Homemade treadmill wind gen. (Wiring options)

YostFMXYostFMX Solar Expert Posts: 94 ✭✭✭
I've got to treadmill motors,
#1: 120 VDC, 14 AMPS (2HP)
#2: 100 VCD, 14 AMPA (1.5HP)

I both will have 10' PVC blades 30'' long, tri-blade. I was going to wire them the PV way but found out you have to wire with a "dump load", I don't want to do that... so the question is what wind speed is too much to let it "freewheel" in, as in when will it blow apart? I still want to wire it PV style and just stop the wind gen. when wind get too fast. Will this work?

Oh and what Watts should I get out of them a different RPMs? I tested at 900 RPM with a drill and it was 166 Watts and 160 Watts but with no load.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,049 admin
    Re: Homemade treadmill wind gen. (Wiring options)

    I will wave my hands first... :roll:

    The issue with a HAWT is that in order to get reasonable power at lower wind speeds, the diameter and pitch of the blades needs to be fairly aggressive to get supply the torque and RPM needed to turn the generator... If the generator is unloaded, the freewheeling speed is high enough that the turbine will over speed in heavy winds (more than 20 MPH, 40 MPH... I don't know).

    There are several methods for controlling over-speed. One is to keep the load (battery) on the turbine and control the RPM (and you need a dump controller+loads to keep the battery bank from overcharging in a wind storm).

    Another is to short circuit on the turbine and turn on the dead short such that the rotor requires so much torque that the blades simply cannot get up to speed. There can be an issue with this method--the energy resisting rotation has to be dissipated somewhere. That is in the wiring of the generator--which can overheat and cause failure of the wiring, Bridge Diodes, and/or cook the rotor.

    And there are of course the mechanical means... Brake, tail to turn blades 90 degrees to the wind, offset mounting that the harder the wind blows--the more the blades face away from the wind, changing the pitch of the blades (feathering) and such...

    In general, a long lasting installation combines the electrical speed control (dump loads, shorting) with a mechanical speed control too (brake, feathering, furling, etc.).

    I am not quite sure how you measured your energy of the motor when connected to the drill...
    • Power=Volts*Amps=Watts ...
    Normally, Volts and Amps are related to RPM and to each other (the higher the amps, typically the lower the volts). So, if you have 160 Watts, you have xVoilts*yAmps. If you have no load, (amps=0), then Power=Volts*0amps=0watts.

    When connecting a battery bank, a low voltage bank (12 volts) may allow the turbine to gather more energy in low speed winds (turbine needs to turn fast enough to generate 12 volts and amps>0). In high winds, the voltage and current can be higher--but few people have enough wind to run a (for example) 48 volt battery bank efficiently (depends on the generator windings and RPM characteristics).

    You will need to look at your "generator"--you may need a gear box (2:1 speed increase type) and the gear box may be useful for supporting the blade/wind loads. Most motors/generators are not designed to reliably handle large thrust and offset loads.

    Back to your questions... I have no usable answer for you. You might wish to take a look at these two sites:

    www.otherpower.com (there is a forum there too) DIY Wind--lots of it
    www.builditsolar.com (lots of projects, including wind)

    If you are serious about looking a generating a goodly amount of power from your wind turbine, you might look at Midnite Solar -- They have a "Classic" MPPT style controller family that not only is avialable for solar PV arrays--It is available for MPPT use with Wind Turbines. Testing by poster Halfcrazy indicates that a very large mount of increase in power collection (battery charging) can be had with an MPPT controller for wind turbines. The controller is not out yet--but hopefully months away (???--I am not connected in any way with Midnite Solar).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Truth SquadTruth Squad Solar Expert Posts: 126 ✭✭
    Re: Homemade treadmill wind gen. (Wiring options)

    "I both will have 10' PVC blades 30'' long, tri-blade. I was going to wire them the PV way but found out you have to wire with a "dump load", I don't want to do that... so the question is what wind speed is too much to let it "freewheel" in, as in when will it blow apart?"

    The problem there, my friend, is you have to actually test the turbine to find that out. We can't know the structural integrity of the PVC, for one thing. Quality being a variable among various manufacturers.

    One other thing. If you got the 900 RPM figure off the spec plate of the drill, be advised that's the no-load speed of the drill.

    Good luck with your endeavor.
  • YostFMXYostFMX Solar Expert Posts: 94 ✭✭✭
    Re: Homemade treadmill wind gen. (Wiring options)

    Thanks...

    I really just want to sell the motors and not use wind now and just go with the PVs. The motors and everything to make them is free so I wan't to try and use them... I don't know? What about hooking AC water heater elements directly to it (no batteries or controller) to heat 5 gallons? Would that work as a small hot water heater?

    The wind gen will be on the top of a 13' tall barn shapped building. Maybe 4 over the top...

    What do you guys think I could sell it for on ebay (all built and ready to go)?
  • Truth SquadTruth Squad Solar Expert Posts: 126 ✭✭
    Re: Homemade treadmill wind gen. (Wiring options)

    Sell it on eBay? Let's not go there...
  • YostFMXYostFMX Solar Expert Posts: 94 ✭✭✭
    Re: Homemade treadmill wind gen. (Wiring options)

    Would it work as a 5 gallon water heater wired right to heating element?
  • BB.BB. Super Moderators, Administrators Posts: 30,049 admin
    Re: Homemade treadmill wind gen. (Wiring options)

    It can... A 120 Volt or 240 volt element will run OK at lower voltages (AC or DC). In general, the output of the element will fall with the square of the voltage.

    For example, a 240 volt element will be 1/4 the rated power at 120 Volts, or 1/8 at 60 volts. You can scale the elements to your desired power level/voltage levels. Parallel a couple for more current, etc...

    V=I*R; R=V/I
    P= V^2 / R = I^2 * R
    R=V^2 / P

    Practically speaking, getting electricity from a wind turbine to heat water may not be very useful. However, if you have the hardware and want to run some tests.

    Note, if it where to really develop a lot of heat--you would need, at the very least, a T&P Valve (temperature and pressure safety valve) to keep things safe (see old Mythbusters show showing explosive force cause when T&P valve is removed/plugged).

    Also note that a normal water heater turns off the element when the temperature set-point is reached. Removing the dump load from your turbine--which can cause other issues.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,610 ✭✭✭✭✭
    Re: Homemade treadmill wind gen. (Wiring options)

    2 problems with treadmill motors:

    1) not even intended to be weatherproof

    2) bearings, the treadmill rollers are takeing all the weight, when you load the bearings with wind, that will make them un-happy. You need to emualte the gear or belts from the original configuration, to get some "miles" out of the bearings.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • Truth SquadTruth Squad Solar Expert Posts: 126 ✭✭
    Re: Homemade treadmill wind gen. (Wiring options)

    Good points, Mike.
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