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What makes brushless motors better than motors with brushes?

Other than the fact that they are brushless, of course, what is it about brushless motors that makes them preferable for use in RC cars and planes, etc? It seems like everyone thinks they are better, but I'd like to know why?

noobie gravatar image By noobie 50 asked Jun 24 '12 at 12:59 AM
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Brushless motors have a variety of characteristics which make the a good choice over brushed motors. 1. Commutation: Brushless motors do not require a commutator and brushes to energize the coils of wire and make the shaft spin. The friction between the commutator and brushes causes wear. http://en.wikipedia.org/wiki/Commutator_%28electric%29 2. Torque: Most brushless outrunner motors can deliver higher torque per ounce than brushed motors. 3. Cooling: Inrunner style brushless motors have the windings closer to the outside of the motor which allows them to transfer heat more efficiently. 4. Fabrication: Outrunner style motors are cheaper to fabricate than brushed motors and require fewer parts

From a hobby standpoint, brushless motors run longer on the same battery packs we use. This is because they operate more efficiently and run cooler. Outrunner brushless motors can swing a bigger prop and use less current to do so. I have flown electric planes since 1978. In my opinion the introduction of brushless motors and Lipo batteries have had the most profound effect on electric flight since it's inception.

Bill Griggs - Makermasters

BillGriggs gravatar image By BillGriggs 170 answered Jun 29 '12 at 12:02 PM
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The short answer is that there is less to go wrong mechanically. There maybe some additionally value in increased efficiency and power-to-weight ratio, but the details behind that are outside of my domain of knowledge.

Brushed DC motors require that the rotor be receive electricity. For this to happen a mechanical connection must be made to the rotor via the brushes. This interface causes friction and wears over time leading to worse performance / increased maintenance / eventual failure.

Doomcow gravatar image By Doomcow 100 answered Jun 25 '12 at 06:15 AM
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asked: Jun 24 '12 at 12:59 AM

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Last Updated: Jun 29 '12 at 12:02 PM