Quadcopter Motor Damaged? How to find out. With a drill.

[@jonefive5195]

Once upon a time ago I worked in a robotics lab along side various scientists and I have to say you have a skill for explaining concepts and I am delighted that you are making videos like this. I feel that a lot of young people are interested in this hobby and you exposing them to this type of science isn't just an entertaining tip, it is a public service. Thanks for what you are doing and please keep it up.

[@baggszilla]

Watching this 3 years later and still learning something every day! Thanks JB!

[@Just-A-Guy-Learning]

Josh you are nothing short of brilliant. Thank you for all that you do for the community.

[@MBrulla]

Years ago, early in my career, I worked in a generator plant as a materials analyst. I got to watch them make GIANT brushless motors from scratch, the windings and all. It was so freaking cool. This was a good video, and I know I'm late to the party...it randomly popped up while I was looking at how to test ESC mosfets.

[@thanatos3511]

I was skeptical when I saw the title...until I realized it was you, Bardwell! Helped me quickly rule out a motor issue on my Matrice100, even. You're a lifesaver. Now, to figure out how to test these esc's....

[@johncgibson4720]

Excellent. 5 years old video and still sharp and good.

[@drewx10]

Joshua, This was so helpful. I smoked an ESC when my motor was blocked by some grass. The windings of the motor were a little darker, but the motor's output voltage across the 3 leads match all the other motors on this quad. I should be able to get back operational now thanks to your video.

[@primitivefpv6660]

Hey Joshua. I maintain pumps and fans for a living and the meter we use to check 3 phase motors is a meg ohm meter. The ones im aware of use 1000vdc or 500vdc to test from each phase to ground (motor frame). Usually what kills the motor insulation is heat moisture and vibration. Motors with good windings will have meg ohm above 1000meg ohm and once they get close to 400meg ohm you know your close to failure. In my experience its kinda rare for the winding insulation to breakdown before the bearings or motor leads. Thanks again for the content!

[@brianbutcher7409]

FYI, Josh you are the coolest weird dude I know, you do more to help out the FPV comunity than anyone else out there. Please keep on being you and thank you for all the great videos.

[@505Goat]

I really appreciate your channel and just felt that you needed to know that. Thank you for all of your info in this hobby!

[@JoshuaBardwell]

Thanks!

[@TravorAhern]

Joshua Bardwell its ok to say 'your welcome '

[@miken.3981]

My favorite J. Bardwell quote of all time: "For you know when we've had a few beers or something else maybe."

[@micsherwood4930]

GREAT! This was an excellent eye opener. I had a clear build but just when i went to bind the AIO was shorting out. I cleared each motor off the board, one by one, and retested for clear function until I found the motor causing the trip. I did this test but the motor tested good. When i put it back on to test it would trip. The light came on and I found that i tightened one motor screw too far and it hit the windings. Changed the screw size and all is clear now! At $25/motor, that saved me some money and a couple weeks waiting for a replacement.

[@gustavgans6075]

Volt, Tesla, Henry... maybe one day the quality of a quad will be measured in josh´s

[@frankbarajas]

Awesome! Or perhaps "JB's"...lol

[@michaelaustin6000]

I think a unit would sound good if measured in "Bardwell's"

[@sunshynff]

I love philosophical discussions in the realm of science over a couple beers! I didn't start truly enjoying "the science of things" til my 40's, about the time I got in the hobby, hmmm?? Anyway, been in the hobby 6-7 years, you can still put a check by my name as mind blown from this info, thanks again Joshua for a great video!

[@butteredbutter420]

Your right. That blew my mind. Never thought of the motor putting out AC volts but definitely makes sense. This is why we have you Mr Bardwell.

[@IanF-FPV]

Videos like these are so great for beginners and experts Josh....Thx for this

[@mike216ism]

Im a tech in food industry. You could always pick from any two leads and keep checking from lead to lead for resistance or continuity for a bad phase. That could indicate a break in a winding or wire. I've see that on older motors that were in use and have failed. Usually a bearing goes or for whatever reason it was over heated and the insulation broke down and something goes to ground. AC motors are extremely reliable and usually never fail unless poor maintenance was too blame. I've seen them run under water (not water resistant rated) and run covered in sugar for years. There pretty bad ass. AC motors have taken off the past few years in our hobby and in the power tool industry. Another excellent video!

[@Cyberdactyl]

Cool trick Joshua! Thanks for sharing. One other thing you can do if you're worried about damaging the threads is put some shrink on the post.

[@kennyFF033]

Maybe not mind-blowing (I used to rebuild large motors 20 to 100+ hp) but I certainly learned something! Never thought of testing voltage to check motor. We always used meters on the big motors, but that makes sense... big motors, big coils, more resistance... little quad motors, well, much smaller I'd say. Brilliant idea and well done video.

[@JoshuaBardwell]

It really depends on the number of winds around the pole, not so much the size. Although you don't typically see high-kv giant motors, at least not on RC vehicles.

[@PuttingOnTheFoil]

Great tip! For some reason it never occurred to me that a brushless motor is an AC generator when mechanically driven, even though I knew a brushed motor is a DC generator in that way.

[@Martin1519]

That's a cool trick, I had no idea the motors could produce power. I learned something today. Thanks Mr Bardwell :)

[@noladroneworxllc3115]

I know you have a cool timing light. But FYI you can find the drill' s stated rpm on the label near the serial / model number. Great test for us layman. And was blown away.

[@noladroneworxllc3115]

And have you ever had one motor sag on punchouts? Tried r/r esc - and still does it. FC is next.

[@JR-yr8xm]

Thank you for this Josh. This info is preventing me from losing my mind in trying to make some kind of home generator. Items in mind are 1 or 2 solar panels, only if needed, an alternator, something to spin the alternator without need too much or any power , etc. Im having a tough time because i dont know enough of electronics to help me make good/efficient decisions. That's the frustrating part.

[@PIXscotland]

You should set up a rig with a servo tester, an ESC and a drive motor. Use this to feed the motor under test. Varying the speed of the drive motor over time and charting the output will give you a table of data showing the KV output at different speeds. You could create a nice graph of (unloaded) KV at different speeds using this data.

[@kurtzFPV]

Thanks. This worked great. Went through a group of questionable motors I'd had sitting around. By the way, a dremel tool works great for smaller motors.

[@p010fpv]

your timing couldnt be more perfect. i had my quad fall out of the sky a day ago, and now the 2 right side motors wont spin/arm/anything :( cant wait to get home from work and test them! thank you! thank you!

[@brighb123]

You’re a legend Josh

[@MrAstrals]

This is a great idea, thanks for the tip. I'd like to add that the motor should not get hot if spun this way without any load. That would indicate some winding having short in it.

[@lostjohnny9000]

Love this hack Joshua, Many thanks for the always informative videos. These funky little brushless motors we use are also effective three phase alternators. So by connecting one directly to another back to back will allow the twisting of one motor to drive the next. Might not instantly determine a faulty motor winding on it's own without some fiddling but could be a quick way to compare a suspect motor to your "known good" motor out in the field.

[@andym5195]

great vid dude, never thought of doing that.you can also put a little bit of electrical tape on the thread of the motor to protect it

[@MrSabram07]

Okay Josh this was a good video I did learn something. I'm researching a problem with a drone I'm working on, at about mid-throttle, can't find a rhyme or reason, but it will fly and hover and then it seems that motor 1 will stutter and I think it's even reversing direction real quickly flipping and crashing to the ground. So I am going to replace the motor, I do have some extras but I wanted to troubleshoot and see what I can learn. I did run a bench test with beta flight and the motor is twitching and stopping.

[@xuxusito]

Congrats on 40K Subs!

[@mchaves7663]

Very interesting video. Congrats! Is there a way to fix a smoked motor?

[@JoshuaBardwell]

+M Chaves re wind it.

[@warbuzzard7167]

Very professional. I will use this technique to determine if I have a dead short in my new Turnigy SK3 motor, as last night I burned up my brand new Turnigy speed control.

[@primitivefpv6660]

If you have a dead short you will be able to see with a normal ohm meter. Test from each phase to case of motor you shold have infinate ohms. Your three motor leads are all connected to eachother inside the motor so you will see 0ohms

[@ryanr2n2yc]

i wanna have a few beers with you. you're a smart guy and i appreciate the videos, you've taught and helped me out quite a bit as i get into this hobby. thanks

[@QOSQualityofSpeed]

Well when a video is that useful I've got to say thank you. Yeah I really honestly no one else has given that kind of knowledge and I very much appreciate it I just wrecked my mini racer I guess toothpick the other day and it seems that one motor is not spinning properly. Now I have some ideas of how to check it to understand if it's the motor or the controller. Thanks again

[@rtkracht]

Dude... I learned something today!

[@ruddersidedown]

Josh, (6:38) was that you hinting of a party at your house this summer? I'll bring beer! Thank you for all your wonderful and very helpful videos.

[@MichelePlunkett]

Quick question After building a dslr 2 axis gimbal I plug in the battery nd the motors would not turn on and spin. the controlboard was blinking red. So I attempted to plug the control board to mpc whichit started smoking. My question is this: What happened? Did the motors fry too? The motors were a 5208 . The controlboard was a cheap bgc about $14.

[@chriscavill2015]

The measured voltage is the back EMF. It can be used to calculate the Kv of the motor. Rpm/(vAc*1.414*0.98) This will be a close value to actual motor Kv.

[@TransAm2k4]

using that calculation suggest the motor is actually ok then...

[@williamgleason7867]

When operated as a generator, there is no back emf only emf. Back emf is a characteristic of a motor not a generator. Where did the 0.98 come from in your equation?

[@chriscavill2015]

William Gleason the entire formula is used by the Heli guys to calculate rewound motor kV. They found small discrepancies between calculated and actual, hence the addition of the 0.98.

[@Fulminin]

Considering that you need a known rotational speed for this wouldn't it be easier just to measure the rpm of the motors using a tachometer then dividing that by the voltage minus loss due to the resistance of the motor.

[@fen1x591]

Heeeey Josh! I had one motor with a little bit of burned winding, that I could scrap of and cable then looks kind of nice, tested the motor with this method and everything seems to be fine, constant voltage with all motors. Does that mean that my motor is all right?

[@NoAgendaFPV]

Should be able to put the prop nut on and tighten the chuck on it to save the threads. Good video!

[@Migueldeservantes]

Very useful stuff, congrats on your 40K subscriptions..

[@RCinginSC]

I know this is an older vid but I actually do have a question. I have a 15000kv 1s motor that started twitching and stopping intermittently. Everything checks good electrically and physically. I'm not asking you to diagnose the problem since I simply replaced the motor, but in the vid you repeatedly said "something" may be wrong with the motor depending on the results. What exactly is "something" that can go wrong . When 3 phases are balanced, the output is within range, no physical damage and close inspection shows no internal damage, then what actually fails? This is the first motor that I couldn't find anything definitively wrong with it, yet it twitches and stops. Thx

[@JoshuaBardwell]

It's usually damaged winding or maybe bearing preventing the motor from spinning. A very precise resistance or inductance measure would be the proper way to test the motor, but it requires specialized equipment.

[@x-forcefpv9620]

You rock! I was wondering today how to test my motors. Thank you!

[@GarHarman]

Top quality info Joshua!

[@christopherwhull]

If anyone wants to go deeper with this testing lightly loading the motor might show other defects in the Voltage test with more fraction microamps of loading by a multimeter. I have put a 3.3K (5 W) load resistor across the multi meter inputs, a high impedance multi meter the test not load the motor/generator and a resistive loss from a partially nicked through coil will not show up in an unloaded test. Since the mounting screws contacting the coil are also a problem test with and without the screws. Turing the braking function in BEHELI to higher than stock on the ESC will also show off suspect motors with bad coils without props. I use $10 dollar motors since moving from buggies to drones and replace everything that does not sound, feel or react right immediately dump it. In the good old days we spent $80 on a brushed motor of the same output class so we used a ton of TLC, it was half as efficient also 8 times heaver. Good riddance. Newer, Better, Cheaper...on backorder.

[@HighVoltageProjects]

Great video (as usual) I'm sure this will hell lots of people out.

[@RawTopShot]

" a generator - like when you're camping " 😂ROFL I learned something today AND got a belly laugh. Thankyou Joshua 🏆

[@proz71ful19]

Believe that is called glamping hahaha

[@nightnoodlespeedruns]

Hey Josh! So i kind of have a Problem... my Motors are broken but i can't figure out what motor it is. I want to buy new motors and install them but i don't know which i need so i wanted to ask you how i can find out.

[@robcarnaroli269]

Looking forward to trying this on a bad BabyHawk motor I have. I was getting a slightly lower resistance reading on one phase. Like you said though my meter cost $60 so no supper low readings. As for the motor, it would twitch instead of spin. Happened out of the blue after flying a dozen flights. Replaced it and it's flying great again. BTW thanks for the review of the BH. I love it for practicing. Even 3D printed antenna mounts for it.

[@Robnoxious77]

Rob Carnaroli I had a racerstar motor do that to me a couple weeks ago. The motor basically shorted on one phase, the effect being the motor would twitch then stop, twitch then stop, even under high throttle settings. This failure happened mid flight, about 10m off the ground. Dam thing flipped upside down and drove at full speed straight into the ground. Completely destroyed a go pro, the vtx antenna and split the frame into three parts lol, at least the battery survived! ah the fun we have haha

[@robcarnaroli269]

Ouch, ya I can't complain about a $10 motor :-)

[@willsoper4968]

Great video. Thanks. Any reason why I can't run this test while the motor is wired to the ESC? Obviously without a battery installed, can I take the reading at the PCB points?

[@JoshuaBardwell]

That would probably be fine but I haven't personally verified it.

[@rhielfpv4371]

I am always follow your good tips in this hobby and its become more interesting...I am still using conventional method to ensure the bad motor by feeling the magnetism when i turning the motor by hand. If its same feel when turn it with two motor wires jumper then it confirm the windings was internal short..

[@petertothRC-FPV]

Great tip.I have wanted to use another motor on my ebike to charge my battery as i ride.But adding more weight and stuff maybe just keeping it simple is best.

[@stranger534]

just don't use another motor, make a mechanism to switch the motor from the powering circuit to a charging circuit. Using a two position switch, you could select between having the motor connected to your speed control circuit or connecting the leads to a charging circuit for regenerative braking and charging of the battery such as when you're going down a hill or you want a workout.

[@lokisdream8438]

Awesome as usual JB

[@rays8935]

Brilliant video again . Thanks

[@matheuswronski]

maybe the voltage output it's not matching with the kv because you're measuring ac voltage. the multimeter divides it by square root of 2. if you multiply 0,75 times square root of 2, you get approximated 1 volt, that matches with the kv of the motor. it's just an idea. correct me if I am wrong.

[@JoshuaBardwell]

I think you are right.

[@Sytrag]

but Joshua is using the AC scale meter already and not the DC scale meter, so there's no need to do the calculation? Maybe the reason for discepancy is that regular multimeter only measure sine wave AC and not the type of AC wave form produced in this test?

[@ol-man-duffyj688]

Thanks Josh, very cool and helpful.

[@TheCatsa]

Another great video from the great JB. Thanks brutha!

[@PerBuch]

You need to know what you are messuring. Does that crappy meter messure rms in ac ? and can it do it at the freq you are messuring ? The kv rating for the motor are relatet to the dc voltage, and that determines the peak ac voltage the esc can output.

[@pontiac455judge]

I have been using Hz to test motors. I'll try voltage and see if there is a difference.

[@JoshuaBardwell]

Hz should depend on the rpm you spin the motor at. Unless you have a way of spinning the motor at a precise RPM I don't think Hz is as useful.

[@1337flite]

+Joshua Bardwell what do you use as a camera in these talk to camera videos - is it a laptop camera or do you have some kingd of "real" camera set up? Any chance of a quick look at your talk to camera studio set up? Thanks for all your work.

[@JoshuaBardwell]

My webcam is: amzn.to/2rZtWTV That one is a freaking beast and amazing for the price. I have a 2nd one that I take on the road just because it's so cheap. I also sometimes use it as a 2nd camera on a particularly busy shoot. The overall image quality is good but what really makes it is the Logitech camera app you can install, which gives full manual control over exposure, etc. which means I can tweak the image to get the look I want out of the camera for minimal post-processing. This is especially helpful when I am in bad lighting conditions. My bench cam is: amzn.to/2rKm5pb It's also great for the price. Has microphone input. Decent manual controls (white balance, exposure). Good zoom, although I sometimes wish it had a little more macro capability. I intended to use this camera more widely than I actually do, in large part because the C920 turned out to be so good. This camera would not be good for vlog-style shooting because it does not have a wide-angle lens. Here's one more little must-have: amzn.to/2tCseEU That grey-card will let you get correct white balance and exposure out of nearly any lighting condition. Very useful when I am in a hotel room with god knows what color lighting. I also carry with me two full-spectrum 100W LED bulbs when I travel, so that I can replace two bulbs in the hotel room if they are particularly atrocious. MANDATORY DISCLAIMER that those links are affiliate links and I get a small commission if you use them.

[@kraigvanderwyk2443]

I have 3 identical motors and one odd ball, although it’s is same size and kv. I’m using individual ESC ‘s. The odd motor keeps burning ESC. Would the fc cause the ESC to burn if all motors were not identical? Or simply the 4th odd motor is bad?

[@elliotfpv2645]

I like your videos so much I'm now using my phone data up to watch this!

[@saberrayed]

Is it possible while the quadcopter is in the air and motors are spinning rapily then connect another set of wires or adding a small charger to the battery to have infinite energy?

[@hillbillyfpv1]

Hey Josh.. I know this is a tad off subject but don’t know how else to get in touch.. I had a recent crash that I’m just realizing a bell could be slightly bent on one motor... if it was to not be able to reach the RPM it once did, will the pid controller slow the other motors to match power? It has lost the punch it once had. I have parked it and ordered a new motor.. just wondering about the power decrease.....

[@JoshuaBardwell]

Yes, that's right. The other motors will have to slow down to match the weakest one. But you're also likely to smoke one or more motors due to increased vibration. If you've got that much damage to one motor, it's time to replace it.

[@hillbillyfpv1]

You’re quick! Lol You have many vids to sift through. Thank you! The Vortex 250 is parked.. motor ordered and hopefully it’s the only damage.

[@daveherron]

I was big into car audio 15 or so years ago. I didnt realize at the time the amplifiers powered by DC actually put out AC to the speakers. I never actually tried it but supposedly if you had a subwoofer that can handle enough power, you could plug it directly into an AC outlet. Since it runs 60Hz, it would give your sub a big test haha.

[@dronetrooperfpv7810]

In almost 10 years of using brushless motors, I smoke an almost new motor today. It was twiching while the quad was armed. I plugged it into Raceflight to see what the issue was and smoke started coming from the motor. Does this mean it is toast? Do you think an ESC is the problem?

[@JoshuaBardwell]

Yes the motor is toast. Don't fly a motor once it smokes. Even if it seems to fly, it can't be trusted. The ESC could be the problem. If you arm the quad and the motor starts twitching and not spinning, disarm immediately as the motor may be about to fry. It could be that the motor was damaged and as a result, it smoked. It could be that the ESC was damaged, and it smoked the motor. The only way to tell for sure is to install a new motor and see if it spins or twitches. USE A SMOKE STOPPER LIGHT BULB!!! It will protect you from smoking. If the motor twitches, the ESC is bad.

[@lazyboy1871]

Ive had a quick look through the comments but couldnt find the answer im looking for, is it safe to test the motors while on a quad as they will be generating electricity? Or should you desolder them from the ESC's to test? Many thanks for the great vids, couldnt navigate this hobby without you!

[@TheLightningStalker]

This is how active braking works. The ESC stops the PWM and the motor keeps spinning and generating AC. Then the ESC switches all 3 phases to either - or +, effectively shorting them out. This puts a heavy electrical load on the AC being generated by the motor. The electrical load is translated into a mechanical load by the motor and causes it to quickly slow down. Just try spinning a motor with your fingers and then try spinning it again with the wires shorted.

[@sennahtsivqlle]

Thanks for the great info

[@ericimtf]

I use LC meter to measure motor. They should have same inductance value.

[@JoshuaBardwell]

Yup. If you have an LC meter that is a great way to do it. If you don't have an LC meter this is a decent workaround.

[@quetiano]

Thank you for the awesome and informative video! I have a question regarding repairing a motor, for example, lets say that a motor voltage on one pair of the motor wires are different from the other two pairs to be tested, can that brushless motor be repaired ? Generally, can all brushless motors that do not beep including not spinning when powered on, be repaired ? Reason is, I am building my first quad, using an apm 2.6. Not sure what caused this, perhaps a wrong connection method of power to the apm, but all four motors beeped, turned on, and when applying throttle, two had some issues spinning, like twitching, the other two spun up when applying full throttle for about 2 seconds, after the second or third try however, none of the four brand new motors beeped when switched on, and none spun up when trying to use the trim trick. I did not calibrate the escs since the motors gave up. I disconnected all four motors, bypassed the apm, and tested each motor, which did not work. I had a new motor stored away, which I tested without using the apm, and it worked on all four esc's, so it was definitely the four motors that seemed to have given up. I havent tried this trick in your video above as yet, but I will do so very soon, perhaps later today (03 September 2019) So if I find a problem with all four motors, can they actually be repaired ?

[@JoshuaBardwell]

You can re wind the motor but it's a lot of labor and may not be worth the hassle.

[@quetiano]

@@JoshuaBardwell Wow, thank you for the prompt reply, that was excellent ! I have updated my reply above, please read it again if you dont mind... The motors are XXD A2212 1000KV , from banggood, www.banggood.com/Wholesale-XXD-A2212-KV1000-Brushless-Motor-H363-For-RC-Airplane-Quadcopter-p-57432.html?rmmds=myorder&cur_warehouse=CN 1. What do you think that might have caused that problem Mr. Bardwell , so I wont make that mistake again ? 2. Since I have five brand new motors, one gave up as well during testing, do you think its worth repairing all five ?

[@KrotowX]

Nice demonstration of electric generator :) Also recuperation brakes in trains, trams and electrical cars are working in similar way, converting vehicle moving energy back to electricity which goes back to power line or charge the car battery. Even drill is not needed if you manage to fix motor good enough to rotate motor bell with hand a couple of seconds to notice voltage raising. Would be cool to use autorotation to charge quad battery on flips and power loops :)

[@JoshuaBardwell]

The drill is needed to spin the motor at a smooth and consistent rpm. Otherwise voltage will fluctuate.

[@KrotowX]

Which doesn't deny the fact that motor wouldn't generate any voltage between teared winding not by rotating it with drill nor hand.

[@HighTideFPV]

I have a question. I had a crash last week and damaged an esc. I had another but it wasn't the same brand or had the upgraded firmware. It was a behi-s. Anyways towards the end of the day when I spun the motors by hand that one I had changed(esc) , the motor wouldn't spin as well as the others, felt like esc braking with the battery plugged unarmed. When I desoldered the esc from the motor, it spun fine. Was it because of the electricity it was creating giving it active braking?

[@JoshuaBardwell]

Something like that, yes. kzbin.info/www/bejne/iJKmm32YeqdjbZo

[@donankeny5013]

Could be the electronic difference of the esc's to each other like the odd one using larger filter caps or different fet gate arrangement, etc.

[@InFrontOfYourBack1]

This is great stuff. I definitely learned something today!

[@rcwck]

If you do have a IR meter do you have to disconnect the motor from the esc to an accurate comparison reading for the motor windings?

[@JoshuaBardwell]

I don't know about that for sure, but for measuring things like capacitance and inductance, I think you usually want the component separate from the circuit.

[@thfpv4974]

Thanks !!! I'll try that out💯

[@DangerDavefpv]

im so lost ive got three esc that has randomly flip of death in air and there all used with zmx finx40 2.6 motors on 4s and they all have blown a fet (mosfet) what could cause this? ive got ur version 1.2 jb f4 f.c with capacitors wired directly to the esc power pads but i dont use those for esc because ive been using 4.1 esc and i just wire my signal wires to the f.c and i got lipo wired to esc input then i jump a set of wires from there to the flight controller. should i just toss the motors out? they was new

[@propsoff]

Bardwell, your Amazon link to the tachometer needs updated... Great info! Thanks.. ScooterPie,

[@globaldesi2956]

Hi Josh , i just built my 1st zmr250 with racerstar2300kv motor+little bee 20amps ESC and naze32 but i have 4200mah 4cell battery is it safe to use it or it will blow my ESC and motor

[@JoshuaBardwell]

+indian quadcopter things it's safe to use. But it's way too big and heavy. The quad will fly terrible.

[@QuadView]

Excellent. I would like to make a windmill with an old motor for my son. Cool.

[@xerovolume3321]

1:45 Correct me if I'm wrong here, but I thought these were "brushless DC motors" not AC motors... I thought the ESC is producing 3 separate square DC waves, not AC sinusoidal waves (which would have to change polarity to be considered AC.) Is this correct?

[@JoshuaBardwell]

The ESC drives the motor with square waves. But the signal that comes out of the motor when it's spun is not a square wave. kzbin.info/www/bejne/o5CZf5WkgbuCaa8

[@andresmauriciozuluagaboter4196]

Great video. What happened if my motor only have two wires?

[@JoshuaBardwell]

then it's not a brushless motor and this won't work

[@briandias1082]

I have 3 racing quads and all three have one motor that won't spin . I bought them already built and they are known brands ??

[@romulan32]

Does your multi meter have to have a lower setting other than 200 v

[@JoshuaBardwell]

200v would be the max. You can always use lower voltage no problem.

[@juggalizzle75]

I always fully insert my shaft thank you. Thanks for this. Not everyone understands electricity flows two ways. You could do the math beforehand and figure out exactly what voltage it would take to spin the motor at a given rpm.

[@rcwck]

Can you do a similar motor health comparison test while the motors are connected to the esc's and applying the volt meter to the pos/neg esc pads?

[@die_hertz]

No, you can't

[@JP-mv6kk]

Mr Bardwell, whats your take on reversing the standard Betaflight motor spin directions? Example: instead of having front right motor spinning anti-clockwise, have it spin clockwise. (swap props accordingly and do this for all motors) how does this effect the flight characteristics?

[@ZeroFPV]

Goto Betaflight CLI set yaw_motor_direction = -1 save + reverse all motor directions in BLHeli Suite (cw -> ccw, ccw -> cw) Done... It won't change flight characteristics much. Some say it would be more efficient. However it helps to keep your camera lens cleaner...

[@JoshuaBardwell]

The main advantage in my opinion is that you throw grass into your FC stack vs. your camera lens. Personally though I don't find it difficult to clean my camera lens. Another advantage some have said is that when you fly into a branch, the props push the branch out vs. pulling it in. As far as flight characteristics go, the majority of people I have talked to say no detectable difference, although a few people say there is a night-and-day difference. Micro pilots especially seem to like this approach. I don't use it personally because I'm not sold on the benefits and I am too lazy to reverse all my quads.

[@zanekelley5351]

Quick follow up question to that JB, what about making a pusher style mini quad? would there be any advantage? props on upside down etc, figured you would be the person to ask

[@ZeroFPV]

In the normal config some of the air your propellers is moving is blocked by the arms of your frame. This air is reflected by the arm and will work like a tiny brake (thrust vectoring). This also is causing some oscillation.

[@williamgleason7867]

Your original premise to verify the health of a static motor is valid although things may change when it it becomes dynamic. Be cautious trying to determine the motor velocity constant with a multimeter. A multimeter measures AC as RMS and the motor velocity constant is by definition determined using peak voltage. When using constants such as 0.707 and 1.414 to determine peak voltage you are assuming that the output waveform is perfectly sinusoidal, which is not likely. Any variations in the waveform will give a different RMS value. To determine the motor velocity constant it would be better to use an oscilloscope to directly measure the peak voltage. The multimeter works fine to determine the rough health of the motor as you originally stated.

[@fdylanyall]

I would imagine that the output waveform of a driven BLDC motor would be fairly sinusoidal, however the input from an ESC would almost certainly be more trapezoidal. It would be interesting to see Mr Bardwell's test performed with an oscilloscope.

[@manuelpellizzari8540]

Hi, about this magic incredible thing comment you make towards the end, you could have also related it with active braking : which is in fact converting this mechanical energy of the spinning prop+bell and feeding it back as electrical energy to the esc/pdb (and uses the same idea of generator).

[@senseisecurityschool9337]

Great (old) video. One reason the voltage output doesn't match the measured RPM* KV is because the RPM was measured without the motor attached. Attaching a load is going to slow the drill a bit.

[@RustProof1]

Any chance you could measure the amps? I'm trying to get my head around voltage spikes during regen/breaking. I have capacitors installed and it works great but the voltage generation just seems so small yet their effects travel through out the electrical system.

[@RustProof1]

Scratch that. I went back and watched your capacitor video (which I had already liked "score") and you said that Quad Mcfly said that he had measured up to 4amp of regeneration..... Thanks again.

[@shirdiali]

great tip....thanks

[@hockeyguy820]

It might be interesting to note that when you spin a motor to make it act like a generator, the greater an electrical load you place on the input (now output) wires the harder it becomes to turn the motor. This is because you are now dissipating electrical power (voltage times current) and this power is being converted from mechanical energy. The prop brake setting on your ESC uses this principle. It places a low resistance across the motor windings when throttle is a zero, slowing the prop down.

[@pauljohnson7538]

I worked at a motor rebuilding company and we built 2 10,000 hp D.C. motors for a gold mine elevator and to test them we coupled them together and ran them with a resistor bank on one at a time the amps through the resistor bank can be calculated into horsepower so we proved to the customer each one would produce the 10,000hp

[@michaelinmotion]

You could also use a Dremel, because on most Dremels you have to toggle a very specific speed setting, unlike drills that have a pull trigger. But that was neat! Thanks!

[@JoshuaBardwell]

Yeah but a Dremel spins at much higher rpm which could be a problem for your hands. Not the motor though.

[@GUILLERMO.NESPOlO]

this one was a nice one

[@bekins47]

copy that. mind blown. thank YOU

[@yokonunz]

Hi Joshua. Does ever happened to you that a new esc smoke an engine just right after connecting the battery?

[@JoshuaBardwell]

Only if I soldered it wrong. Always use a smoke stopper when first powering up.

[@yokonunz]

Joshua Bardwell I tried an hobbywing xrotor 20a with BLHeli in it and it smoked to engines. the beeps on boot started correctly then became loud and distorted then smoke came out from both motors. both 2300kv but from different manufacturer. one racestar and one emax. thanks for the suggestion for the smoke stopper