Wind powered water heater

Now, we design a special controller for heating water directly.
The controller should be powered by two pcs 12V/3.5ah batteries. The controller will charge the batteries automatically when the wind turbine spins.
The output voltage range of controller is made to be 110~240VDC.
Before 110VDC, the controller is disconnected with water heating resistors. The wind turbine is spinning without loads.
Within 110~240V, the output voltage of controller is connected with water heating resistor automatically. The water heating resistor starts to heat the water. Our heating controller could increase the power flow to the heating element when the rotation speed of the wind turbine increases.

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