I understand there are 2 main types of motors: brushed and brushless motors. How can you tell visibly what type of motor you have without researching/reading the manual?

  • Can you make this relevant to drones/flying? This is otherwise a pure SE.Electronics question. – Kenn Sebesta Apr 17 at 16:03

As a general rule-of-thumb, brushed motors usually have two wires, while brushless motors generally have three.

Source: https://www.thinkrc.com/

Image source

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  • Intersetingly, all BLDC are PMSM, but we typically only call it a PMSM if it has 4 wires, where the fourth wire is the star point. we usually call is a PMSM. If the four wires are controlling two coils, it's a stepper motor. If it's a 2-wire BLDC, then it's basically a Dyson. – Kenn Sebesta Apr 17 at 16:02

Good question.

Brushed motors are generally thin silver cylinders with a shaft that look like this:

enter image description here

Photo source: https://oscarliang.com/fpv-micro-quad-beef-board/

Brushless motors, however, will generally have visible copper windings and, most often, have the outside or ‘bell’ rotate:

enter image description here

Photo source: https://www.hobby-wing.com/emax-lite-spec-ls2207-2400kv-2550kv-brushless-motor.html

There are differences - you might not always be able to see the brushed motor as some drones use gearboxes to increase torque, so another way to tell is that if you can see the wires, brushed motors have two and brushless motors have 3.

You will also not very often see brushless motors on a drone using gears, however it is common for brushed motors to have them.

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  • There are many instances of brushless inrunners. An outrunner is usually a good sign of a BLDC, but an inrunner is ambiguous. – Kenn Sebesta Apr 17 at 16:02
  • @KennSebesta yep, that’s why I said they generally have a rotating bell. For the most part, the brushless motors we use will be outrunners so I decided I’d try to simplify my answer. – Drones and Whatnot Apr 17 at 16:04
  • The wire idea is simply not true. For example, here is a 'brushless' motor with two wires {picture}. and here is a DC motor with more than 2 wires for drive {picture} – tuskiomi Apr 18 at 3:48

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