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The Lowdown on Lithium Batteries

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Super Power

Experts say that batteries featuring lithium technology will outlast many of the boats they’re installed in.
Are they worth the extra money?

Whenever you’re on a boat, at least part of the time you’re probably looking around for something you’d want to improve, whether it’s related to performance, convenience, or comfort. Chris Bakken is one of the fortunate few who’s actually been able to act on one of his ideas.

Lithium-ion batteries have many advantages over traditional batteries, but up-front cost isn’t one of them.

For openers, he is a renewable energy startup and integration consultant who’s worked with lithium-ion technology in heavy-transportation applications such as buses and trucks. But coincidentally, he also happens to be a bareboat charterer who frequently finds himself on vessels that lack the battery power to run a blender and a windlass at the same time.

“So I took what I was doing in the bus world and decided we could do that in the yachting world,” Bakken explains. And today, he is the president of ARC3 Energy ( of Portland, Oregon, which makes SeaPack batteries based on lithium-ion technology. 

Lithium-ion batteries are so named because they have an intercalated lithium compound as the electrode material compared to lead in a typical Absorbed Glass Mat (AGM) battery. In a lithium-ion battery, lithium moves from the negative electrode to the positive one during discharge and then the process is reversed when the battery is charging. 

Lithium-ion batteries have a number of important advantages over competing technologies. Among other things, they are lighter than traditional lead-based batteries. An ARC3 Technologies SeaPack 12-volt, 400-amp-hour/24-volt, 200-amp-hour model weighs 146 pounds compared to a similar AGM lead-based battery which weighs 176 pounds. 

For many people, the weight savings is secondary to the efficiency edge that lithium technology holds over AGM. Bakken explains that a typical lead-type battery has three stages of charging. The first floods the battery with current. The second entails absorption, and the third is trickle charging. The problem is that under real-world conditions, once the battery is flooded, the lead plates inside can’t absorb the energy fast enough to handle all the current. More than half is typically burned off. Then the remaining charge needs to be trickled into the battery to eventually get it back to full capacity, a process that can take several hours.

A lithium battery, on the other hand, has only two charging stages: flood and trickle. When the alternator, generator, or battery charger sends energy to a lithium battery, it has the capacity to charge at more than 93 percent efficiency and often reaches capacity in little more than an hour’s time.

Because of this efficiency edge, lithium batteries enjoy a big advantage in how many usable kilowatt-hours a typical unit will produce. ARC3 Energy’s 12-volt, 400-amp-hour/24-volt, 200-amp-hour battery fits within the same footprint as a typical 8D battery. But it has four usable kilowatt-hours compared to a typical AGM that produces about one. 

Of course, nothing is perfect. Lithium-ion batteries are very expensive. The model I just described costs $5,900 (compared to $800 for a top-of-the-line AGM). That seems like crazy money until you consider that you’ll probably never have to replace the lithium model. “I’ll be the first to say these batteries will outlive the life of the boat they’re going into,” notes Bakken.

For you Internet fans worried about marine lithium-ion batteries blowing up after reading about batteries exploding in computers and cell phones, the batteries used in boats typically use lithium-iron phosphate, which makes them much more stable as a power source. “Accidents like those are not possible in iron-phosphate chemistry,” says Bakken. “You can punch a hole in one of our batteries and there will be no catastrophic failure. We’ve done it with a drill.”

One reason for the bigger price tag is that ARC3 Energy provides a sophisticated control system with every battery. Inside each is a circuit board that controls the input and output current of the battery. It links to a monitor that’s either handheld or installed at the helm of your boat. It won’t let too much current go in or out, thereby preventing battery damage. It also won’t let the battery’s voltage drop below 80 percent depletion. On the verge of such an event, a light on the monitor will blink indicating you need either to start the engines, fire up the generator, or activate your boat’s battery charger. 

As with any technology, there’s a learning curve to lithium-ion batteries that technicians and other marine-industry professionals are facing. Because of the power contained within, a lithium-ion battery will fry a typical jumper pack designed for an AGM battery. Also, because of the variations in chemistry and output, the two types can’t be used in parallel. They must be kept isolated.

Of course, ARC3’s is not the only lithium-ion marine battery technology on the market. Mastervolt (, Lithionics Battery, (, and Lithium Pros ( also sell lithium-ion-based batteries for marine and other applications.

Just remember. Choose any of these products and you’ll most assuredly have enough power to run your blender and your windlass at the same time.

This article originally appeared in the November 2012 issue of Power & Motoryacht magazine.