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Topic starter
2025-08-22 4:48 pm
I'm looking for insights on how to choose a permanent magnet DC motor, to be used as a generator. It's for a STEM project for a local museum. The kids will create windmill blades, attach them to the motor, and use a fan to produce wind, to see what kind of output voltage they get. How do I pick an appropriate motor? Are there any motor specs that would help? Does a 6 volt motor produce a higher output than a 3 volt motor? Does physical size mean anything? Any suggestions would be appreciated.
2025-08-22 6:00 pm
As a STEM project it seems to me that experimenting with using different electric motors as generators and comparing them to see how efficiently they can convert mechanical energy into electrical energy would be what STEM is about?
The electric motor in cars works both ways using them for regenerative braking which converts inertial energy into electrical energy which can also charge the battery while braking or going down hill.
So does a 3v motor produce the same wattage as a 6v motor given the same mechanical energy input and if so why? Answering those questions by expermentation is a STEM project.
Topic starter
2025-08-22 6:38 pm
@robotbuilder Thanks, but that is a completely different project, possibly for the future. The plan right now is for a project that will show how the shape, size, and material of the blades, can affect the output of a wind generator.
2025-08-22 8:09 pm
If it is about testing propellor designs it probably doesn't matter what motor is chosen only that the wind is strong enough to get it turning. I assume a 6v motor compared with a 3v motor will handle higher current demands (less internal resistance) while the speed of rotation will control the actual voltage output?
It is possible to read about this topic and assume it is accurate but part of science for students is surely learning how to discover the answers themselves by experimentation and calculation based on their knowledge of physics?
Commercial wind turbines shut off or feather the blades if the wind is too strong.
Will they 3D print their propellors? Lots to learn with that project, sounds like fun.
Topic starter
2025-08-22 8:53 pm
@robotbuilder I want to get the largest range of values, based on rpm, out of the motor. I'm just not sure if there is a spec data that would indicate that.
There are going to be two different ways for them to interact with the turbine. For the general public, there will be corrugated cardboard to be cut out, with scissors, and attached to a hub with alligator type clips. Then turn on a nearby fan. If they interested in more, they can sign up for an Air Academy class, where they will design the blades with TinkerCad and either 3D print them, or cut them out using a Laser.