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DC Motor etc

Help – Brushless DC Motor Randomly Stalling

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I’m encountering a problem that I would love your help with: I have a brushless DC motor rated (1.5v to 9v).
I’m feeding a range from 3.36v to 3.95v (see the video, wiring diagram, and motor specs below).

At seemingly random times, once the motor is turned off, it will not turn back on again. It doesn’t seem to correlate with how long it was last run, or the load it had. It never stalls while spinning, only once turned off.

The only pattern I can start to gather after hours of experimenting is that if it happens to stop spinning and the shaft is in a certain position, the likely hood of it starting back up, goes down drastically. There are two shaft orientations that seem to be a hang up. But…. Not always. Not every time the motor stops in those orientations does it stall. Only sometimes. The inconsistent nature and lack of pattern in this problem has me baffled.

The severity of the stall too, seems to be inconsistent. Sometimes to get the motor going again I only need rotate the shaft slightly our of the stall orientation and then apply power. Other times, this will not work and I have to apply power and manually rotate the shaft for several gentle but quick spins before the motor will begin to spin on it’s own. Other times I have to apply power and spin the shaft manually very quickly for 20 or more rotations before the motor will spin on its own, and it’s not an immediate take over… the motor will start to spin slowly and gradually accelerate to full speed.

Any ideas at what is causing this? This project is for a Halloween party I am throwing, and I plan to make 8 or so of these particular gadgets, but they need to work reliably without manually having to manipulate the motor in order to get it to work.

I would love any insight you might have. I am brand new to small electronics.

Here is the exact motor I am using: https://smile.amazon.com/dp/B07Q44YYKG?psc=1&ref=ppx_yo2_dt_b_product_details

Here is the motor issue live in a video: https://www.loom.com/share/bbf8b3978e2a49cea628d1a052894829

Here is my wiring diagram: https://drive.google.com/file/d/1JgbZNAn3SsPm2d0HUFM-ipDk4i7HLMN_/view?usp=sharingmotordcbrushless-dc-motorShareCiteEditFollowFlagedited 2 hours agoTransistor151k1111 gold badges161161 silver badges338338 bronze badgesasked 2 hours agoBrenton Wiberg1111 bronze badge New contributor

  • 1It’s ‘V’ for volt. Welcome to EE.SE. – Transistor 2 hours ago 
  • @Brenton Wiberg. Good day. (1) I admire your TikTok. I would give it 9.5/10. (2) Just to clarify, usually BLDC has more than two wires. If it is just a two wire guy, then 9/10 that it is just a ordinary DC motor. (2) Your too precise spec of “3.36v to 3.95v” make me and even hobbyists laugh: me small electronics ninja just over power it a little bit, say to 4.5V, and the sticky motor won’t statr/restart problem might disappear. / to continue, … – tlfong01 2 hours ago   
  • (3) Stalling intermittently, and inconsistently at one one or more random positions usually has at least one cause: bigger fiction at those points (9/10 you don’t have any gear inside the case. (4) Your question description is excellent, I would give 9/10 marks. / to continue, … – tlfong01 2 hours ago   
  • (5) You TikTok is asking for “professional” advice, and that makes me hobbyist (even at ninja grade) hesitate to reply. :), (6) It is not clear if you are using a battery. If yes, then the battery usually gets tired after sometime (did you say “hours”?) . So let her take a break to recover, or give a pad on her shoulder. – tlfong01 2 hours ago   
  • (6) Your RT300 toy motor is popular among STEM/solar power hobbyists. I did once played with it and I found it needing only tiny (solar) power to move, but too weak to move any thing heavier than the little pretty plastic fan recommended. Ref: Techni Motor RT-300-11400-18 (3V) (i) aliexpress.com/item/4000073920466.html (ii) chinese.alibaba.com/product-detail/… – tlfong01 1 hour ago    
  • You might like to read Jameco’s professional spec: Jameco 3 Volt DC Motor – 2400 RPM jameco.com/z/… Spec: 3V DC Motor – 2400 RPM, Good for solar applications, Nominal voltage: 3VDC, Voltage range: 1 – 6VDC, Current @ maximum efficiency: 0.065A, Speed @ maximum efficiency: 2400 RPM, Torque @ maximum efficiency: 4.3 g-cm, Sleeve bearing, Efficiency: 56.4%, Terminal type: 3″ wires, Shaft diameter: 0.078″, Shaft length: 0.19″, Size: 0.960″ diameter x 0.491″ depth, Screw Mount Dimensions: M1.7 x 0.35, … .. – tlfong01 1 hour ago   
  • PS – Jameco motors are perhaps 3 times more expensive, but 3 times less “sticky”. 🙂 – tlfong01 1 hour ago    

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1 Answer

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Probable cause

You may have damaged the motor commutators with high voltage arcing, from excess flyback high voltage on turn off.

A flyback diode is needed for your next motor.

enter image description here

Alternatively you can generate voltage with 3 anti-parallel diodes.

p.s. They might not be brushless, then the armature got burnt with carbon.

If brushless, then the Hall sensors are damaged/ degraded from reverse voltageShareCiteEditFollowFlagedited 2 hours agoanswered 2 hours agoTony Stewart EE75120k33 gold badges4444 silver badges162162 bronze badges

  • 1The ad doesn’t say they are brushless, although you can get 3V BLDC motors with only 2 wires just like fans. – Tony Stewart EE75 1 hour ago

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