# How to locate brushless DC motors for generators



## 100model (Oct 2, 2013)

Hi everyone  

Some have asked where do the brushless DC motors come from I use as generators. I made a video showing where they come from and how to locate it in the appliance.  [ame]http://youtu.be/RYCWY52yVVQ[/ame]


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## petertha (Oct 3, 2013)

Fascinating. I like how you disemboweled those surplus appliances to harvest the goodies. My printer will be making a detour to the shop before the recyclers! I'm curious of a few things:

- lacking an old PC or printer, is there anything substantially different between a hobby shop grade motor in terms of utilizing it for a generator?
http://www.hobbyking.com/hobbyking/store/__7520__2205C_1400Kv_Brushless_motor.html

- you mentioned your preference for size (that big diameter model). Is there a difference between an in-runner vs. outrunner for use as a generator?

- I'm familiar with kv rating & voltage limits on hobby motors (only because they spec them). But how do you go about determining these values on an 'unknown' motor from an appliance? Or is it more just matching power (wattage?) to your mechanical engine?

- (I'm not electric savy so bear with the dumb question) can you explain the wiring/circuit in laymen terms? I'm familiar with +/- DC power -> speed control -> 3 input commutated wires to motor. Now I think you have mechanical drive engine -> motor, so 3 output wires > (no controller) > lightbulb DC load?


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## mu38&Bg# (Oct 3, 2013)

The hobby king motor could be better than than what's in a tape drive, copier or whatever. Those units go for low cost first and have thick laminations. Finding large motors is difficult as well. Any motor can be used as a generator, bruhsless DC, AC asynchronous, brush DC. Constants are easily measured, resistance by four wire method and Kv by measuring generated voltage at RPM. A brushless motor just needs a 3 phase rectifier on the output. The motor from the printer will probably be wound at a much lower Kv than an RC motor, so more useful for a model generator.

This is how the outrunnner started in RC. People scavenged them from equipment, installed improved magnets and wound them to an appropriate Kv. These days some people rewind existing RC motors to improve copper fill, almost nobody scavenges stators anymore. Building outrunners is not what it was 10 years ago.

Greg


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## 100model (Oct 4, 2013)

petertha

Hobbyking motors are wound for large currents so to use them as a generator it has to spin really fast to get a decent voltage. I like the large dia. motors because they don't have to spin as fast as a small one to get a 12v light to work. There is no difference between a inrunner and a outrunner.

It is a case of try it and see how well it works. The ones I have experimented with range from 50 watts to 100 watts output. The lights are used to load up the turbine so it will not over speed. 

The 3 input commutated wires to motor are the output wires from the alternator and if you want DC output use two bridge rectifiers. I prefer to use the AC output so the voltage can be run through a transformer to use 240 volt lights.


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## 100model (Oct 4, 2013)

petertha

Hobbyking motors are wound for large currents so to use them as a generator it has to spin really fast to get a decent voltage. I like the large dia. motors because they don't have to spin as fast as a small one to get a 12v light to work. There is no difference between a inrunner and a outrunner.

It is a case of try it and see how well it works. The ones I have experimented with range from 50 watts to 100 watts output. The lights are used to load up the turbine so it will not over speed. 

The 3 input commutated wires to motor are the output wires from the alternator and if you want DC output use two bridge rectifiers. I prefer to use the AC output so the voltage can be run through a transformer to use 240 volt lights.


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