Making a high efficency 3 Kw DC Generator

Discussion in 'DIY Marinizing' started by kistinie, Mar 8, 2009.

  1. apex1

    apex1 Guest

    That does´nt work, except you carry a sufficient amount of sweetwater in your tanks. Saltwater destroys your injector and manifold in no time.

    And... we are not at a prop subject, but at a prop driven genny. You really should take some time to read what people reply on your posts.

    And.. NO, I do´nt like to be more precise, that subject was handled here and elsewhere almost to death. I´s not worth to go in deep. And links I do´nt like to provide anymore at your threads, you do´nt use them anyway.
  2. kistinie
    Joined: Aug 2007
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    kistinie Hybrid corsair

    is it your opinion or experience ?
    if experience with what equipement
    size, brand, debit, type of pump ???

    if opinion, can you explain how you went to this conclusion ?

    No, here generator is not prop driven, electric motor does this already ! i use fuel for running a generator you should be happy...Please it is already difficult enough for me to accept the idea of a petrol generator, do not hurt me more !

    Yes love you too dear Richard
  3. apex1

    apex1 Guest

    What am I doing here? I´m mad.


  4. masalai
    Joined: Oct 2007
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    masalai masalai

    kistinie, I like the diesel generator idea and is an example based on a 3 cylinder 719cc Kubota Diesel Engine... Sadly is not made now? but the Polar Power generator is very efficient, brushless and configurable.... Most brushless electric motors require a sophisticated pulse mode controller to operate at the efficiencies you talk about as energy losses of pure DC and otherwise control is probably somewhat problematical.... I am looking at developments in the Torqeedo leg from Germany/Europe???? 2000 & 4000 w options in the cruise R range using 24 and 48v respectively and co-gen coming soon...
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  5. Ilan Voyager
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    Ilan Voyager Senior Member

    Why to go to a so complicated scheme for 3 Kw? when a simple 5 HP outboard 4 S will do the job? Gosh, the old engineer I am scratches his head. Ok on a big ship where a few % saved on thousands of Kw are significant, balanced to the cost of investment. The true price of your hybrid is far higher that you think...add the cost of an heavier boat, and all that needed for a real working hybrid.
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  6. kistinie
    Joined: Aug 2007
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    kistinie Hybrid corsair

    I used to have a yanmar 1gm+sd20 inside
    Don't want it any more
    same for outbord

    Electric choice is done.
    Price is low, in my budget.
    No problemo.
    Do not worry, i really beleive in my study.

    Now i miss the 3 kw dc electric generator, air cooled, very efficient, light ...


    yes nice choice, but 3 certainly expensive...very good result for 98 Kg.
    But to big for me
    Need half size of this, even if just 2.5 Kw
    50kg is the max, also a question of available space, that i do not have
    Cheers !
  7. apex1

    apex1 Guest

    Francois, you are not to cure.
    You know already the price is low! But naturally you do´nt know if your sort of genny does exist, let alone the cost. Thats pure entertainment.:p
    I know such generator, as I know the price, naturally. No, no further links for you. Find it out the hard way.
    I´ll ask for your solutions, once I encounter a serious problem.:D
  8. kistinie
    Joined: Aug 2007
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    kistinie Hybrid corsair


    You are welcome !

    Richard ! You are my entertainment !
    You are pure gold. The cream of humanity.
    You are perfect !

    Don't change a thing !
  9. alan white
    Joined: Mar 2007
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    alan white Senior Member

    "Glad you like regeneration, make really sense on fast light sailing boats
    We can even do much better than hybrid sailing boat

    Outboard is on the side on 2 rails close to rudder. Works only when water flat
    150 kg of lead is less than on hour high speed, but i think 6 low speed as i am very efficient with very small wet area, and very narrow, therefore drag is not linear
    how do you get heat out of the box for generator ?
    A radiator to salt water inside box ?

    i already have two yanmar IGM and no
    Too big for me
    Too heavy close to 60 kg.

    i will use the generator once a month i guess, not more"

    I see. Well, you are in the same predicament as anyone who installs an inboard engine. Raw water or fresh, simple or more complicated. A cast iron engine block can last for twenty years in salt water, especially if not used too often. I guess I'd go that route, just a raw water pump run off the engine. You might look for a rebuildable Vire Danish 7 hp 2 stroke, which is light and usually raw water cooled, with a built-in pump. They run on kerosene when warmed up. Very reliable and simple but not clean running or efficient. But if you're getting most power from the prop, it shouldn't be a big problem. Or maybe there are some water cooled engines out there in that size range.
  10. alan white
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    alan white Senior Member

    I assume it would be possible to modify an outboard motor to accept an electric motor generator (a controller is required). Then the prop only delivers power when wind is strong. Otherwise, the unit is raised. Again, however, 150 kilos of battery bank will yield no more than a couple of hours of low speed (4 kts?) cruising before the genny has to run. A feathering prop on the hull won't work as a generator, and it's true the prop is a drag.
    I'd think a wind generator is the way to go.
  11. pistnbroke
    Joined: Jan 2009
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    pistnbroke I try

    You cannot charge you batteries at more than 25 A or they get very hot and and gas 4 x12v (48v) have an on charge voltage of just under 60v so thats 1500 watts at 25A charge rate ..which of course will fall as they approach full charge thats halved the cost of your project !!!

    If you bought a 120v 1250w generator the 120v would be tapped at the centre giving 60v/60v Two large diodes and you have 60v at 20a for your charger ........adjust gen speed to regulate output volts ....yes/no ???
  12. Frosty

    Frosty Previous Member

    A freind of mine spent 1 year on the hard converting his 54 foot cat with electric Vetus motors with controllers and chargers etc. It was nothing less than a disaster, gutless waste of time. He could not move the boat longer than 6 hours even with the 6KW generator as the chargers could not keep up with demand.

    What would have been wrong with two deisel motors.?

    It had 8 batteries per side with 4 chargers a generator etc etc. How heavy is all that?

    The enormous feed cables must have weight 100 kilo.

    The boat has been for sale 2 years now and I personally look after this boat and show them around,-- no one has made an offer to date.
  13. Landlubber
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    Landlubber Senior Member

    Teddy Diver,

    Continuous, in the context described, is not continuous, it means that it can actually put out that much when running.

    That sort of gen set has no hope of survival if actually ran continuously.
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  14. kistinie
    Joined: Aug 2007
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    kistinie Hybrid corsair

    Until i find a light air cooled 48V DC genny, 2/3 Kw, weighting less than 40 kg

    i still have this inexpensive and very very reliable solution

    Direct drive, belt reduction
    i think i can direct drive the electric motor propeller shaft with a folding honda 6cv motor.

    Only forward will be available on honda motor propulsion
    Reverse with electricity only.
    exhaust will be water injected, with full hastelloy tubing

    Cannot do a simpler and safer solution ?

    Yes !

    This one of course, that will be aboard too
    it was my first engine when a started sailing on "mousquetaire" in the 80's
    quite powerful on a boat like mine and my 300 or 400 watts i guess

    Human power !

    Attached Files:

  15. kistinie
    Joined: Aug 2007
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    kistinie Hybrid corsair

    Rather yes Pistnbroke yes !

    The idea smells very good !

    How do you tap the centre point on the alternator, is it usually easy to access ?

    Only drawback will be the poor regulation and having 2 battery groups to use the 2 out + and - with the danger to have 120 dc in-between ?
    or use only half of the alternator, but in this case i may burn it with over amps ?
    a serial inductance can help filtering, and in case of lead batteries, this is not tragic.
    has someone tried this ?
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