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Forum Index : Windmills : hydro f&p - how to wire?
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| shredder7753 Newbie  Joined: 06/01/2012 Location: United StatesPosts: 3 |
Hi All! im building a hydropowered f&p generator platform with 2 16"propellers each connected to an outboard motor lower unit(gear housing)which is connected to new 36 pole f&p's (got them from Randy B.). i havent modified the f&ps yet. Randy said that the f&p outputs 0.9 watts/rpm regardless of how it is wired. but TBSs wiring diagrams and associated wattage graphs tell a different story. im guessing the water current is maybe 1.5m/s. the props have a 17in pitch, and when the prop shaft is turned one full turn, the vertical drive its connected to gets turned 1.75 times - thus turning the f&p hub 1.75 turns for each rotation of the propeller. Doing some math, the theoretical rotation of the hub with NO prop slippage in the water is 7 rotations/sec or 425 rpm. i have no idea what kind of slippage the prop will have so lets say 20% with no load? thats 340rpm but with hydro powered torque, not wind torque. does anyone know how i should wire my f&ps for maximum power production? they're the 36 pole model 60s. im running a 12 volt circuit. how much wattage can i expect from each one? not to confuse the issue but this river is tidal. it flows in, then it stops and flows out, then it stops and flows in... 1.5m/s seems like about average because it does move pretty good at peak flow. After my test platform is complete i hope to install these 2 generator units to the bottom of a floating concrete island which has many small electrical components to run: http://seasteading.org/interact/forums/community/active-seas teading-projects/berg-3rd?page=5#comment-19380 Thanx! Rich Allen from DE |
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi Rich, Glad you could join us. We are only a small forum and most of the F&P enthusiasts are relaxing on summer holiday at the moment, so it may be a struggle to get someone to spare the time for a detailed answer to your power question. There are a lot of resources here if you can find them. from the projects page to something new and exiting from Steve and Bob Have a look at the video  I am sure these will answer a few questions and create more.
I fixed the link to your project, the forum text formatting added a space. It looks like the link may disappear soon, it would be great if you could post a couple of pics directly here, so the members can see what you are up to. bergstead floating platform Matching a generator load to the output power is the key, unless you know how much the prop can be loaded at different RPM before cavitation starts it is hard to imagine a power curve for this setup. I think turbulence will be a big factor in how the props perform, same as wind! Are You going to run them upstream from the leg? cheers yahoo I'm confused, no wait... maybe I'm not... |
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| shredder7753 Newbie Joined: 06/01/2012 Location: United StatesPosts: 3 |
i have been holding my breath ever since i posted that but no one answered till now. thank u for being thoughtful. im starting to think this might be an Aussie website, as its still winter time where i am (near Philadelphia). i dont even know how im gonna measure the available torque once the turbine platform is completed. it will be a challenge, it seems. i love the MPPT video! thats awesome.
so this is what my test platform for the generators will be like: 
heres a cut-thru image of my floating private island design. its called a "Bergstead". I want to make it possible for people to live autonomously outside of any existing nations legal territory. 
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
What you are building is called a free flow or kinetic reaction turbine. my guess is without a pipe wall to hold the water in and guide vanes to create a vortex, a lot of the kinetic energy will slip around the outer edge of a small prop and be lost. There is a lot that can be learned from larger commercial systems. this is a good example from the St Lawrence or East river NY, the prop speed here is 32 RPM but the gain is the water will flow smoothly over the blades with minimal cavitation and stalling creating huge amounts of torque. 
image:verdant power inc I wouldn't be to worried about wiring a generator for the peak flow in a semi tidal river the top end normally takes care of itself, as there is an exponential increase in energy available for every unit increase in speed. the points that are more important are the revs (and load) that the generator climbs above the battery voltage and starts to charge (called cut in volts)and the revs that most of the charging is happening. I think a large dingy with a nice solid transom and a little outboard motor would make a good test bed. Home made dynometers are not that hard to make, with a few bits of junk, a spring-gauge torque wrench and a handheld rev counter! yahoo I'm confused, no wait... maybe I'm not... |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah I agree, the turbines would benefit from a shroud. It would be like using airplane prop's for a wind turbine, they do work, but no where near as well as a turbine designed for the job. Its still a guessing game for the ideal smartdrive rewire to suit this application. I think the only way to go would be trial and error. Use a un-modified stator and start taking measurements through the tidal cycle. Watch the voltage, it could be dangerous if it goes much over 50vac. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| shredder7753 Newbie Joined: 06/01/2012 Location: United StatesPosts: 3 |
my objective, overall, is to build floating personal islands and sell them. so i decided that one of the steps along the way is to build a 1/12th scale model of my design in order to attract multi-million dollar investment money. i have to do it cheaply because so far i only raised $2,140 (US)out of the $25K I expect the overall model to cost. this generator test platform is already approaching $2K. but really i only need about 175 watts, on average, to run a pump a valve, and a microcomputer with a whole bunch of sensors. of course with it being tidal i may need to generate a lot more at peak times to make up for the twice daily reversal of flow. i think i might try the 3X4C wiring configuration: "Rewired as 4 coils in series. Suitable for low speed turbine on 12 volt system or high speed turbine on 48 volt system. General all rounder." the main reason im so concerned about all this is because i read that 12v batteries do not like to be charged with more than 15 volts. (face-palm) this is a whole new world for me. |
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