Summertime Temps.

n3qikn3qik Solar Expert Posts: 741 ✭✭
I have a homebuilt wind genny, I have noticed it is not producing as much power as it did 3 months ago. I think it has to due with the temp being 60-70 degs.( warmer but less dense air) instead of 30-40 degs. ( colder but more dense air ).

Am I right with this thinking or should I look at there is a problem??

Comments

  • mike95490mike95490 Solar Expert Posts: 8,817 ✭✭✭✭✭
    Re: Summertime Temps.

    The only thing temperature should affect is your rectifier diodes. If they are not likening the temps, replace them with nice sturdy Schottky diodes, for a couple of bucks apiece. Measure the voltage drop across them with a O'scope, you may find a bad one, or they all are sick. They WILL need a heatsink, and maybe they are not properly thermal bonded to the the heatsink, or the cooling vents are plugged.
    If you get magnets hot, they loose magnetism - I have no idea what would heat them up, and if the wires get hot, they burn a short or open. Compare resistance of each wire coil, see if one is way off from the others.

    But generally, they are not heat sensitive like solar PV panels are.
    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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  • BB.BB. Super Moderators, Administrators Posts: 30,638 admin
    Re: Summertime Temps.

    Assuming that you have an accurate log of wind speeds--then we can look at Density Altitude--or basically, assuming a fixed pressure altitude (basically, dependent on weather) you can compare the density of the air at differing air temperatures.

    Here is a readable link to a Density Altitude Compensation Chart (scroll down the page, near the bottom).

    Assuming you are near sea level, the difference in altitude between 30F and 70F at sea level is, roughly, -2,000 feet (cold) vs +500 feet (warm).

    Using the Bergy 1kW wind turbine spread sheet (.xls), this decreases the wind turbine output by about 6.9% because of the increased temperature...

    Could you see it on your system--I am not sure unless it is pretty accurately instrumented.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Summertime Temps.

    Thanks guys,
    I have a wind gauge, but no logs.
    During to winter I saw 5-10 amps, summer seeing about 1-5 amps. Both of this numbers at 20-30 MPH winds.

    Since it was made from scrap parts, I guest I can't ask too much from it.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Summertime Temps.

    Today, she was bucking like a bronco. So I lowered the pole. Found two problems, first, the UHMW bearings are bad, second, one blade loosed an 6" part of the tip and another has a crack in it. I built it from scrap parts, guess it's time to return them back to the scrap pile. :grr:cry:
  • System2System2 Posts: 6,290 admin
    Re: Summertime Temps.

    OUCH! It always hurts when you put a lot of time and effort into something that fails after a while. I know, been there, and you know the rest.
    My 14 foot prop eventually suffered an "uncontrolled disassembly" during a storm. Most of it, I never did find, part of it was stuck in the barn roof like a broken knife in a pumpkin, but while it lasted, it was a sight to behold and worked beautifully. Alas, all good things must come to an end :(

    Looks like your center blade has also developed a crack.

    Peace
    Wayne
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Summertime Temps.

    Yep, that was about to fail also.

    Have not found the missing part yet, guess I better start checking the neighbors roofs.
  • BB.BB. Super Moderators, Administrators Posts: 30,638 admin
    Re: Summertime Temps.

    UHMW PE Bearings? Aren't those plastic bearings for pretty low RPM ( maybe a few hundred RPM at most--depending on shaft size) and relatively low temperatures (180F maximum--depending on composition)?

    I don't know which happened first... Bearings went out of round and fractured you blades or the blade failed and pounded out the bearing...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Summertime Temps.

    My bad, forgot to type the UHMW is for the yaw bearing. Opps.
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