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Move over, lead-acid

Nov 1, 2017

Lithium-ion-based batteries gain wider acceptance

The 48-volt lithium-ion installation aboard Keith Underdown’s 44-foot catamaran Cat Ion.

The 48-volt lithium-ion installation aboard Keith Underdown’s 44-foot catamaran Cat Ion.

Managing a cruising boat’s DC electrical system can feel a bit like performing a juggling act. The demands of modern, power-hungry onboard amenities, such as refrigeration and watermakers, must be balanced against a bevy of charging sources: solar, wind, engine alternators and stand-alone generators. Any miscalculation can send the elaborate network crashing down.

Of course, the heart of it all is the house battery bank. Lead-acid flooded cell units were once the only choice; however, in recent years, other types of lead-acid chemistry, such as absorbed glass mat (AGM) and gel cells, have made significant inroads. And now, a small but growing minority of cruisers is opting for a different battery chemistry: lithium-ion, or Li-ion, the same technology that powers your cellphone.

Ken Jones and his family have been cruising the Caribbean aboard their Catalina 380 Aqua Vida since 2013. A year and a half ago, he needed to replace the house bank of several heavy and cumbersome 4D lead-acid batteries. At the time, Aqua Vida’s sole source of charging was the engine’s alternator. First, Jones decided to add 400 watts of solar panels. Then, a solar contractor steered him toward Clearwater, Fla.-based Lithionics, a pioneer in marine lithium-ion battery installations.

Jones had a lengthy conversation with the company’s engineering manager, Stephen Tartaglia. He even visited the Lithionics facility, and was duly impressed. “Based on [Stephen’s] explanation and with the technical information [available], we made our decision,” Jones said.

The system chosen for Aqua Vida relies on a computer developed by Lithionics that constantly monitors battery vitals and temperature. If it senses flow in or out of the batteries that exceeds acceptable parameters, it shuts down automatically. Jones said that’s happened twice aboard Aqua Vida, and both times it was when the batteries hit the low end of operational limits. In those cases, he was able to switch to a backup mode that kept 10 percent of battery capacity in reserve.

The biggest advantage to lithium-ion? “They recharge significantly faster than conventional batteries,” Jones said. “There are only small losses when transferring the electricity generated into storage. This allows us to use a smaller house bank and get the same results.”

But at $1,300 a pop for each of Aqua Vida’s three new 75-Ah batteries, the initial cost was significantly higher than for more conventional options. If Jones’ math proves to be correct, however, the new lithium-ion batteries are an investment that will last three to four times as long as his old 4Ds.

A step further
Keith Underdown has gone a step further. Not only is Cat Ion, his 44-foot PDQ Antares catamaran, equipped with Li-ion batteries, but his 48-volt battery banks are the hub of a diesel-electric propulsion system that was built into the boat when it was laid up in 2007.

Underdown’s brother, Ian, an electrical engineer working in the field of battery technology, was the first owner of Cat Ion and the mastermind behind its unique power system. “By replacing the inboard diesels, we were still constrained by the boat’s engine design weight,” Underdown noted. Lead-acid and AGM were simply too heavy. “Lithium batteries provide a much higher power density, and can be much more rapidly replenished by a DC generator,” he said.

Running on the batteries only, Underdown’s range on dual Whisper Drive electric motors is only about an hour. But, with the diesel generator replenishing the batteries, he can go as long as his diesel fuel holds out.

Cat Ion is on her second set of Li-ions. The first generation, installed at the yard, was when the technology was “in its infancy, and relatively expensive,” Underdown acknowledged. Seven years later, he put in “improved and evolved” lithium iron phosphate (LiFePO4) batteries supplied, like Ken Jones’, by Lithionics. Although by then the price had come down, it was still a hefty $15,000 to repower the 20-kW bank. Underdown, however, was pleased with the results. “At anchor … [we] can run microwaves, washing machines, watermakers, air conditioning, fridge and freezer, and depending on usage, we go for several days without needing a recharge.”

The workings of a lithium-ion battery while charging and discharging.

Safety concerns? 
Of course, it’s impossible to talk about Li-ion batteries without addressing the safety concerns — primarily the risk of fire, a problem that has gotten a lot of media attention. With the elaborate monitoring systems now available and the latest lithium iron phosphate technology, which is much more stable than the earlier chemistry, Tartaglia at Lithionics claims the company’s batteries are even safer than lead-acid.

He says the company has done “well into the hundreds” of installations on boats over the past seven years with a perfect safety record. In fact, Lithionics has worked closely in the past two years with the American Boat and Yacht Council (ABYC) to develop standards for the use of the high-tech batteries in boats.

Alan Olson, project manager for construction of the recently launched Matthew Turner, a San Francisco-based educational tall ship, started thinking about electric propulsion a decade ago when plans for the vessel were in their formative stages. At the time, lead-acid was the only viable option and the numbers for them, particularly considering the weight, just didn’t add up.

Li-ion proved to be the missing piece of the puzzle. “By the time we [were] ready to make a final decision two years ago, technology had changed with batteries,” Olson said.

After doing considerable research, Olson opted to go with BAE Systems, which enjoys a good reputation for installations on hybrid buses and trucks.

Olson acknowledged that “we had folks telling us it was not a good idea,” but ultimately, any safety concerns were allayed. Matthew Turner’s Corvus Li+ batteries supplied by BAE Systems are Lloyd’s of London compliant. The same installation has been approved by the Coast Guard for use in passenger vessels. Safety features include shutdown technology and a system for spraying water on hot batteries in the unlikely event of “runaway chemistry.”

With more interest in this technology, the price for cruisers seems likely to come down. It might not be long before they’re powering your boat.

Scott Neuman is freelance writer living aboard a Tayana 37 named Symbiosis

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