Author: Roger McAfee
Lithium ion battery technology has been slowly, over the past couple of years, making its way into the marine market. Small, rechargeable lithium batteries were developed in the 1990s to power electronic calculators, watches and cellphones.
There are a number of properties of the lithium technology that make these batteries so attractive. The most important, especially for those used in cellphones, is they don’t acquire a memory. They can therefore be recharged from any state of charge without adversely affecting their capacity. The second helpful feature is that lithium ion batteries can be recharged very rapidly. A NiCad battery that used to power an early cellphone took almost four hours to charge. The lithium ion battery charging a new, similar cellphone, recharges in about 45 minutes. It also lasts almost three times longer.
The features for the smaller batteries — lack of a memory and high rate of charge — are much sought after in boating. There are, however, two other lithium battery features that are finding great favor with boat owners.
The first is relatively light weight. Lithium is one of the lightest elements in the periodic table that is not a gas. It floats on water, and a cubic foot of it weighs 62.4 pounds. By comparison, a cubic foot of lead tips the scales at about 710 pounds. A lithium-based battery of about 61 pounds will have approximately the same capacity as a lead-based battery of 168 pounds. This gives marine designers, builders and decorators much more flexibility.
The other feature mariners like about lithium technology is the fact that the batteries can be charged very rapidly without adverse effect. One builder of aluminum yachts reports that the lithium house battery system he installs requires only one hour of generator time a day to keep the house bank fully charged, compared with four hours for the more traditional lead-based house system he used to install. Other builders and refit yards report the same thing.
The improvements in lithium technology in the past two years have led to the development of a couple of all electric outboards. Torqeedo has produced an 80 hp unit, and a Canadian boat builder, Campion of Kelowna B.C., has produced an all-electric outboard of 180 hp, which (as of this writing) is the most powerful all-electric outboard in the world. Elco has just announced an all-electric outboard, as has i-Glide. The latter two are smaller outboards at the moment — less than 10 hp — but apparently they both have more powerful units on the way.
Last year, a mega-yacht builder announced the development of an all-electric 12-passenger shoreboat for running guests from the anchored mega-yacht to shore — at 45 knots. The shoreboat is to be powered by a pair of 300 hp all-electric outboards.
With the advent of all-electric outboards of meaningful horsepower, as opposed to trolling motors, and the success of the Tesla all-electric sports car, lithium battery manufacturers have had to up their game considerably, not only with respect to the amount of power that can be stored but also with respect to their battery management systems (BMS). In the short two years since the debut of Campion’s 180 hp unit, which required thousands of small cells to be hand “assembled” to produce the 400 VDC required to power the unit, Campion’s Florida consultant has begun manufacturing, in China, a 100-pound, 51v battery that stores 7.25 kw of power. The internal battery cells are fitted into in an almost traditional looking, dustproof and water-resistant case. Each battery has its own battery management system on board and is about 26 inches by 11 inches by 7 inches.
These types of batteries are still relatively expensive, but major developments in the electric auto field may soon start to flow into the marine field. In Europe, Renault produces an all-electric car, that is sold without the battery pack. The pack is leased by the car buyer for the equivalent of $100 per month. Gas was costing the buyer almost $300 per month, whereas the battery pack cost, including the battery lease and charging, is about $110 per month, and if there’s a battery problem, the builder supplies a new battery at no cost. The battery lease/rental business model for the marine field is currently being examined by a number of leasing companies.
There will be continued development in battery technology, but these batteries have now reached the point where they are viable for many marine uses. They are still a bit pricey, but when one considers they have about three times the life of regular lead-based batteries, the cost, over time, is not that much more.
Tesla started construction late last year on a $10 million lithium ion battery manufacturing plant in Nevada, and Panasonic, a major player in the LI battery business, will be involved with the car maker in that venture. As that factory comes online, look for LI battery prices to fall.