Making a high efficency 3 Kw DC Generator

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

  1. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    See I am not as stupid as that rep of 3 would have you think...

    As to the centre tap ..if its 120v the "earth pin" is the centre tap hence 60v on each output pin relative to the earth pin ...( Yanks are usefull sometimes)
    A series or parallel regulator would get very hot but a pulsed regulator like in a dimmer would work ok using two SCRs or MOSFETS
     
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  2. kistinie
    Joined: Aug 2007
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    Location: france

    kistinie Hybrid corsair

    We always need someone at the other side of earth !
    I will try do dig this a little more

    For regulation i can use a a peak suppressor regulator (just like on wind mills) sending extra volts to a resistor
    When it gets hot, does a bip and i cut
    But as motor will be turning and the battery flat...it will be very long.
     
  3. apex1

    apex1 Guest

    Alan
    what Kistinie wanted was´nt a raw water cooling of the engine! He wanted a water injection into the exhaust manifold where the water vaporizes immediately. That does function with gas engines and destilled water (at a high price to pay for proper engineering and installation). But it definetily does not function with saltwater and Diesel engines. The injected water would build up salt, soot and acids in no time throughout the exhaust duct. Not to mention further disadvantages.
    But that´s all not the problem, just playing with unmature ideas.
    The problem is energy storage. And neither Kistinie, nor anyone else has a solution for that. period
    So all the nice thoughts are worth nothing until we have solved that first!
    A Diesel engine cannot be subsituted on a seagoing vessel at a reasonable (that is maximum twice the standard installation) price. period again
    We all have to love it or leave it.
    Regards
    Richard
     
  4. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    I personally think electric boats are a big mistake unless your a cruise ship or a Navy and need the extra electricity for something.

    BUt anyway, to build a low cost Diesel DC generator.
    Get a Lawn tractor diesel about 20hp (there are several brands)and hookup two 200 amp alternators from something like a Ford F250 Diesel tractor . Expect motor to run at full power to take load when being used.

    You can get lawn tractor engine for about $500, they are water cooled and you can hookup keel cooler. Forget about aircooled, any diesel running at full power trying to generate 400 amp is going to make a bit of heat.

    I thought of making one of the run the hydraulics. Instead I am going with Deutz which oil/air cooled. I didn't mention it as a way to go because they are expensive motors.

    Everyone wants DC because it is cheaper and easier to throttle motors, however if you look at most good system like Siemens, or hybrid cars, they use AC. AC is much more efficient than DC, the problem is cost of control units. If I want to make a hybrid boat, I would find a crashed hybrid car.
    DC vs AC is the difference between Golf Cart and hybrid car.

    Suggestions for all electic boaters. Buy the engines with a 30 day money back, install, get batteries and take a short trip around bay. When the performance is not what you want then you can return the very expensive motor without buying the rest of the stuff... Otherwise be prepared to have a Nasa budget to make it work and the performance will be less than simple gas or diesel motor....
     
  5. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    I do agree about the storage problem, which I've brought up several times.
    Especially on a light boat, where batteries weigh enough to seriously affect performance.
    I believe hybrid cars are viable because they pass through air and not water, but boats require a lot of constant energy to pass through something as viscous as water. I do agree that some boats can benefit from the use of an electric motor in order to relocate the diesel, to run the diesel at optimum RPM, and to avoid the power-robbing transmission.
    However it may appear at first glance to be a "hybrid" sytem, such a setup is better termed an electric drive---- and even the weight of batteries is not a problem because such a system can work direct generator to motor.
    However, in pleasure boats, as I said earlier, a system involving both diesel and electric components is an expensive setup.
    In a work boat, initial outlay of capital is hopefully oiffset by daily savings, but a pleasure boat isn't used that way. Small or even moderate savings in fuel, in other words, never offset initial cost of building the system.
    I think under the right circumstances, an electric DRIVE (not hybrid) makes sense on a sailboat. This would be where only a medium/small battery bank was required, and where the prop could be used to generate electricity at times while under way.
    Such a system would allow the diesel generator to be relocated (to typical vee drive location, mid-boat or even forward of that). It would eliminate the transmission and its attendant friction losses. In addition, a moderately small battery bank could allow silent operation for short periods, and emergency maneuvering when the diesel wouldn't start.
    With more batteries, the advantage becomes running the diesel at constant RPM, but in such a case, the batteries are acting as, and eliminating regular ballasting.
    The most efficient drive for a multihull, considering initial cost, operation over time, and performance-wise, would be something like a high-thrust outboard with remote controls and a power lift. A ten hp unit from Yamaha might cost $2500 US, and it would run very quietly on gasoline. It would weigh about 125 lbs with all gear. I don't see how any other system could compete for price and efficiency if the unit is only an auxilliary, used only occasionally.
     
  6. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    I do agree about the storage problem, which I've brought up several times.
    Especially on a light boat, where batteries weigh enough to seriously affect performance.
    I believe hybrid cars are viable because they pass through air and not water, but boats require a lot of constant energy to pass through something as viscous as water. I do agree that some boats can benefit from the use of an electric motor in order to relocate the diesel, to run the diesel at optimum RPM, and to avoid the power-robbing transmission.
    However it may appear at first glance to be a "hybrid" sytem, such a setup is better termed an electric drive---- and even the weight of batteries is not a problem because such a system can work direct generator to motor.
    However, in pleasure boats, as I said earlier, a system involving both diesel and electric components is an expensive setup.
    In a work boat, initial outlay of capital is hopefully oiffset by daily savings, but a pleasure boat isn't used that way. Small or even moderate savings in fuel, in other words, never offset initial cost of building the system.
    I think under the right circumstances, an electric DRIVE (not hybrid) makes sense on a sailboat. This would be where no battery bank was required, and where the prop could be used to generate electricity at times while under way.
    Such a system would allow the diesel generator to be relocated (to typical vee drive location, mid-boat or even forward of that). It would eliminate the transmission and its attendant friction losses. In addition, a moderately small battery bank could allow silent operation for short periods, and emergency maneuvering when the diesel wouldn't start.
    With more batteries, the advantage becomes running the diesel at constant RPM, but in such a case, the batteries are acting as, and eliminating regular ballasting.
    The most efficient drive for a multihull, considering initial cost, operation over time, and performance-wise, would be something like a high-thrust outboard with remote controls and a power lift. A ten hp unit from Yamaha might cost $2500 US, and it would run very quietly on gasoline. It would weigh about 125 lbs with all gear. I don't see how any other system could compete for price and efficiency if the unit is only an auxilliary, used only occasionally.
     
  7. apex1

    apex1 Guest

    Alan I hope you do´nt mind the way I answered.
    Regards
    Richard
     
  8. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    In the final analysis, the outboard appears toi be the best overall solution for the boat in question, whether or not it fits the needs of any one particular sailor (with respect to kistanie's personal requirements, which need not be similar to mine).
    A multi weighing 2 tons need only have about 6 hp as said. An inboard minimum diesel would be heavier than an outboard, and much much more money. The outboard, if 6 hp, might weigh about 35 kilos. To haul around a diersel/electric system for non-sail propulsion in a multi would not be good for general performance, even if the weight is only 150 kilos. Weight is obviously extremely important to multihull sailing.
    Electric generation is always a problem if you have an outboard due to the small amperage output. In a case like that an inboard (small diesel) might be warranted despite the weight penalty---- you must give up something to get something, especially where weight is concerned.
     
  9. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Small CPPs are pretty hard to come by on our side of the pond, Richard, and when you do find one over here the price tag is astronomical. I don't have the slightest clue why this is the case.

    For a small DC generator to charge the house bank at anchor, I think the earlier suggestion of a lawn tractor engine with a couple of chunky alternators is a hard one to beat.

    For propulsion, I've said it on other threads and I'll say it again here- diesel/electric drive, in a boat, only makes sense if the house loads and the propulsion loads are of comparable magnitude. (See "cruise ship".) In most pleasure craft, the house loads are smaller than the propulsion loads- often by one or two orders of magnitude. Diesel/electric just isn't economical under these conditions.

    The idea of a transmission with 10-20% loss comes from old car automatics with non-lockup torque converters- a manual, or a marine gear, uses all-mechanical torque coupling and only wastes a few percent of the power.
     
  10. apex1

    apex1 Guest

    Alan
    I agree. But we are not talking about any sensefull propulsion here, we are talking about a dream of the replacement of a proven, reliable, efficient Diesel / prop drive. And installing a heavier, unreliable, unefficient, uneconomical electro propulsion, that will cost twice the price of the former. I know Kistinie dreams about saving weight, less noise, and a sort of "green sailing". Unfortunately, real world data prove, that will remain a dream at present.
    You know, I see all the advantages of a Diesel El. system, and you know I did play with some pretty sophisticated systems for my own yacht. But even I came (with all my background and all my capabilities and wholesale prices) to the conclusion to stay with a Diesel and a CPP, for optimal load of engine, economy, reliability and efficiency.

    So, to conclude: any kind of electro propulsion as known by today is heavier, less reliable, less efficient, much more expensive, than any IC eng. driven powertrain of either sort in- or outboard. period

    And then there was another phantasy of our French engineer, Manpower (he posted a funny picture with some funny calculations), one page back.
    Unfortunately this as well was ruled by optimism only. Human power output is in the range of just 150W cont. IF one is trained on the way to deliver that.
    Engineering dreams can be a joyful experience, and the world would´nt know the wheel if there was no dreamer in the past, but I see a difference between playing with some broad spread ideas and some sort of serious discussion about propulsion systems. All of Kistinies posts, threads and comments, by now, belonged to the former category exclusively.
    Further comment dispensable...............


    Matt
    you´ve got ten points for that! where to send the T-shirt?

    Regards
    Richard
     
  11. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    I paid $500 for a 4 stroke 5 hp Nissan engine less than a year old and $500 for 15hp 2 stroke, including a aluminum 14 foot boat. So it is not just new cost but market price engines that affect benefits. Cost can be even lower than new but on electric that is not an option most of the time.
     
  12. Frosty

    Frosty Previous Member

    Yes thats right, electric boats are crap. I wrote that on page # 27.
     
  13. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    I am moving my boat to highest concentration of electric boat and start charging for tows....

    Electric Motors are for windshield wipers.... That will get all you boiling hot.. lol..
     
  14. apex1

    apex1 Guest

    Nahh................ Skippers armchair, popup TV, tumble dry, macerator, spy cam, manoman, you obviously have just a tiny genny hähh?:D
     

  15. mudman
    Joined: Mar 2007
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    Location: Madisonville, LA

    mudman Junior Member

    I agree that electric power is just not possible without the assistance of a hydrocarbon fueled engine. Ships and trains use electric motors for the torque, but they run that off of a diesel engine.

    Yeah you could produce power through the electric motor at sail, but it's not enough. So the idea is to run this sailboat simmilar to a ship or a locomotive. OK Sure, but why?

    I built a camp recently and used 12 volt for lighting, so that I wouldn't hear a noisy generator. But when its hot out and I want air conditioning, I HAVE to run a generator. I could get 20 batteries and run an AC unit, but it would only be for a few hours (high amp draw like your DC motor). Recharging the batteries would take forever using wind or solar. Why would I get a generator to charge batteries for my AC? Why not run a generator directly to the AC unit. If I could figure out a way, I'd run an AC compressor directly off of a small engine. It's very simmilar to your boat and only makes sense.

    So why would you buy a 5 hp engine and alternator to charge batteries for your drive system? Why not put that 5 hp engine right on the drive shaft and bypass that extra step of ENERGY LOSS and extra weight? Cut out the middle man.

    It is much more efficient to run diesel or gas engine to run the boat. Getting the juice out of the battery is much easier than putting it back in. It takes about 5 times longer to charge a lead acid battery as it does to discharge (given the same Amp rate for charge and discharge).
     
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