2010-08-250001-Hybrid propulsion system

Comment by boatsmith on August 30, 2010 at 5:27pm

Thanks for sharing Bertrand. I am very interested to see how your propulsion system works out. David

Comment by Chris Bretter on September 3, 2010 at 2:48pm

Very very interesting and well done on probably being the first hybrid driven wharram! How long will your batteries last before needing charging? Regards Chris and Noreen

Comment by Bertrand FERCOT on September 9, 2010 at 3:56pm

Chris, I'm not the first hybrid driven Wharram because the Jeff's Tiki 46 "KittyWake" has 2 "Re-Epower" electric pods bolted under each hull in front of the skegs which seems not enough powerful for a such cat and the Tiki46 "Apatiki" of our Belgium friends who has so 2 pods bolted under their hulls with a better power of 10kw each. They have serial hybrid systems with a diesel-generator to maintain the battery bank.
It seems I'll be the first to have a twin parallel hybrid system. The big difference is the diesel engines are able to drive directly the propeller to supply and electric or electronic failure or to give more power during a long time if necessary.
More you draw current from the battery bank, lower become the initial capacity of the battery : a nominal battery capacity of 200A/h (calculated for a discharge time of 20h or current of 10A) will become only about 100A/h if you draw a current of 200A . So if I motor at full throttle : 10kw or 200A under 48V I could expect an autonomy of only 30minutes, but if I motor at 4.5kts on smooth sea with no wind, I'll need only 1kw or 20A on each engine during about 7 hours to don't discharge completely the battery bank or 1kw at 3kts on one engine in drawing the 2 battery banks (which are in parallel) during 15 hours to don't empty the battery banks.
Only to manoeuvre when arriving or leaving an anchoring the battery banks are enough without the need of the diesels.
When I'll have more time I'll show graphs indicating the power and the drag of a Tiki46 according if the sea is smooth or rough and according the boat speed .

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