New Gear

Practical Boat Owner - - Contents -

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.

■ in­te­grel­ma­

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