I am trying to make a wind turbine type thing. I have 4 motors being turned at the same time to produce energy, however I would like all of their power to go to one place and i am having troubles doing that, so my question is how can I connect all 4 motors to one output?

Update for anyone with questions: all I know is that the motors are DC and from hair dryers, unfortunately they did not come with specs. I am setting up the motors to run parallel to each other connected by a gear system. Each of the motor's output is about 120 mV. I'm quite new at all of this so if this update doesn't make things clearer I apologize.

  • \$\begingroup\$ Any more details? What kind of generators? What is the load? \$\endgroup\$
    – Jeroen3
    Mar 2, 2018 at 20:43
  • \$\begingroup\$ what trouble? Circulating currents? What is the DCR of each and kRPM/V \$\endgroup\$ Mar 2, 2018 at 21:03
  • \$\begingroup\$ Do you have one turbine driving four generators or four turbines? Are you generating AC or DC? \$\endgroup\$
    – user80875
    Mar 2, 2018 at 21:43
  • \$\begingroup\$ Welcome to EE.SE. We need some feedback from you mate, or we can offer no answers. \$\endgroup\$
    – user105652
    Mar 2, 2018 at 22:01
  • \$\begingroup\$ Added update to question \$\endgroup\$ Mar 4, 2018 at 17:52

2 Answers 2


A motor used as as generator driven at constant speed is more like a voltage source than a current source. It's therefore better to connect them in series, rather than parallel. However, once driven by something 'soft' like a wind turbine, that raises the impedance and you could treat them as either, so series or parallel should work just as well, as long as the drive is reasonably balanced.

However, there are some further considerations.

These motors can be used as generators, right? Permanent magnet motors, whether brushed or brushless are OK. While wound field motors, AC induction motors and switched reluctance motors can be made to work as generators with external excitation, they are not really for the amateur.

A BLDC produces AC. Put it through a bridge rectifier to get to DC before combining it with other rectified motors.

A series connection will put the same current through all the motors. If the motors are driven by different turbines, and one is shaded from the wind, you might find that one spinning backwards, which wastes power. Put a diode in parallel with each motor to prevent this.

If the generators are connected in parallel, then a shaded turbine will be driven up to the same speed as the others, again wasting power. Put a diode in series with each motor to prevent this. The rectifier for a BLDC already provides this functionality.


With limited information, a useful suggestion would be to use diodes in a configuration such that you wont have back current through the motor or other motors. Past that point you have several options how you want too manage your multiple motors. More information is drastically needed. Are their voltage conditions you want to have? Current conditions? What kind of motors are they? Etc.

  • \$\begingroup\$ "What kind pi motors are they?"? \$\endgroup\$
    – Transistor
    Mar 3, 2018 at 8:46

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