How can you tell if a motor is brushed, brushless, or a stepper?

I am trying to buy speed control but being that this is my first time building a battle bot when i bought the motors i just bought some motors off of ebay. Unaware, that there was much more to this aspect of the bot. Thank you in advance.

sort by: active | newest | oldest
KubilayY2 years ago

what is the type of this? I've searched every website related to this but never saw "brushed" or "brushless" word!

44w3509.jpg

That's because that is not a motor but a servo. It translates stick movement into a 180 degree rotation on the servo arm. It is meant to move things like rudders on models instead of providing propulsion like a motor.

Zurah5 years ago
If the motor is brushless it will have 3 connectors such as the link below:

http://www.hobbyking.com/hobbyking/store/catalog/KB204012L.jpg

If it is brushed it will have 2 connectors such as the link below:

http://www.pchobbies.net/images/brushed_motor_esc.jpg

These are examples that fit into RC Cars but they may as well be the same for whatever you are looking for.
the brushless as the name it say's...doesn't have brushes...inside the brushless motor the magnets are turning and the coil is fixed ;) these motors are slidely more efficient then brushed motors ;) peace
a stepper motor will have four leads coming off it, one for each coil 9each coil turns the shaft 90 degs, which is why it is controleabul. the only way I know to check brushed or brushless, is to open the motor up.
ok, well... i know for sure i dont have a stepper, but i dont really want to risk opening one up? can you even open them up?
1/3 of the way there. no its not a good Idea to open one up when you then want to use it agane but, yes they can be openened (if you wanted to see how they worked). you prise off the back of the motor and the inside parts can be pulled out. good it you need some high power magnets in a hurry. I have been thinking though. brushed motors produce what is called electronic "noise" and this can be detected with a radio. ifs like when a motorbike goes past and the TV goes a bit fuzzy for a second (only on analog signals though). Any way, get a small radio and set it to a good strong station, then turn on your motor, if there is any interferences with the signal, you probaly have a brushed motor. you may want to do it several times to check though.
wow, really, ill definetly try that one, ill get back to you on it. could i use like an Ihome as the radio?
I think so
Wesley6668 years ago
Usually brushed motors are harder to turn then a brushless motor, kind of like an alternator is easier to turn then a generator.
DaNerd11 (author)  Wesley6668 years ago
ooo, thanks. ill go try that.
it depends on the size as well, this may not work for small motors. If the are small motors run a 9 volt battery through it both ways and if it turns very fast it DC if it does not turn it is AC but generally most small motor are DC. Also check if it has a label. If it looks like this then I am 99.99% sure it is AC.
Electric motor.jpg
DaNerd11 (author)  Wesley6668 years ago
Well i know mine is DC but it turns slowly, high torque
probably geared down then.
DaNerd11 (author)  Wesley6668 years ago
i think it is, but i still need to figure out wether or not it is brushed or brushless.
If it is a DC cooling fan from a computer it is brushless, other then that it is probably brushed.
DaNerd11 (author)  Wesley6668 years ago
thanks
teamtestbot8 years ago
There are several ways to tell your motors apart. I assume they didn't come with any sort of nameplate, sticker, or identifying information.

Check the number of leads.
A DC motor will tend to have two, or some times four in matched pairs.

A stepper motor will tend to have four, five, or six. Four leads if it's the "bipolar" kind, five or six if it's "unipolar". These require different controllers. Generally speaking, they're also not that useful for combat bots.

A brushless (BLDC with sensors) will have three power leads and up to five or six smaller ones for commutation sensor output. A BLDC without sensors will have three.

Note that some motors have built in tachometers or encoders that will increase the number of wires. Generally, the power wires are bigger than the signal inputs.

Give the shaft a twirl.
Most DC motors will tend to rotate relatively smoothly and coast down very fast (due to brush friction). "Relatively" means that you should feel a little bit of "cogging", or ripple in the torque needed to turn the shaft. This is a result of the permanent magnets. Also, a discerning characteristic of DC motors is brush noise. Take it to a quiet place and turn the shaft, and listen for the sound of gliding brushes.

Stepper motors will "cog" strongly, and in very fine intervals (1 to 5 degrees). This is just how they are built.

BLDC motors will tend to cog at very coarse intervals (greater than 10 to 15 degrees), similar to a DC motor, but more strongly defined. Unless it's a "slotless" or "coreless" type BLDC - then it won't cog at all, and you'll have to rely on other characteristics.

Just apply power to it.
Take a small power supply like a DC wall adaptor or a small battery pack and (momentarily) touch the wires to any two *power* leads. If it's a DC motor, it should spin.

The speed will depend on the voltage rating of the motor AND how much current your makeshift power supply can put out, so note that it might try to spin but be unsuccessful. Either way, it should try and continuously go in one direction.

A BLDC and a stepper will twitch once and stop. They require controllers to sequence your power supply voltage in a proper fashion.

Open it up!
If you have a spare that you're willing to part with, open the motor. The first sign of a DC motor is a bunch of brushes and springs flying out at you. This always happens. Spend 6 hours trying to stuff them back in and proceed with building.

So you might have a brushless or a stepper otherwise. A stepper motor will tend to have 4, 8, 12 (multiples of 4) coils. The biggest telltale sign of a stepper is an rotor that is magnetic and has *many many tiny teeth* on it.

A BLDC will generally have coil counts that are multiples of three, and a magnetic rotor consisting of several large magnets or one smooth ring magnet.

These are general rules, and there's always oddballs