Half a year after first tries (failed) to wind a DIY motor from Banggood (it's not in offer any more BTW) I gave it another try. This time, with new tricks in my sleeve and new ESC. It ended up, well, watch the video…
Is it worth to soft mount flight controller? Are gyro pads I recommended here better than rubber stand offs? I feel that they are better, but I do not have any solid data to prove it. So I can only tell, that I find them better and that is all. But, I can answer the question is it worth to soft mount flight controller at all. The answer is YES and here is a proof…
The problem of twitching motors
After I updated my 5″ racer to stronger motors (EMAX RS2205S 2300KV over RS2205 2300KV) I noticed something very very irritating: twitching motors. When throttle was in more less middle position or after rapid throttle change, twitching from motors was very audible. Quad was flyable, but performance was very low. I had to reduce yaw P gain by more than 50% not to see those twitches in FPV footage!
Blackbox log revealed the truth: from time to time, strong vibration was getting into yaw gyro traces. I also localized the source of those twitches: stronger motors with more torque and higher radial acceleration were able to shake whole machine when frequency was close to the resonance frequency of the frame.
Latest update on the topic of DIY motor kit from Banggood (DIY Assemble 2204 2-3S Brushless Motor 0.42*2.8 Copper Wire with Motor Cap Banana Plug): I give up. For now, at least.
In total, I tried to wind this motor 6 times. In every single case it ended in the same way: one of the phases burned. So, it's either me, or this kit. I've verified winding directions and termination schema for at least few times, and if I didn't missed something extremely obvious, I did it in a right way. I even verified winding directions during "unwinding". So I start to suspect, that this motor is either no 12N14P DLRK (not very probable), or it should not be winded with 0.42mm wire. Next week I will order 0.20mm wire and try one more time…
This is a winding schema I used:
Poles goes as follows: AabBCcaABbcC where capital letter is clockwise, while small letter is counter-clockwise.
Phases were connected like this:
Sure, I could have done something wrong. But not 6 times in a row…
Just like it was expected, my first attempt to wind a brushless motor (12N14P) was a failure. Probable cause: short circuit between phases and my creation released magic smoke.
Then I tried for a second time, and failed again. This time less, no smoke, but motor overheats and does not want to start most of the time. I suspect this can be an ESC problem (Emax 30A) that is configured for DampedLight. Perhaps motor is rotation too fast (no load after all) and ESC tries to slow it down. Hard to tell. Tomorrow I will add a propeller and disable DampedLight. Maybe it will help. I will also try WYE configuration. Right now phases are connected in Delta setup.
China is such a magical place… among all those affordable things you can buy there, there are those not so useful, but still affordable things that, for sure, you do not need. Just like DIY Assemble 2204 2-3S Brushless Motor 0.42*2.8 Copper Wire with Motor Cap Banana Plug.
As you can see on a picture above, it is a motor that you have to assemble by yourself. Wind the coils, install bearings, learn the difference between Delta and Star configuration, and so on and so on… Oh, and there is absolutely no manual. So even number of wire turns is a mystery. I suspect something around 10, but who knows.
Tomorrow will be the first attempt to assemble it. I hope magic smoke will not appear…
You finished your build, you connect LiPo, power up flight controller, apply throttle (no propellers of course) and you see that one or motors are spinning in wrong direction. How to fix that? You can not do it, for example in Cleanflight Configurator. ESC communication protocol does not allow to change BLC motor direction.
There are 4 ways of dealing with this problem:
- Hardware way that works all the time: swap any two motor wires. Does not matter which, just take any two and swap them between motor and ESC: A with B, B with C or A with C. If you have bullet connectors, it's simple. If you soldered wires to ESC pads, you would have to resolder them.
- If you have BLHeli ESC software, BLHeliSuite allows to change motor direction without swapping any wires. Connect to ESC with BLHeliSuite, and change Motor Direction option. This works only with BLHeli enabled ESC, and only on Windows.
- Most of ESC allows to change options like motor direction via transmitter. Exact procedure differs from manufacturer to manufacturer, but usually it looks like below. For exact procedure and possible options refer to ESC user manual!
- Connect ESC to radio receiver throttle channel or use flight controller configurator software Live mode. Remember to remove propellers!
- Throttle UP
- Power ESC, it will start to beep signaling number of cells
- Keep throttle up until you hear a sequence that confirms programming mode has been entered
- Wait to hear beeping sequence indicating Motor Direction option
- Throttle DOWN
- Wait until you hear beeping sequence indicating desired rotation direction (normal or reversed)
- Throttle UP
- Setting will be changed and after next power cycle rotation direction will be changed
- Sometimes special programming cards for ESC can be acquired. They somehow automate procedure from point 3 but work on the same principle. For exact programming procedure refer to programming card user manual.
EMAX programming card photo 
One of the things that can happen to brushless motors, specially outrunners, is broken off magnet. Stronger crash, or even extensive vibrations, can cause one one small magnets located in motors bell to tear off. After all, they are only glued to rotating part of motor.
- If magnet stays inside motor, it will either rattle, or more probably block motor completely. It will stop spinning, and will not start again. Do not try to force it, it will only get worse,
- If magnet will somehow leave motor interior, motor will usually continue to spin. More, multirotor or a fixed wing plane will be flyable. Of course, motor will loose some power, there might be some jerkiness, excess vibrations, but it will keep to rotate.
When case one happens, you can easily see it happened: motor blocked completely or very rattly. Immediately disconnect power, magical smoke is very near. In case two, motor when pushed with finger will spin, but jumpy, like this:
Plus, due to weight imbalance, motor will be a source of huge vibrations.
Can I fix a motor with broken off magnet?
Yes, if you have a magnet, it can be glued in place. If it stayed inside motor, you already have it. Just remove shaft clip and pull motor bell. If you have lost broken off magnet, you could get a new one. Maybe to buy it, but better option will be different damaged motor as a donor. The same type of course.
I’ve bought first Turnigy 2730 1500KV brushless motor by accident. I needed something small and cheap for Depron airboat. Then I needed something similar for a Depron airplane. At the end, in 6 months, I owned 3 T2730 1500KV motors. Not all of them survived the experience. One got lost in the middle of a lake with the rest of airboat it powered. Second got burned what I forced it to power too big propeller. Third one still lives and this type is my first choice for anything up too 400g of weight.
Since I was lacking some power in my Reptile 500 quadcopter, I was considering switching my Turnigy MT2213 935KV motors to something more powerful. Last previous weekend kind of forced me to make that switch: I destroyed one motor while trying to replace bearings. Being forced with lack of motors I’ve decided to stay with 3S LiPo, AfroESC and 10″ APC propellers and buy motors that would deliver more power while being compatible with rest of my setup. So I have chosen EMAX GT2218/09 1100KV.
Why them? Mainly because they were meeting my requirements and being actually available and within reasonable price.
- Weight: 80g,
- KV: 1100,
- Max power: 312W,
- Max thrust:
- 1380g on APC 11×3.8,
- 1290 on APC 10×4.7
- With long shaft at the bottom, so can be mounted in front and behind an firewall,
- GT series (Grand Turbo, woot woot) for “hi-tec” and “pro” models (such a nice name…),
- Black (!),
- Mounting holes: 16x19mm.
My 250 class quadcopter project is slowly coming to a successful (hopefully) end. Finally had some time to assemble motors and ESC.
Since I wanted to have rather standard setup with 5×3 propellers, I had no super high demand on ESC, I’ve decided to use Turnigy Multistar 10A V2 ESC preflashed with BLHeli software available at Hobby King. Why them? Cheap, already flashed with BLHeli so no need to to flash at home and 10A is enough to drive 5×3 props. And it’s also enough for 6×3. Just in case.
Motors are also Turnigy bought at Hobby King with 50% discount few months ago: Turnigy Multistar V2 2206 2150KV “Baby Beast”. After discount they were super cheap: $7.5 apiece. And they are green, what goes nicely with carbon fiber ZMR250 frame.
Right now motors are not soldered directly to ESC, I’ve only removed 2mm bullet connectors from both motors and ESC. Waster on space. I’m still thinking about where to put those ESC, so for first few weeks there will be some extra cable between them. Later we will see.