rigging up a dump load

Sewardsfolly
Sewardsfolly Registered Users Posts: 4 ✭
in Wind Power Generation #1
I am a gadet guy having fun with tinkering. My goal is to set up a small turbine system from which I can run some 12 v led lights to light up my kids tree house and maybe even a reading chair in the house. I have successfully created a (it used to be a ceiling fan) wind turbine and am now setting up the battery bank and dump load. Numbers? numbers?

I believe that this turbine will create up to 90 volts which never exceeds 2 amps. I have two deep cycle batteries of differing amp hour ratings and now wish to find an appropriate appliance to hook up as a dump load (i.e.-a coffee maker? with heating pad or something like this). Warming up my water would be wonderful but I'm still just tinkering. I have found a charge controller on ebay with dump load; it is a Charge controller ADG BRAIN only 12 volt wind turbine solar panel 440 10,000.

What is a realistic dump load? Is it really necessary with my light weight output? Would simple disconnect of charge load from battery be sufficient? According to the control charger, I will be able to "program" it for specific volts. One sight made the dump load calculations so complicated. Any ballpark general safe things that I can do to dump?

You time and patience is greatly appreciated.
Sean
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Comments

  • Sewardsfolly
    Sewardsfolly Registered Users Posts: 4 ✭
    #2
    I forgot to mention that i have already raised the tower using old windsurfing mast and wood foundation and old sailboat shrouds as stays. I live in a place where there is plenty of wind 20 knots in summer daily and wind during the winter storms.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #3
    The whole idea of a dump load is to provide an always available mechanical load on the turbine so that it does not run away at high speed in a moderate to high wind and self destruct (with the possibility of also destroying things that the flying blades hit on the way down.)

    Even if you have designed a furling mechanism to move the turbine parallel to the wind if the speed gets too high, that mechanism will require some time to react or may fail and only the load in the generator will be keeping the turbine speed under control.
    Note that the power output of a wind turbine increases as the cube of the wind speed, so that generator and the dump load will have to be able to handle a load that is potentially higher than the design output of the generator.
    The last thing you would want to do is open the circuit to the generator when the batteries do not need any more charge current.
    (Similar considerations about overspeed and a dump load apply to water turbines too.)
    SMA SB 3000, old BP panels.
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  • Sewardsfolly
    Sewardsfolly Registered Users Posts: 4 ✭
    #4
    inetdog,
    thank you for the wisdom. OK. I hear YES YES YES to dump load and its forever importance. I have the charge control that offers the dump load and setting voltage limits to start dumping. Now I am looking for cheap and easy dump load options with 0-100 volts 2 amps max system. What is the right heater to link to this system....  a coffee maker?, or a bigger heater? and candle warmer? etc?
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  • Sewardsfolly
    Sewardsfolly Registered Users Posts: 4 ✭
    #5
    a waffle iron, an electric skillet, etc.??
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    edited November 2015 #6
    Why the 2A maximum?
    To completely brake the turbine the dump load might need to dissipate more than the maximum rated output current of the generator. Or at least draw more current at a lower voltage even if not getting the optimum power output of the generator under the circumstances.

    The "emergency" braking system for a wind turbine is to short out the output windings completely.
    SMA SB 3000, old BP panels.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #7
    Sewardsfolly said:
    a waffle iron, an electric skillet, etc.??
    NO  many appliances have thermostats in them, the coffee maker brews at 800W for 10 min, then drops to 200w for the rest of the day, And it has a "thermal fuse" to keep from burning your house up.   BAD

    You need an absolute reliable load that can handle the power generated in a 6 hour gale, a large, fanless air cooled resistor bank, a 500 gallon water heater, or something that will not let you down.
    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 ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • WaterWheel
    WaterWheel Registered Users Posts: 387 ✭✭✭
    #8

    Here is what I used to use back when I built some hydro turbine generators.

    http://www.colemanair.us/vp_asp/scripts/shopdisplayproducts.asp?id=13&cat=Diversion+Loads+(Resistors)

    You can get individually little heating elements to burn off excess power.      Size your element about 20% larger than your max output.     Too large of a resistor will provide enough load to stop your turbine which isn't the goal, just enough resistor to burn the excess energy with a 20% safety margin.

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #9
    Note that "too large a resistor" above refers to a LOWER resistance in ohms.
    SMA SB 3000, old BP panels.
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