High power alternator, an ultra-quiet dehumidifier and a dry bag tested
Generating sufficient electrical power for use on board has been a perennial problem. In some ways it has become easier with the steep drop in the price of solar, but at the same time our boats have become more complex and we also have to power devices such as smartphones, tablets or laptops.
Both conventional engine mounted alternators and separate generators are enormously inefficient – potentially costing an incredible £5-20 per kilowatt hour once depreciation of the hardware is factored in. At the same time, diesel propulsion engines tend to operate at relatively low revs – a very inefficient area of their power curve.
These two factors mean there’s potential to deliver a significant charging load from the main engine without impacting propulsion performance. At the same time overall efficiency is improved. This is the basis of the Integrel system developed by Cornwall-based Triskel
Marine, which is intended as a replacement for stand-alone generators. “It exploits the fact that the engine would like to provide more power at given revs than the propeller takes,” explains managing director Ken Wittamore. The core of the system is a 9kW high-output 48V alternator fitted in the normal position for a second alternator on a boat’s engine. The raw output from this goes to an external regulator that incorporates a rectifier to convert the three-phase alternator output to 48V DC. This then fed to a 10kW battery bank specified for a ten-year design life. Software regulates the charging output, optimizing output for two distinct conditions – underway and generating at anchor. The charge characteristics are adjusted for each engine model and it automatically scales down charging load at low engine speeds and when peak engine revs are selected and all the engine’s power is therefore needed for propulsion. A significant amount of testing has taken place, including in a fleet of charter cats, while yachting journalist Nigel Calder was engaged to attempt to ‘break’ the system. Although testing has been on Volvo Penta and Yanmar engines, predominately in the 50-70hp range, Wittamore says it’s suitable for use with engines as small as 30hp.
It’s worth noting that this system is hugely more efficient than the engine mounted AC 240V alternators that have long been popular for use on inland waterways. The Integrel is the result of ten years’ research and represents a step change in efficiency, with the electricity generated some 5-10 times more economic than from other diesel fuelled methods. Up-front costs are similar to those of a stand-alone generator, but long-term operating costs are much reduced, while reliability and convenience are better.