How to Wire a Blocking Diode on a Wind Generator

Written by david robinson
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How to Wire a Blocking Diode on a Wind Generator
Blocking diodes stop electricity flowing back into a generator. (Solar image by Thomas Leiss from

Wind-generated electricity is often stored in lead-acid batteries for later use. Electrical current is analogous to water flowing either way along a pipe unless there is pressure pushing it, or a valve to stop it from flowing in the wrong direction. A working generator provides electrical pressure to make a current flow into the battery, but unless a "valve" is added to the circuit, the power can flow out of the battery when the electrical pressure drops. A diode acts as an electrical one-way valve to stop this from happening; fitting one requires no previous electrical experience.

Skill level:

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Things you need

  • Wire cutters
  • Emery cloth
  • Soldering iron
  • Solder

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  1. 1

    Identify the positive wire from the generator while it is producing electricity. If the generator is a DC electric motor running in reverse, the wire that was the negative power lead to the motor is the positive lead from the generator. DC motors rotate counterclockwise, but most generator fan blades rotate clockwise, thus reversing the polarity of the wiring.

  2. 2

    Disconnect the batteries from the wiring. Cut the positive wire at a convenient point between the generator and the battery. Strip away about 1/4 inch of insulation from each end of the cut wire. Use a fine-grade emery cloth to rub the leads entering and leaving the diode until they shine.

  3. 3

    Turn on a soldering iron or solder gun and allow it to reach its working temperature. Melt a drop of solder on the tip of the soldering iron. Rest the end of one of the diode leads on the solder blob. Add more solder until it's coated; remove it from the iron. Do the same to the other end of the other diode lead and both ends of the cut wire.

  4. 4

    Hold the diode so the end with a ring marked around it is pointing away from you. Rest that end alongside of the wire leading to the batteries. Briefly apply the soldering iron to the two wires to melt the solder. Allow the joint to cool without movement. Solder the wire from the generator to the other end of the diode.

Tips and warnings

  • If the battery fails to charge after installing a diode, make sure the diode is turned the right way round.
  • On a 12 volt system, the voltage drop from a blocking diode will lose more power than you'd lose by not installing it. Blocking diodes are worth fitting on 24 volt and higher voltage systems.
  • Battery arrays can produce currents capable of causing injury or death. Do not undertake electrical projects unless you are competent to do so.
  • Never solder live wires. Doing so can damage the solder gun and destroy sensitive electronic components.
  • To prevent earth leaks draining the battery, always connect the diode to the positive wire, not the negative wire.

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