Basic goal of diesel genset is to provide enough continuous power to run at 6 knots. That's 85% hull speed.
When I was still conceiving my system I estimated it would take 7200 watts for 6 knots. I purchase a Kubota 722 3cyl engine rated at 12kW (16HP) @ 2200RPM and a 12kW ME1616 motor that is rated at .026V/rpm as a 3 phase generator (if I am interpreting that rating correctly). Charging voltage would be about 57 volts so that's 2192 RPM. A very good match. Output from this BLDC generator could be in the 95% efficiency range as I understand it. So I should be able to get 10kW from this setup accounting for losses from rectifier and regulator.
After building my electric drive I found it to be more efficient than predicted and I can make 6 knots at about 5000 Watts. So perhaps I could get 6 knots with a 6kW generator rather than 10. But it would be running at close to 100% to do that. I would rather be able to back off a bit to 65 or 70% where the diesel will still be happy but I have some headroom. So my 10kW unit still makes sense.
In general I think the entire electric drive system should be designed so you don't need to run at 100% to get the speed you need. And you need to be realistic about that speed. Loafing along at 3 knots is not practical unless all you need is daysailing from a protected small boat harbor with no real current or ship traffic to deal with.
So far I have about $3300 in the components for my genset. I don't expect it would go much past $5000 total and I should be good for 10kW? I have more research to do for that and I need to source a rectifier and regulator and fabricate a cooling system.
Dan Pfeiffer
What are your 48VDC generator goals? KW? Marine diesel HP? I have fooled around trying to do the same with a spotty record of success.
I have found a company doing a 200A/48VDC (10kW) with a snazzy iPad app to control LFP charging. Quoted 8,000 Euros. Much better price than the Fischer Panda 11kW 48vdc unit. ._,_._,
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