Boating NZ : FREE TO READ March 2014
technology will argue that a straight amp-hour-for-amp-hour comparison is not fair – you need to factor the batteries’ entire life cycle into the equation; ie, longevity, less frequent replacements, fuel savings and zero maintenance. Do the sums and the extra cost is quickly absorbed. There’s a secondary expense. Every lithium-iron installation is, or should be, equipped with a sophisticated Battery Management System (BMS). A crucial part of the technology, it balances the voltage across the individual cells. To avoid battery damage, the BMS controls how much current comes in and limits what goes out. It prevents the battery’s voltage falling below the 80 – 85% discharge threshold. Finally, few lithium-iron battery retailers will recommend the installation as a DIY job. You’ll need some specialist expertise and will probably have to pay for it. If you’re still undecided after weighing up all the pros and cons, the equation definitely takes on a different complexion when you consider the possibility of using the batteries to drive your boat. ELECTRIC PROPULSION Using batteries and electric motors for propulsion isn’t a new concept – W W II submarines did it all the time – but it’s difficult for recreational boats because of limited storage. The weight/size of the appropriate battery bank/charging system would probably sink the boat. Lithium-iron technology changes this. John McGettigan is managing director of NewPowr in Auckland, the Australasian agent for lithium-iron batteries manufactured by China’s Hi-Power. McGettigan has equipped several boats with lithium-iron systems, but is particularly keen on using the technology for propulsion. To prove its viability he recently completed the 120-mile Auckland- Paihia passage in a boat equipped with a 200 amp-hour bank of lithium-iron batteries, what he calls a proof-of-concept voyage. The vessel, E-Gen, is a Kevin Dibley- designed, 27-foot picnic boat. Built in fibreglass, she weighs about 950kg. Before her electric conversion, she was driven by a 20hp Honda outboard. Her new 48-volt system comprises two lithium-iron battery banks installed under the seats up front. Each pack measures 320mm by 210mm by 270mm (LxWxH). Combined, the batteries weigh 110kg. A Sonic stern leg bolted to the transom is driven by a permanent magnet, brushed, Lynch motor mounted inside, in the lazarette. Rated at 18kW continuous power The 18kW electric motor drives a Sonic stern leg. Where conventional batteries have individual cells integrated into one case, lithium-iron batteries have individual cells of 3.2V each, strapped together and connected in series. The cells are typically grouped for the three common ranges used in recreational boating – 12V, 24V and 48V – and can be scaled to any amp-hour size. An advantage of this system is that if one cell fails you replace only that cell – not the entire battery. A soft cell 0314-290113303123 Locations: • 5G Miro Place, Albany, Auckland • Gulf Harbour Marina, Whangaparaoa, Auckland www.enertecmarinesystems.com email: firstname.lastname@example.org your li ion battery specialists over 5 years installation experience 0314-80 60 Boating New Zealand March 2014 PBoating_Batteries_March14.indd 60 19/02/2014 10:06:59 a.m.
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