Turbine Charging...

fernur246fernur246 Registered Users Posts: 8
Is it possible to charge a 12 v battery from a 24 v wind turbine using a rectifier ?

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,637 admin
    Technically, yes. The battery will "clamp" the turbine voltage to ~12-15 volts (12 volts when battery is way discharged; 13.5 to 14.8 volts as the battery charges; and >14.8 volts as the battery nears full/starts equalization charge).

    Of course, there are other issues. You have to have enough wind to spin the turbine, the 12 volts does not cause the turbine to "stall" (lower voltage on turbine, higher current, higher torque required to spin turbine).

    There are other ways of doing this too... One is to get a MPPT type charge controller that supports wind turbines. The controller is programmed to let the turbine spin at optimum RPM, run at optimum voltage (probably quite a bit higher than 30+ volts), and optimum current. The MPPT charge controller will "down convert" from the "high" turbine voltage to the "low" battery charging voltage very efficiently (and probably more power harvested than if you had a 24 volt turbine direct connected to a 24 volt battery bank).

    However, the devil is in the details. Right size MPPT controller to Turbine and Battery bank. A MPPT controller that works with wind. And a good turbine+proper installation (relatively tall tower, no tall buildings/trees up wind, no turbulent air flow through the turbine from bluffs, etc.). This is not a trivial set of details/tasks.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Ethan BrushEthan Brush Solar Expert Posts: 231 ✭✭
    A rectifier isnt the correct component for that task (but is likely still needed to convert the AC to DC). A rectifier (assuming three phase) actually results in a DC voltage of about 1.35 times the AC voltage. Do you have a certain wind turbine in mind? The best thing to use for such a conversion is a midnite classic charge controller.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    "fernur246", in the early days of my alt energy life I was sold a 24 volt turbine, having been told how wonderful it would be in low wind situations, how it would start charging much sooner than a 12 volt unit. Hey, it made sense to me at the time. I soon learned however that things were not that simple. One of the major problems was as mentioned by Bill - - - clamping the 24 volt turbine to 12 volts was somewhat like putting the short circuit brake on, although not as bad. The blades were overloaded and most of the time operated in stall mode, producing very little rotational power. and thus very little electricity.
    In the end, except for providing a source of medication while I lay back in the grass and watched it spin against a clear blue sky, it was basically useless.
    Ended up I gave away the blades etc and only kept the alternator, which has been operating with a micro hydro turbine for about 6 years now, sending 36 volts to a MPPT controller that supplies a 12 volt system.
  • BisMBisM Registered Users Posts: 13
    fernur246 wrote: »
    Is it possible to charge a 12 v battery from a 24 v wind turbine using a rectifier ?


    I think technically yes you can but it's easier said than done...
  • fernur246fernur246 Registered Users Posts: 8
    Thanks all for your replies... I have a skymax 600 and the output is quite disappointing.. Oh well .. just thought of using it to charge a 12 volt bank.. I do have a mttp charge controller so I will give it a try..!
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    fernur246 wrote: »
    Thanks all for your replies... I have a skymax 600 and the output is quite disappointing..

    The one I had was very similar to yours. Very disappointing output as well. Unfortunately I believe we both got taken to the cleaners. These small wind turbines just don't / cannot produce.
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