of similar output weighs, or even less in the case of the 36-volt models that can replace three lead-acid 12-volt batteries. Less weight is particularly important in flats and bass boats, allowing them to float in less water and also run faster and/or use less fuel. They have obvious advantages for kayaks, as well.

And one 36-volt lithium battery takes about the physical space of one 12-volt lead-acid battery, so there’s also a big advantage in storage.

It’s also apparently true that the best lithium iron phosphate batteries, properly cared for, last 8 to 10 years—three or four times longer than the typical lead-acid battery. This is the critical factor when assessing whether they make economic sense—if you’re keeping your boat indefinitely, they do.

They run longer on a charge, and deliver full power almost right up to the point of shut-down. This is not only important for trolling motors, but also for the high-draw electronics many anglers use on their boats these days. They also charge a lot faster than lead-acid.

On big boats, some manufacturers are now installing multiple high-output lithium battery banks in place of a gasoline or diesel generator to supply the “house” with air-conditioning, lights and other electrical needs. The batteries produce no dangerous fumes, no noise, and weigh less than the generator they replace. The batteries are recharged while underway by the main engines, or at the docks by the usual shore power cord.

Some of the best include Bluetooth, allowing you to quickly check your remaining battery charge throughout the day via your smart phone.

Tracker Marine says their lithium iron phosphate batteries are good for 5,000 cycles vs. around 270 when comparing to a lead-acid battery, or 350 cycles for AGM. Other suppliers make similar claims.

Lithium Battery Negatives

There have been dramatic failures of lithium-cobalt batteries used in automobiles and other devices, resulting in fires that are very difficult to put out.

Note that lithium-iron-phosphate batteries are not the same thing, and present a very low risk of ignition not only per the builders but from independent agencies.

Lithium batteries are not approved as starting batteries for Yamaha or Suzuki outboards—but select models are OK for Honda and Mercury outboards so long as they meet the requirements of the particular outboard. (Note that Mercury likes lithium batteries so much that they bought ReLiOn in 2021.)

Lithium batteries (like all batteries) lose a lot of power in temperatures below freezing. The best include built-in heaters that prevent issues, but these add to the cost. They also lose efficiency if they get very hot, so it’s not wise to install them close to the exhaust system of an inboard or sterndrive boat.

Battery makers say amortized over 10 years or more—in which you would have replaced your lead acid batteries up to five times—the lithium batteries make a lot of sense. You pay more to start, but you don’t have to haul those heavy lead acid batteries out of the bilge before every other season for replacement. And you get better performance not only from the batteries but from your boat during the entire service period.

The warranty on some LiFEPO4 batteries is 11 years! Lead acid batteries have warranties from 12 to 36 months, typically, and sell for between $125 and $225. Absorbed Glass Mat or AGM batteries, maintenance free, are a step up in dependability and power, but are more expensive, with prices of $200 to $300 typically.

And prices of lithium batteries are coming down as competition heats up. Some 36-volt models are available for around $900 now, while they were as much as $1,300 a few years ago. Twelve volt LiFePO4 models are going for under $700 in some brands.

Bottom line is, if you expect to keep your boat at least 5 years, buying a set of lithiums is probably a good investment. And even if you plan to trade within a couple years, the advantages of lighter weight, smaller footprint and quicker charging may be worth paying extra for.