How to Measure Horse Power for Any Electric Motor: (

How to build and use a dynamometer for measuring Horse power in the home shop. Links to download models and parts list below.
How to measure the mechanical power of an electric motor.
If you want to chip in a few bucks to support these projects, please visit my Patreon page.
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My website www.jeremyfielding.com
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Notes:
I did not add quite as much detail as I would with paid plans but hey... you are definitely getting your monies worth!
Link to download files.
github.com/jen...
Other references.
Matthias Wandel's Channel
/ matthiaswandel
Building my variable DC power supply
• Building A Variable DC...
Amazon affiliate links
DC power supply: amzn.to/2wG9qe8
AC powermeter: amzn.to/2Tc7y4x
DC powermeter: amzn.to/2TbaJZU
Scale-Load cell: amzn.to/2wxRmmf
RPM-Tachometer: amzn.to/32j4Ii8
Technical corrections
1. I discuss changing the bearing to allow higher speeds of the test motor. However, the rotor of your braking motor is designed/balanced for a specific rpm. It might vibrate or even self destruct if spun at higher speeds. My motor has survived several test at 21k for an up coming video, but that certainly won't apply to all motors used for this.

[@TrueHolarctic]

This chanel is like aplied science, but for motors

[@throngcleaver]

I ordered a dynamometer from eBay, but they sent me a dinomometer, which measures the strength of ancient reptiles. Great video, Jeremy!

[@JillofAllTrades2]

throngcleaver 😱🤪😆

[@matthiaswandel]

If you use that induction motor at high torque low RPMs for a long time, the rotor will overheat. Rotor induced power is a function of torque, but cooling is a function of RPM. It might be better to use an open framed motor for the brake, so that you can blow air through it. Also, a 1800 RPM motor may not be well enough balanced to run at 10,000 rpm as a brake. You need to use a motor that is at least close to the rated torque and RPM of the driving motor for the braking motor.

[@Jeremy_Fielding]

I agree that using motors similar in RPM and torque would be ideal for several reasons. But, for DIY level testing I think that might be difficult to have. I will add a note to the description about the rotor not being balanced for high rpm though. My motor has survived several test at 21k already for an up coming video, but that certainly won't apply to all motors used for this.

[@gmack4097]

@@Jeremy_Fielding Would a water cooled CNC type HF Spindle motor make a better brake for high speed motors? Drive one phase with a rectified VARIAC output?

[@AccidentalScience]

@@xicath the pulley reduces rpm at its output (i.e., larger pulley attached to a smaller one on the motor's shaft) so the motor spins at the same speed and gives the same torque (thus the same power).

[@cduemig1]

@@Jeremy_Fielding Holy cow. I’ve always heard not to exceed 10,000 rpm on components not balanced for high speed operations. I was going to post the same thing about spinning an induction motor past 10k. The rotor windings usually aren’t secured well enough and fly apart crashing into the stator windings. With that much inertia spinning at 21k that would not be a failure I’d like to be sitting two feet away from.

[@mckenziekeith7434]

Some induction motors (usually more expensive ones) have a published maximum safe speed. I have never seen a generic off-the-shelf safe speed higher than 5400 RPM. But I suppose I have not done an exhaustive search either. I would expect that the motors which do not specify max speed are actually even less reliable than the ones who have specified it.

[@jwhite1016aol]

That was some nice motor label editing cuts.. the extra effort is not wasted on me cause I noticed.

[@JillofAllTrades2]

Jameson White I noticed this too. He does an OUTSTANDING job of his videos, doesn’t he!

[@jwhite1016aol]

@@JillofAllTrades2 always

[@AustrianAnarchy]

You have one of the most awesome names for an electric motor guy!

[@jlibb099]

Jeremy, good to see you posting again.

[@JillofAllTrades2]

Jeff Libby It’s def. a challenge to do and to show. It takes a lot of time to get a quality video together. That’s why mine are still on my phone (you know, that sophisticated piece of equipment that’s turned into an everything for the regular Jill 🤫).

[@cafn8ed74]

If there is anyone else on KZbin presenting content like this in such an understandable way I certainly haven't found it. Thanks for all you do!

[@afonsoczernin3615]

Hi, loved your video thanks a lot! I'm an electrical engineer working in the field of inductions motors and I would like to leave just one remark on the service factor: Assuming an operation duty cycle of S1 (continuous operation) SF 1.00 means that the motor can run undefinetly at the rated power without overheating. SF 1.15 is exactly the same but at 115% of the rated power. Th

[@calebbadger]

We have a commercial version of this at work. We build motor controllers and we will characterize the motors our customers use and build the controller to work with them. I was surprised at how intuitive these are and I'm impressed that you made one.

[@Taran72]

What a great video!! Thank you for sharing. I have been needing a home made dynamometer. :)

[@DracoOmnia]

Story of my life, "I did think about buying Z... But when I saw the price I immediately started thinking about a DIY option"

[@JillofAllTrades2]

Same here! Do you also have many projects in progress with all the materials/components? I hit a road block and at the same time seem to get sidetracked by something else “urgent.” It end up being challenging to get back to the bloody project to finish it. So ... got a few of those work-in-progress DIY projects lying around 🙄🤪. Husband’s wonderful at indulging me, but being stymied and stopping is driving me nuts! (I HAVE been successful at completing many DIY projects, but all I see are the ones I HAVEN’T completed). 🧐

[@Somebody3928]

the same is often true for software

[@bagusahmadfauzi2624]

Dynamo power full

[@gregglasgow9432]

Your knowledge amazes me. What a joy you are to watch and learn from. Thank you

[@gregbrooke3945]

FYI, Magtrol dynamometers use a similar torque transducer setup. Theirs is a calibrated lever with a strain gauge to measure deflection. Additional I tried this into a pre-DOS computer system and wrote all the software enabling us to have a graphic and tabulated measured and calculated values. I've played with arduino, interfacing should not be a big problem.

[@MarkMcCluney]

Magnificent. The moment of delight when you suspected the clutch and wanted to investigate was so inspiring. Your attitude is what so many young folks have educated out of them when they study science and engineering at the most formal level. I think it's appropriate to say 'more power to you Jeremy!'

[@JillofAllTrades2]

Inquiring minds! (Because inquiring minds want to know ... or is that copyrighted?)

[@Tryin2FlyII]

You Sir are a ABSOLUTE GENIUS!! In my eyes Thanks for sharing your knowledge!!!

[@dr__mortal4666]

Currently, I am using Actual Dynamometer for R&d purpose of Induction motor, But Thanks to you about this DIY, that will help lot more for me. So Good work & thanks

[@Blackmage50]

That was impressive! Hats off to you. My dads a millwright and they do motor alignment all the time. Quite a lot more to precision motor alignment than most folks think. It would be fun to have this in my shop to test the motors I come across and use.

[@brettkarling5671]

I love how excited you get over the work you do, brings me joy watching you enjoy your work!

[@onenewworldmonkey]

I seriously use your channel all the time. You are the best at understanding and teaching everyday electronics. YOU DA MAN. Thanks for your help.

[@bradshaw106]

Great video! I have been planning on building one of these, but using a car alternator with adjustable field. I like your design

[@azlandpilotcar4450]

Good project! A couple thoughts: 1. Gearing your brake up with a belt drive could extend the range of measurement. 2. The rowing machine and/or a treadmill electronics display contain sensors and some forms of speed, distance, and power measurement that would could help you get some digital instrumentation for the dynamometer. Some that I've used displayed Kw and rpm.

[@scroungasworkshop4663]

Thanks Jeremy, now I have two options to measure the unknown torque of my electric motors. The old way that I have been using for years and has served me well which is put on a leather glove and grab the spinning shaft or send them to you cause I didn’t understand a word of that. Cheers Stuart 🇦🇺

[@JillofAllTrades2]

Stuart G. Australia. 🤣 Yeh, me either mate, but what kept me watching was his presentation and clear communication in such a pleasant voice. And! I appreciated there’s no fluff and no flappin’ his gob just to extend his time in front of the camera, like in some other KZbinrs’ videos. (Note to self: Do NOT babble on when you get to your own videos; you know, the ones that are still waiting for you on your bloody phone, buggerit.)

[@samhziegler]

I love how often your channel comes up, as I puzzle my way through whichever technical/electronic/engineering problem is holding up a project at that moment. Cheers mate

[@joelwatts9042]

Very cool. Don't think I'll copy it, but good knowledge to have. Thanks

[@MindMeetMaker]

When you 3d print things think about the direction of your layer lines, layer adhesion plays a big part of the part strength. Great video like your approach.

[@Jeremy_Fielding]

Interesting thought... This is complicated by also wanting to avoid over hangs. I guess you can always print support structures... or try to design with both in mind at the start.

[@MindMeetMaker]

@@Jeremy_Fielding its always a problem, the easiest way to print an object may not be the strongest, so support structures are sometimes the only way to get it done but thinking about layer adhesion will help make your decision when designing at part for strength. 👍

[@TestSpaceMonkey]

Another way around this is to separate the print into component parts. Ex.: print each tooth of the coupling so layers run axially and put a collar around them (printed, hose clamp or snug-fitting metal tube/pipe). Each tooth part will need to interlock with the next under the collar to prevent shearing between them. Modelled up a quick 4 tooth example in FreeCAD (well, 1/4 of a 4 tooth set): www.dropbox.com/sh/r194qv274800u67/AAAbyd3rdz7aFdtCWIpbD4XHa?dl=0

[@destructionator17]

Interesting you did this video today! My furnace's blower motor is acting up, but the label on it is totally unreadable and the furnace make has no info, so I can't confirm the correct replacement part. I thought about just measuring it while running but couldn't get a proper test rig... your ideas might just be what I need! Though, on the other hand, my furnace is almost 30 years old, so I think I want to put a whole new one in anyway.

[@horacerumpole6912]

Take your motor to an electric motor shop, they can tell you what you need for a replacement. These motors are standardized-

[@n1zw]

Your channel is by far my favorite when it comes to salvaging parts that can be repurposed for all sorts of homemade projects. Keep up the great work, please.

[@Kevin-gx8lc]

Brilliant Jeremy! Thanks for sharing... I always learn things from you! Top Man! Greetings from Southport UK.

[@r410a6]

I got to say that your videos are a real encouragment.Tbh I dont have an engineering mind I'm not good at these stuff but your videos are really helpful.Keep doing what your doing!!!

[@danieledick2678]

This is so cool! I run a hobby rewind shop and was trying to come up with a way to load test my motors when I’m done with them. Thank you so much for sharing!

[@boltonky]

I really enjoy your videos, more so at the innovations and thought that goes into your projects. Keeps me wanting to keep doing more even when limited :)

[@clubpasser123454321]

Thankyou! You've cleared up a few long standing questions I've had about how to test electric motors.

[@MT_T991]

Your videos are truly fantastic, you are a natural presenter clear and concise. And a brilliant roll model

[@vennic]

Looks like the donut magnet and machine screw did the trick? EDIT: It's great in this video to see the culmination of so many of your home builds come together to make this project happen

[@Jeremy_Fielding]

Definitely 😀

[@MR-uk7iy]

If only I would have had you as a teacher, your videos are amazing man, both me and my brother are super entertained and educated by your stuff!

[@Tools-Tested]

Nice video, I am working on a hydraulic dyno right now. Just because I know way more about hydraulics and I want to hold the load on the motor for about 30mins, I was worried about using a motor as a brake for a long period of time because of heat. Same concept I just need to get a base line HP for the correction factor because of the efficiency (heat loss) of the system which should be about 80%.

[@geraldstephens8791]

Fantastic as usual! Glad you're back.

[@theupscriber65]

LOVE THIS! I built a desktop dyno in labs for a Mechanical Engineering program. We used a hydraulic pump and pressure gage to measure power. But looking at your setup, I think you could make it even more simple by mounting a rotor that is spun by the motor you are testing and gradually increasing clamping force through a caliper with your rod mounted to it. Btw, you may check out a laser RPM gage instead of the prox proxy sensor.

[@CaseyConnor]

Just stripped down my first treadmill thanks to your suggestions. Got a 3HP burly-ass variable speed motor and all the other goodies. Going to use it to make an over-powered apple grinder. :-)

[@JillofAllTrades2]

Casey Connor Hot dog, apple sauce! 👍🏻 🎉🤓

[@dtnicholls1]

For the coupling look holset couplings. Might not be so great for the universals but will be fine for the induction motors. You could also use a treadmill motor (as a generator) with a rheostat on it. Measure rpm, voltage and current. Start at no load and wind down the resistance till you reach the right RPM. From there you can calculate hp and torque given estimates for slip, efficiency etc based on motor design (errors that are already inherent in the current design). Should be much simpler to build, just a little care required to plot the efficiency of it at various rpm to get good accuracy.

[@elfpimp1]

So good to see a new video. I'm working on the flip workbench right now, lol..

[@nikolaradakovic5050]

I like so much your channel :) , you are a real artist Jeremy

[@joemwiti2316]

Great job, your videos are usually amazing. You take your time to explain in detail, keep up the great work mate.

[@garyha2650]

Thank you Jeremy, I learned a lot

[@Embeddedtronics]

Thank you. I wanted to make a test rig to measure stepper motors torque vs rpm curves. I know now what to do. Much appreciated.

[@DonaldSmith1]

Great video, thanks. I have always heard that click and now know what it's all about. So simple and functional. Thanks again

[@briannelson605]

Good to see a new video from you!

[@appleorange7547]

Hey Jeremy, big fan of your videos! I have a suggestion! When 3D printing stuff like those couplers, the orientation of those print layers will change it’s strength in the plane the load would be applied. So, instead of printing where the torsional shear stress would be maximum along the same plane as the layer by layer print orientation, a simple 90 degree rotation (or printing it on its side) would significantly increase its strength! Also, annealing the PETG for this application would help too! You may have a little warping from the heat but it’ll help add to the overall strength!

[@sandotrinistories.7820]

I'm still trying to set up my shop to do some of the things you are doing Jeremy. Keep posting, I'll be done soon. Thanks.

[@KowboyUSA]

Excellent information. Thanks, Jeremy!

[@davidchristensen2970]

Very nice presentation.

[@kn4dgs]

Good stuff! I plan to build one once my next shop is finished. Thanks, Jeremy.

[@amirouw]

Nice video it was ... Ammazing work . But im looking for a missing part i think should be included in the video and thats how you calibrate your measuring instrument you made.... Every measuring device every gauge needs to be calibrated ....overall It was nice though.

[@oliverdouglas9887]

This is awesome! I'm trying to design my own dyno for motor controller projects, but I don't know the mechanical stuff so well. The part I have been most unsure of is mounting the test motor in a way that provides good alignment and works for test motors of various sizes and shapes. I would be really interested to hear you expand on your experience with that and see how you set up a new motor. It looks like you have to machine a custom bracket to bolt the faceplate of the test motor to the aluminum bar. I'm thinking about trying it with wood or 3D printed plastic (I don't have access to proper tools for working with metal). I wonder how much speed and power is possible with those materials. If that doesn't work out, a belt or chain drive seems like a good alternative.

[@jacklarson6281]

Heya Jeremy, It's been a while since I've checked in on your channel. its soo good to see that your still teaching and making cool stuff. I may have said it before, but if I had had a shop teacher like you, id probably be designing and fabricating parts for the space shuttle now... :-)

[@bradjohnson6919]

I love it, clean, simple, effective. Great build.

[@Rob-Heaston]

The strength of that petg coupler would increase pretty significantly if you print it at a 90 degree orientation from how you printed it. The print lines are weaker so if you print it in the orientation where the print lines are perpendicular instead of parallel to the rotation it'll be much stronger.

[@ImolaS3]

Love it!! Very cool and not something I thought of as a brake despite being an electromechanical design engineer! Doh :). By the way, you don't mean centrifugal force, it is an imaginary force that opposes centripetal force, which is the force that makes your magnet fly off

[@ComplexOne]

i was tired ,sleepy and just about to shut down my computer for the night until i seen this channel..

[@ericklinefelter5139]

Excellent video, Thanks!!

[@bro-shamsulnubairi8689]

thank you so much for the video.... its help a lot

[@gassanali8667]

it's been a while... missed your videos

[@rail00]

Wow. Great stuff. I find electric motors so fascinating.

[@abitoffcenter383]

GREAT to see ya Jeremy! Great info, Thank You Sir

[@curvs4me]

That is brilliant! Thank you

[@stevewhite6252]

If your motor lists the voltage and current this will give you a very close approximation to the power. Just use 746 watts per HP.

[@Jeremy_Fielding]

You don’t know the efficiency. Some motors are 80-85% (that’s common for induction motors) to universal motors at less than 50%. That number doesn’t tell you enough.

[@nicholassereno1315]

Very cool dyno! Looking to do something similar for small gas engines!

[@mckenziekeith7434]

Might be overkill but you could use a VFD to control the load motor. You would need to add the brake resistor to the vfd. Without the brake resistor, the DC-link voltage will get too high and it will shut down. Not all VFD's support brake resistors but quite a few do.

[@tonyhill8300]

nice bit of work

[@joeszabo4237]

You are a very kind man Jeremy! Cool video too!!

[@douglaskim6611]

Jeremy, good to see you again.

[@sekolahonlineteknikotomotif]

That's enough! I subscribed!

[@francispointofview7578]

I always learn so much from your videos Jeremy. Thanks for making great content!

[@Modna89]

Now you need an arduino in there recording the torque and RPM. Then have a button to log the data into a CSV file and log every 50 or 100 RPM through the range of the motors speed. Boom: Horsepower Curve!

[@JillofAllTrades2]

Modna89 🧐

[@DavidLindes]

Did you watch through 14:17 and beyond? :)

[@mxcollin95]

Love your motor test setup.

[@zfotoguy71]

If you went the route of a toothed belt, could you then use two different sized pulleys so your braking motor is half the RPM and still get accurate measurements? Could be an answer to the higher speed motors. Thanks for another great video.

[@vennic]

Or maybe a chain or gears? Would a belt have some compliance that would affect the reading? What about some sort of centrifugal clutch mechanism?

[@txkflier]

Great job, Jeremy. I'll check out some more of your videos. Thanks!

[@garagemonkeysan]

Nice video. Great engineering. Mahalo for sharing! : )

[@hgbugalou]

You are doing great work with all this knowledge sharing. When the apocalypse comes all us enginerding types need to a meet somewhere to restart society.

[@JillofAllTrades2]

Michael O 😱👍🏻😆

[@jacobsvatek7642]

Hi Jeremy. Love the video. I was hoping you could shed some light on how the calculations are made from the induction motor acting as a brake. How do you know the power required by the induction motor and how does that translate to the output torque?

[@bafa_tents_services]

A very good setup I love it and I love what you are doing ❤️

[@user-tq4tb8pi4s]

Good day sir, Where did you dump the generated electricity because the motor will act now as a generator. Can you show also how the wiring is done. Your response will be highly appreciated as I am working with same project for my undergraduate final year project . Thank you so much sir. Respectfully, Romeo

[@toms4123]

Nice project.

[@osgeld]

on your printed parts, I don't know if it would be any stronger but it looked like you printed the cylinder from bottom to top, which makes the force it can take dependent on layer adhesion, try it laying on its side, even if its the same strength it would twist then snap like a screw head rather than explode

[@tunckuyel]

If you do it with arduino or something like that you will need only arduino and a3144 hall sensor. You can see all data in serial monitor of arduino on laptop screen. And for scaling torque with a scale module. You have to use micros/millis and interrupt functions for rpm. I am trying something like that for my old vw t25 van. And i research for like 3 months. If you like ready to use codes for rpm i will share harvested codes with you :)

[@lloydbaker7099]

You always teach me so much

[@joecool5034]

Great video as always. Thank you

[@abdabzeebop2]

Nice intuitive way to build a dyno. So you get the test motor up to its rated speed, progressively add braking torque, watch the current drawn by the test motor increase to it's rated value, then read off the torque. Is that right?

[@richardvanderlouis136]

Absolutely love your channel I have several large big Milwaukee Hammer drill and a large12 inch scale saw worm drive any ideas what I could make from them I’m trying to learn more about designing and making useful tools or items for my shop or home as a method of learning more about electro mechanical processes would love your input

[@AugustusTitus]

Great video!

[@quinnfoster4671]

Someone on the esk8 forum was making a dyno stand to test electric skateboard power outputs. I'll link them to this video maybe they could collaborate with you.

[@glennmoreland6457]

Back EMF Back Electro Motive Force Can be an issue with DC drives backfeeding to a generator supplying them... Such as in diesel electric rail traction... A way of overcoming this is through "field diverts".... Several stages of "field weakening" on the DC traction motors.... If you ever visit the UK...then go to the national railway museum in York.... They have a dynamometer car there from the 1930s... A pioneering piece of machinery... There's also one at the national railroad museum, Green Bay, Wisconsin, USA... 🇬🇧🙂

[@mckenziekeith7434]

Are you thinking of the motor he was using as a brake? I believe that is an induction motor, not a DC motor. There is no back EMF. He is just injecting DC into the winding of the induction motor, which causes it to act like a brake.

[@glennmoreland6457]

@@mckenziekeith7434 Rite....

[@atmian]

Very interesting and yes, this is indeed science! Where can I find info on the how the mechanical setup for the test rig works and how to build it?

[@ElderlyIron]

For your display, check out Gale Banks set-up he made for engines. (Banks Power on KZbin.) That'll get your brain working! He's worth watching, anyway. The "Killing a Duramax" series is killer!

[@byronwatkins2565]

Arduino users will need to know 1) specify the electrical signal(s) from the scale, 2) specify the electrical signals from the tachometer, and 3) specify the display to be used. An Arduino timer and a revolution pulse can substitute for a tachometer. Also, torque is vec(r) cross vec(f); if the two are not perpendicular, you need to multiply by sin(angle).

[@ismaeliso]

@Jeremy Fielding , I think it would be awesome if you can come up with a ventilator design out of old appliance motor and make it public..maybe we can all help our local medical facilities cope with their needs

[@otooleger]

Really enjoy your channel. I have learned so much about electric motors. Any chance you might cover VFD to allow three phase motor to run on single phase/

[@55Ramius]

Great video ! Very interesting.

[@chemicalcorrosion]

My shaft USED to produce a lot of power. Not so much nowadays. Ahhhh the good ol days.

[@tienbuivinh5230]

I can help you with the Arduino stuff. Great video btw!