Low Voltage

Experts say battery technology must improve for electric boats to become a viable alternative to gas or diesel
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Torqeedo’s Deep Blue outboards are among the most powerful electric motors available.

Torqeedo’s Deep Blue outboards are among the most powerful electric motors available.

Steve Trkla is the president and general manager of Torqeedo, arguably the best-known name in electric propulsion systems for boats. He manages North American operations for the company, which has its headquarters in Germany. Trkla has a pretty big stake in seeing electrically powered boats become more popular, especially in the United States.

Yet despite the longstanding hope that technology for electric boats would be much farther along by now, most experts say batteries haven’t advanced as fast as once predicted. “I started writing 10 years ago that we would have a vibrant market by now,” says Nigel Calder, president of Calder Marine Enterprises and an expert on marine electrical systems. “Once you put the engine into the picture, the possible permutations get to be pretty high, and optimizing the system becomes more complex.”

Years ago, Mercury did a hybrid propulsion system with a diesel engine and a sterndrive. “Here’s why it hasn’t come to market yet,” says John Pfeifer, president of Mercury Marine. “It’s battery technology. We could do a Tesla-like propulsion system, and if you took that same system and put it in a small boat, it would last about 10 minutes.”

On the website spectra.mhi.com, Paul Lee says he does not expect change anytime soon. Lee is the head of technology, media and telecommunications research at Deloitte, a muiltinational professional services network. “Over the next five years, lithium-ion is likely to remain the basis of almost all batteries used in smartphones,” he told The Financial Times. “At present there appear to be no battery technologies on the horizon that have evolved sufficiently to be tested and factored into supply chains that could displace lithium-ion.”

Peter Haffenberg is the CEO of Oceanvolt USA, Tor­qeedo’s primary competitor in the electric propulsion arena. He agrees that alternatives to lithium-ion are at least five years out. “Other chemistry batteries are not really mainstream enough to be cost effective,” he says.

Current Applications

The primary challenge in the marine sphere is the amount of power it takes to get a boat on plane. Electric motors are known for producing loads of torque, but the initial power required to get the boat up and moving can tax a battery system. That’s why pontoon boats and non-planing commercial vessels have been among the most successful applications — they don’t need a big initial surge to get moving.

Trkla owns a 22-foot Apex Marine pontoon powered by a Torqeedo Deep Blue outboard with two Johnson Controls battery banks. He spends weekends on the Chain O’ Lakes in Illinois and has mastered dayboating with electrical power. “I’ve been doing it now for three years,” he says. “Top speed is 19 mph. But I also get range. I can do the complete loop on the chain, six hours out of the day.”

Torqeedo works with 18 pontoon builders, Trkla says, matching the right power systems to the right hulls. “If you’re going to do destination boating, you need to go to our hybrid system,” Trkla says of the company’s diesel generator-electric motor package. “We are the first to complete a full hybrid system that’s all Torqeedo.”

Oceanvolt builds full-electric and hybrid-diesel systems. The company’s sailboat systems have the option to regenerate power to the battery bank while under sail. Oceanvolt’s systems are optimized to run at 48 volts. Haffenberg says solar-cell efficiency is improving and that in applications such as large catamarans, solar can be a “reasonably good source of power for battery recharging. Eventually, solar cells integrated into the deck or sails may become mainstream.”

Volvo Penta’s hybrid system combines diesel and electric power with its IPS pod drives.

Volvo Penta’s hybrid system combines diesel and electric power with its IPS pod drives.

The most successful hybrid-power user in recreational boats is Greenline, which builds diesel-electric hybrids. Calder says the key to Greenline’s continuity has been a fairly simple system that allows the operator to decide when to use the diesel and electric operating modes. The company has also used solar panels on a pilothouse roof; in bright sunshine, solar power kept the boat running at 4 knots.

On the commercial front, Torqeedo electric outboards power water taxis that run on San Antonio’s Riverwalk and in Oklahoma.

Torqeedo parent company Deutz and Torqeedo engineers collaborated on full electric and diesel-electric hybrid power systems under the E-Deutz name. E-Deutz is based on a modular electrification system that lets customers choose a combination of conventional and electric drive components for an application.

The company’s hybrid drive consists of a diesel engine and an electric motor with a battery pack. Deutz first demonstrated the system on two forklifts that would normally be powered by a 74-kW Deutz TCD 3.6 diesel engine. One had a hybrid with a 56-kW Duetz diesel paired with a 48-volt, 20-kW electric motor to provide the total 76 kW. The two power sources were linked with a transmission that let the diesel engine disconnect from the electric motor if necessary and run solely on the diesel. The full electric setup used a 360-volt system with the forklift’s diesel replaced by a 60-kW electric motor powered by a 30.5-kW battery.

Battery weight remains a challenge. The two Johnson batteries in Trkla’s boat weigh 330 pounds each. Tor­qeedo is working with BMW to marinize the automaker’s i3 and i8 batteries. They are the current state of the art. A single i3 produces 30 kW and weighs about 500 pounds. It replaces the twin JCI systems that produce 12.5 kW each.

Tow Sports

One segment where electric power could work is towboats. Correct Craft has developed several electric models that tow slalom skiers, which require speeds of at least 25 mph. And the company partnered with Torqeedo in Correct Craft’s Watershed Innovations project to build an ultra-quiet aluminum fishing boat with electric propulsion.

Bill Yeargin, president and CEO of Correct Craft, says a tow-sports boat would need about 150 kW for surfing and boarding. “If you like to wake up early and start off your day [surfing or boarding] or maybe get in a run after you get home from work, electric can be a great option,” Yeargin says. “Physics is working against you for all-day use because the hull surface creates a lot of drag, especially in a water-sports boat.”

Torqeedo’s Ultralight electric outboards are popular with kayakers, anglers in particular, and have a solar charging system and GPS-based, on-board computer that monitors range.

Trkla says Torqeedo has identified areas around the United States where there are a growing number of electric-only lakes, including outside Atlanta and in Connecticut. “There is a market of baby boomers with money on a lake who want a pontoon but don’t want to haul jerry cans,” he says.

The cost for a full electric propulsion system remains somewhat prohibitive, as well. An 80-hp Torqeedo Deep Blue outboard with the connection box and a battery costs about $50,000. That’s a big price tag on a pontoon boat. “The price isn’t going down, but the cells and the energy are increasing,” Trkla says. “People wonder when the costs of these batteries will finally come down, and the argument is probably five years because we haven’t maxed out the technology in these batteries.”

Haffenberg says daysailing is an activity where electric power can work well because the propulsion system is primarily a backup. He says hybrids are better for cruising and says that Oceanvolt hybrids with diesel generators can be used to power small passenger ferries.

A Commitment to Electric

Volvo Penta announced last summer that it was developing a hybrid diesel-electric IPS system that will be launched in 2022. “A hybrid provides a flexible solution, one with the high efficiency of the IPS system and the ability to run in zero-emission environments,” says Niklas Thulin, Volvo Penta’s director of electromobility.  The hybrid system is planned initially for the 8- to 13-liter Volvo engine range for yachts, ferries, and pilot and supply boats.

Thulin says the system has a new clutch and electric motor added between the engine and IPS pod. The electric motor is supported by scalable (depending on application needs) Li-ion battery packs that can be charged externally using AC or DC chargers, or recharged using the primary diesel. The clutch allows the boat to run in electric-only mode, and with the clutch closed, diesel and electric power can be used simultaneously.

Torqeedo’s primary competitor is Oceanvolt, which makes complete electric propulsion systems.

Torqeedo’s primary competitor is Oceanvolt, which makes complete electric propulsion systems.

Volvo began experimenting with electric about five years ago and studied the types of boats where it would make most sense. “The hard part wasn’t about putting an electric motor on the IPS,” says Hanna Ljungqvist, vice president of new business at Volvo Penta. “The hard part was determining how it would be used. It might make sense for towboat applications, where you use the boat for an hour and go back to shore. It was more challenging for boats running eight hours at all speeds.”

The company decided to mate its first electric motor with an IPS because the diesel engines could provide an unlimited supply of power with diesel fuel, and the hulls that use IPS are large enough to carry several battery packs without significantly compromising performance. Thulin expects to see more electric installations on boats over the next five years, with lithium-ion batteries remaining the best option.

Torqeedo’s Deep Blue battery is derived from a BMW automotive unit.

Torqeedo’s Deep Blue battery is derived from a BMW automotive unit.

Get the Lead Out

While the wait continues for lithium-ion battery technology to improve, Calder says advances are being made in lead-acid batteries. Ocean Planet Energy manufactures lead-acid batteries under the Firefly brand. They were developed as a special project for Caterpillar tractors and have a patented microcellular carbon-foam plate structure that has more surface area than traditional plates. The foam is sliced super thin and coated with lead.

More plates in the same size housing means more stored energy. Firefly batteries charge faster and can be discharged faster and more deeply. Each comes in a Group 31 size that weighs 75 pounds. Lithium-ion is lighter and gives more amp hours out of the same space, but pricing for the lead-acid battery starts at $512.

Firefly’s Oasis batteries feature carbon-foam plates that provide more power in the same size case.

Firefly’s Oasis batteries feature carbon-foam plates that provide more power in the same size case.

Yeargin is certain that batteries will advance to the point that electric boats will be a viable option in the near future. The company is so confident that it acquired Ingenity P220, an electric boat-drive system developed in Austria. “The acquisition will help position Pleasurecraft Engine Group and our boat companies for a successful transition to the future,” he says.

The Correct Craft CEO is bullish on electric boats. “You no longer have to worry about fuel, and there are 90 percent fewer moving parts versus a combustion engine,” he says. “With the amount of money being invested and the number of smart people working on electric, the technology will never perform worse or cost more than it does today.”

Calder is a bit hesitant in his assessment. “The one thing that hasn’t really changed is how much power it takes to move a boat,” he says.

This article originally appeared in the February 2019 issue.