RC BASICS: What is KV?

แชร์
ฝัง
  • เผยแพร่เมื่อ 19 ม.ค. 2013
  • When using electric motors to power RC model aircraft you'll often hear the term KV - so what is it?
    In this video, I explain what KV is and how it can be used to calculate the RPMs of a motor when powered from a battery of a known voltage. I also demonstrate how to measure the KV of a motor when it is unknown -- although you can buy a KV meter which will do the job much more simply if you want.
    I'm sorry that this video is a bit long -- I may re-edit it later and shorten it up a bit.
  • วิทยาศาสตร์และเทคโนโลยี

ความคิดเห็น • 642

  • @scottmarshall6766
    @scottmarshall6766 10 ปีที่แล้ว +73

    I'm an electrical engineer who has worked with all sorts of industrial variable frequency drives, Pwm limited stepper motor controllers, 90 and 180vdc DC speed controls etc. for nearly 40 years.
    I've been baffled by all the techno-babble garbage supposed experts have been pouring onto helpless RC builders who don't know what to think. The RC forums are full of "experts" expounding on meaningless formulas which are either mis-applied or totally ficticious. It's infuriating, but I, being a gentleman, have resisted the temptation to point this out to any of them (so far).
    THANK YOU FOR CUTTING THROUGH THE BS!!
    You are the 1st person I've seen who really knows what they are talking about. Great demo and explanation! This video should be required reading for anyone buying a motor. Well done sir.
    Best wishes for your continued sucess.
    Scott Marshall
    Elbridge NY USA

  • @jonbbaca5580
    @jonbbaca5580 6 ปีที่แล้ว +32

    There is no way you're getting paid for how much useful knowledge you're providing to the modern RC community. I guarantee your videos and explanations have helped SO Many modern component manufacturers to figure out how to design and build their products thatve changed the whole game in RC flight. You're like the Wikipedia for RC model designers and production companies. You're like the printed Encyclopedia for the newer generation to reference and design their next generation RC products. Without ppl like you, our generation of engineers would be totally clueless. Thanks for your service of distilling a generation of electronics and RC knowledge for us to use!

  • @MidwestRob
    @MidwestRob 11 ปีที่แล้ว +1

    I learn something new every time I watch one of your videos. You explain everything in a way that is very easy to understand. Thank you for your extraordinary contribution to this hobby.

  • @jj01a
    @jj01a 11 ปีที่แล้ว +1

    I love your channel, thank you for the time you invest in sharing. You do a wonderful job of explaining complex topics, it's a gift.

  • @gregmcdonald5986
    @gregmcdonald5986 7 ปีที่แล้ว +8

    I just wanted to take a moment to say Thank You for the educational videos. I'm just getting back into RC after last flying glow plug engines some 30 years ago. To say things have changed would be an understatement, to say the least. There is no local flying club so the only education I get is from a few select forums and TH-cam. I've made a few videos myself and can definitely appreciate the time it takes. Thanks......

  • @seattleman6297
    @seattleman6297 8 ปีที่แล้ว +3

    very interesting. Thank you for this video, subscribed and liked this is the only clear informational RC source on the internet.

  • @samacumen
    @samacumen 11 ปีที่แล้ว +1

    Thank you. Simple, straightforward and amazing to a beginner. Keep it this way, thank you again :)

  • @rtonce
    @rtonce 5 ปีที่แล้ว

    The car gearing to KV rating on a motor finally made that clear for me. Thank you.

  • @DobyxRC
    @DobyxRC 11 ปีที่แล้ว +2

    Thanks for keeping it simple, I'm sure there's more to this subject and tons of variables.

  • @SergioNayar
    @SergioNayar 6 ปีที่แล้ว +2

    You sir, are a great teacher!!! Very gifted teacher!!! Thanks!

  • @pufferfish0567
    @pufferfish0567 11 ปีที่แล้ว +1

    Thanks for putting this series together. I have just recently started converting from glow and this is going to be a big help.

  • @catamaranman333
    @catamaranman333 11 ปีที่แล้ว

    Thanks again Bruce for offering up such great essential information for so long!

  • @richardt1
    @richardt1 7 ปีที่แล้ว

    What a helpful video! I hope you still read these older comments. I'm in the U.S. when I was a kid, in th 50's, we used to have a tv program called Mr. Wizard. He would explain concepts in a similar manner. He would place it in real world applications, explain the instruments and tools, and provide great visual examples. Unlike some, when it comes to electronics I am dumb as dog food. I know how to google formulas but it's the understanding and application to RC that's the hard part. Your series is right on target for a newbie who wants to understand these things as they are used in his hobby. Please keep up the great work. You bring value. Richard t.

  • @iandavis6742
    @iandavis6742 8 ปีที่แล้ว

    Clear and easy to follow .You and 360 painless are the best videos on u tube .Thank you

  • @SC-lm1dt
    @SC-lm1dt 3 ปีที่แล้ว

    After some years involved in small RCs, I now understand what KV means. Thanks Bruce!

  • @jhiggason1
    @jhiggason1 11 ปีที่แล้ว

    These are incredible helpful! Please keep going! I'm going to share these around to make sure that people just starting like me get your awesome help.

  • @StonyRC
    @StonyRC 10 ปีที่แล้ว +7

    Excellent video - many thanks for helping me to understand. We need more people like you to help newbies like myself.

    • @xnoreq
      @xnoreq 5 ปีที่แล้ว

      Kv is the reciprocal of the back-emf constant.
      A 500 Kv motor will generate a 1 V back-emf when the motor is rotating at 500 RPM. At 3700 RPM that motor will generate 7.4 V.
      Applying it the other way around ("7.4V will make the motor rotate at 3700 RPM") is only an approximation and technically wrong.
      This video is actually full of misinformation because RCModelReviews relies on the latter understanding of Kv which is wrong.
      The motor RPM is NOT calculated by V*Kv. The actual RPM = (V - R*Io) * Kv = (Voltage - Motor Resistance * No Load Current) * Kv.
      So given the above motor with R=0.5, Io=1, we get 3450 RPM at 7.4V.
      Also, Kv tells you nothing about how powerful or efficient the motor is. That's another point where RCModelReviews is wrong. High Kv does not mean the motor has low power.
      You can get high Kv motors with higher power than low Kv motors....

  • @chiro30
    @chiro30 11 ปีที่แล้ว

    Ooooh.....nicely explained and continues to be a shinny forum of info for us new or somewhat new to the hobby. Much thanks.

  • @RaduB.
    @RaduB. 6 ปีที่แล้ว

    Hello again!
    For some reason (...) I decided to watch all your videos chronologically.
    So your trade is electronics 🙂. That explains a lot...
    Thanks for posting!
    And on we go... we are still way back in the past...

  • @richabout
    @richabout 10 ปีที่แล้ว +1

    Thanks for the Vid! It has helped me to understand the basics. Top Job!

  • @jchtr3ac
    @jchtr3ac 11 ปีที่แล้ว

    Thanks Bruce. That cleared up a lot of my questions. The analogy you did with the car gears brought it into focus for me very well. I get it!
    Cheers.

  • @MrGpse
    @MrGpse 11 ปีที่แล้ว

    Thanks Bruce, this video has been more informative than the past dozen hobby shops in my area. Looking forward to pt. 3 of the XG8 review.

  • @NicholasMorganUSA
    @NicholasMorganUSA 11 ปีที่แล้ว

    I know most of this stuff, but this series is still really enjoyable to watch. Looking forward to the next parts in the series. . .

  • @MarkFletcher16-07-76
    @MarkFletcher16-07-76 10 ปีที่แล้ว +5

    Awesome, thanks very much for clearing this up!

  • @agentbertram4769
    @agentbertram4769 6 ปีที่แล้ว

    Thanks Bruce. When I was a commissioning engineer on Shell Stanlow oil refinery, a 6.6kV motor was the size of a Ford Transit van. You'd never get one to fly or if you did, you'd need one big battery and an inverter from the planet Krypton. So it's revs/minute/Volt (ish). Brilliant!

  • @PugetSoundFlyer
    @PugetSoundFlyer 11 ปีที่แล้ว

    Many thanks for this well done video.
    You've guided me from ignorance to knowledge !

  • @pyrexia2
    @pyrexia2 11 ปีที่แล้ว

    Great vid as ever Bruce,looking forward to the follow up vid ,you explain it so well.All the best Jez

  • @pyramid360
    @pyramid360 7 ปีที่แล้ว

    thank you so much for these videos. you really helped us in preparing for SAE competition

  • @wnleon
    @wnleon 9 ปีที่แล้ว

    Great introduction to KV. Sure it will set off the EE guys, but this is a very practical explanation that is clear and easy to follow. Good job.

  • @MrHanzeeman
    @MrHanzeeman 11 ปีที่แล้ว

    Thanks Bruce! I love this series, keep them coming.

  • @ADVscooter
    @ADVscooter 11 ปีที่แล้ว

    I really like this RC basics series!

  • @nakul3424
    @nakul3424 8 ปีที่แล้ว +1

    This was so so informative. To the point. thank you.

  • @GreyhatInfiltrator
    @GreyhatInfiltrator 10 ปีที่แล้ว

    I've learned quite a lot from you and the videos always very enjoyable to watch. Hope you continue making more great videos. Thank you.

  • @MyCatInABox
    @MyCatInABox 8 ปีที่แล้ว

    What a bunch of great, entertaining and informative videos you have. I subb`ed as soon as I was done watching the first vid (explaining KV ratings).

  • @peterlution
    @peterlution 11 ปีที่แล้ว +3

    Thanks, Bruce. In order to stabilize the tachometer reading, you should avoid florescent lighting. I use an LED flashlight to override the noise from ambient lights.

  • @henri-julienchartrand3387
    @henri-julienchartrand3387 2 ปีที่แล้ว

    I agree with Jon B. What a great teacher you are. Respectfully.

  • @PilotDamian
    @PilotDamian 8 ปีที่แล้ว +1

    Great videos!
    Btw, can you tell me where did you get that little speed control that connects to the ESC? I need one just like it! Thanks !

  • @stukingman6438
    @stukingman6438 11 ปีที่แล้ว

    BRAVO! Once again, informative and complete in (The King's) English. I always enjoy your videos. Keep up the fine work.

  • @alanjames2333
    @alanjames2333 9 ปีที่แล้ว

    Hi Bruce, I'm new to this stuff. Thanks for these entertaining & informative videos, I've watched several.
    Is the speed controller you use in this video an off the shelf item that I can buy? Thanks

  • @pvantuel
    @pvantuel 11 ปีที่แล้ว

    Thanks Bruce. I've been flying for donkey years, but never understood the motor sizes... This video is very helpful.
    I'm looking forward to your next video about props in relation to motors. Cheers.

  • @catfishmudflap
    @catfishmudflap 10 ปีที่แล้ว

    Great video, explanation and demonstration. Thank you.

  • @michaelgrossman5528
    @michaelgrossman5528 6 ปีที่แล้ว

    Thanks for sharing your wealth of knoledge with us and taking the time to simply explain so everyone understands i love your vidios

  • @PC9JEFF
    @PC9JEFF 11 ปีที่แล้ว +1

    Lol, I wish this vid was available 5 years ago :)
    Thanks for sharing Bruce!
    J

  • @Cyberdactyl
    @Cyberdactyl 11 ปีที่แล้ว

    Looking forward to the next video. Motor nomenclature has always had me befuddled.
    Thanks for the very informative videos Bruce.

  • @MattNicassio
    @MattNicassio 9 ปีที่แล้ว

    I went through your WHOLE video history but never found anything about Prop size or 2 vs 3 blade or how to pick a prop for a motor, or a motor for a specific mm size quad. Your videos are the best on YT for RC, but have you done a follow up for your RC Basics series on motors / KV / ESC's - you mentioned next would be about props and how to combine it all? I'm interested for QuadCopters mostly but fixed wing is something that will interest me in the future certainly.

  • @a10augie
    @a10augie 10 ปีที่แล้ว

    Thank You ,great job very informative and easy to understand.

  • @rpgeezus
    @rpgeezus 11 ปีที่แล้ว

    Awesome video! Am really enjoying your newest stuff. Looking forward to more. Keep em coming! :)

  • @cynr100
    @cynr100 11 ปีที่แล้ว +1

    Great vid , thanks Bruce.
    When you do your power vid will this also include "timing", I comprehend what this does but have difficulty in explaining.
    The question arose on the RCMR forum but my explanation was anything but helpful.

  • @brianTwwjd
    @brianTwwjd 10 ปีที่แล้ว

    Good stuff. Thanks for taking the time.

  • @paulr3556
    @paulr3556 8 ปีที่แล้ว

    Awesome videos and explanations. Been watching your vids for a while now, just only signed up with TH-cam. And fairly new to the quad scene, been an electric off road car hobbyist for years. Hopefully you have your "wings" back by now officially.

  • @samadvanes8711
    @samadvanes8711 9 ปีที่แล้ว +6

    I love it when you start looking for things... :D

  • @RajendraVermaa
    @RajendraVermaa 4 ปีที่แล้ว

    Thanks for the information. Very well explained.

  • @DanCreecker
    @DanCreecker 11 ปีที่แล้ว

    Hello, thanks for explanation. Where can in found the same regulator connected to your esc ?
    Dan

  • @patriotir
    @patriotir 7 ปีที่แล้ว +1

    awesome video! I wish u could explain about thrust as well n how to choose the right motor for our model n how to match it with ESC n battery

  • @CrucialStuff
    @CrucialStuff 8 ปีที่แล้ว +1

    Just for you'r info. Your video helped me to learn even throught i'm not interested in RC and more on building a electrical skateboard! Greetings from Spain!

  • @sicroly
    @sicroly 11 ปีที่แล้ว

    hey where did you get that variable controller from? please advise. thanks. nice job

  • @drumrboynoid
    @drumrboynoid 11 ปีที่แล้ว

    Hi Bruce! Thanks for the video. Question; where can I get a good watt meter? A good one that's cheap. Do you think Hobby King would be sufficient or would you go name brand? I appreciate your time. Thanks

  • @roberta.6295
    @roberta.6295 8 ปีที่แล้ว

    Thank you for a great presentation. Its very helpful to actually understand this as I am new to flying Quad copters and currently using brushed motors in low cost quads. Ive been considering converting a Syma X8C to brushless motors and now I better understand the theory of operation. For the X8C what KV motor rating would you recommend? As you have the 40 yrs in this and can make the best estimation off the top of your head. My 40 yrs experience is in Mercedes Benz and BMW cars. Thanks again!

  • @TilmanBaumann
    @TilmanBaumann 11 ปีที่แล้ว

    Great series. I hope in the end you can make a guide on how to select a powertrain for any model.
    Like, how does it fit together, how can I apply all those basics to buy the right motor/prop/ESC/battery the first time round for a new model.
    I tend to go with, what did others use for similar planes or what does the ARF version use. But I never feel like I know really why this combination is right. I just improvise.

  • @JeremyAverett
    @JeremyAverett 9 ปีที่แล้ว

    You're a genius. Another excellent video! Thanks.

  • @raymondboots6089
    @raymondboots6089 6 ปีที่แล้ว

    That clarified everything. Thank you very much!

  • @corum10
    @corum10 5 ปีที่แล้ว

    Hey!! Nice video, thanks. Can you tell me where you got the manual pulse generator for the ESC? I really like it compared to mine.

  • @mohamedsheikh2502
    @mohamedsheikh2502 3 ปีที่แล้ว

    Thanks a million for telling us what a KV stand for ..Regards from California

  • @ForkinCrazy
    @ForkinCrazy 5 ปีที่แล้ว

    Thank you!!! Best explanation I have seen!!!!

  • @ucrash2
    @ucrash2 10 ปีที่แล้ว

    Well done! Makes it easier to understand for sure!
    How about a vid on ESC TIMING ISSUES AND MULTICOPTER ESC TIMING

  • @urimel100
    @urimel100 2 ปีที่แล้ว

    Great video - so clear - thank a lot. BTW, did you make a video about choosing the right prop for e-motor?

  • @moonchildoforcamoon6272
    @moonchildoforcamoon6272 8 ปีที่แล้ว +1

    I noticed you say "Rule of thumb" a fair bit. For those who do not realize this term was coined in the before time when people would brew beer and without thermometers would use there sensitive thumb to test if the temperature was right to add the yeast for the fermentation process hence rule of thumb. Great channel, I always thought of Kv as Kilo volts also before watching this :)

    • @vertigo6982
      @vertigo6982 5 ปีที่แล้ว

      In the movie Boondock Saints a huge man-hating feminist lesbian pointed out that saying meant back in the medieval times or earlier a man was legally able to beat his wife with a stick no bigger than his thumb.
      One of the Irish twin brothers who are the lead characters who was training the huge woman with on-the-job training in some meat warehouse then jokingly replies( knowing the woman hates men by the "Never touched by man" tattoo under her chin) , "Rule of thumb? Well what's that gonna do? Perhaps it shouldve been rule of wrist?". Which of course led to a fight where the boys convinced the woman to keep her comments to herself with a right hook to her chin.
      Damn good movie.

  • @MrTaz0079
    @MrTaz0079 11 ปีที่แล้ว

    Thanks Bruce you answered a few questions,what was the device you used to replace the receiver ?? and where did u get it from??

  • @Tube2Jet
    @Tube2Jet 10 ปีที่แล้ว

    Thank you I'm quite new to this and your video really helped

  • @Lilledritt1976
    @Lilledritt1976 11 ปีที่แล้ว

    Hi Bruce!!! Love the videoes... I do have a question you didn't mention in this video... What about the number of poles?? what would be the most efficient for multirotor platforms...

  • @tomnwoo
    @tomnwoo 10 ปีที่แล้ว +1

    Bruce, great video as always.
    Can you please do a video explaining the effect of pole count and star vs delta windings on output RPM and torque

  • @srwilliams1963
    @srwilliams1963 11 ปีที่แล้ว

    Great video, keep up the good work. Am looking forward to the power video

  • @YazinS
    @YazinS 7 ปีที่แล้ว

    Great explanation -- what is that device that you used to control motor speed?

  • @danieljckson
    @danieljckson 10 ปีที่แล้ว +1

    great vid, awesome, I had no idea what kv meant. Thank you!

  • @MrBillson1234
    @MrBillson1234 10 ปีที่แล้ว

    thanks,, can you put the next vid in the series as a responce vid so i dont have to trawl through your chanel to find the linking vid ? just a thought , have seen others do that how do these bl moters turn , you said they only light up two magnets at once ? or is tht to basic a question ? cheers

  • @eagsalazar
    @eagsalazar ปีที่แล้ว

    @RCModelReviews, did you ever put up the power video you said was coming next in this video?? I looked in your videos list and didn't see it. I'd *really* love to watch it.

  • @accord727
    @accord727 10 ปีที่แล้ว

    Great video explained very well. Tell me though, what is the name of the device you used to adjust the speed of the motor and where did you find it? That would make balancing very easy as well

  • @cactusjackthedesertrat5601
    @cactusjackthedesertrat5601 2 ปีที่แล้ว

    Great video thank you for taking the time to make it

  • @GuyOnTwoWheels
    @GuyOnTwoWheels 9 ปีที่แล้ว +1

    Finally this is explained, thank you! No to go find the prop video!

  • @joegarcia4233
    @joegarcia4233 10 ปีที่แล้ว

    Hello. I was wondering, where did you get you speed control switch from?

  • @LWJCarroll
    @LWJCarroll 11 ปีที่แล้ว

    Bruce that's an excellent and informative video!!! I look forward to the one you mentioned for selecting a motor for a model. BTW are plans available for the 3D yellow model??...Rgds.....Laurie

  • @Rcd872
    @Rcd872 4 ปีที่แล้ว

    I’m an rc car enthusiast. 3 years ago I made the switch to battery and these small dc motors. I’m trying to learn the theory, terminology and practical from using chemicals to generate electricity (to more clearly understand the battery) to the use of electromagnetically spinning a rotor to power my rc trucks. Please continue your series and do you have a book you could recommend to a beginner to teach the basics. Thanks

  • @ironcobra98
    @ironcobra98 9 ปีที่แล้ว

    Thank s for a great and informative video, do you have any video explaining the relationship between brushless motors, selecting appropriate ESC's and batteries? This is something I am trying to understand in terms of matching the electronics on my planes.

  • @amtpdb1
    @amtpdb1 11 ปีที่แล้ว

    Bruce:
    Thanks for explaining this and I am waiting for the rest of the videos. I hope you can explain the number of wraps on each pole and how the number of poles effects the power and or rpm.
    Thanks again.
    Don

  • @alexmecanique
    @alexmecanique 11 ปีที่แล้ว

    really instructive, NOW I UNDERSTAND KV !! thanks !

  • @0917bobb
    @0917bobb 11 ปีที่แล้ว +1

    Excellent job Bruce.

  • @dekutree64
    @dekutree64 8 ปีที่แล้ว

    Did you ever do the video on motor/prop selection? I can't find it.

  • @blitzfultime
    @blitzfultime 9 ปีที่แล้ว

    Good detailed videos sir, subbed.

  • @michaelland6693
    @michaelland6693 5 ปีที่แล้ว

    Great Work! Can you possibly post a link of the potentiometer you used?

  • @cjones4433
    @cjones4433 4 ปีที่แล้ว

    This is what I was looking for. I know this is an old post, but was your tachometer set up for two bladed props? Wouldn't that mean that your calculations should be half? This is not a criticism, but me making sure I understand KV. This is a good video, and I learned alot out of it.

  • @daxdadog
    @daxdadog 11 ปีที่แล้ว

    Bruce, You mention the trial and error approach to motor/prop selection. Have you tried using Webocalc?

  • @mohamedalzarouni6738
    @mohamedalzarouni6738 9 ปีที่แล้ว

    hi thank you for this clip. i want to know what type of speed control for switch on and off in this clip

  • @MathieuMarchant
    @MathieuMarchant 10 ปีที่แล้ว

    Nice video and put in an understandable way. I didn't manage to find the video you were talking about for matching the props with the engines. Is it possible to provide me a link?

  • @yetanotherproject-ce2nm
    @yetanotherproject-ce2nm ปีที่แล้ว

    Great shop teacher! I feel like I'm back in technical school.

  • @thecrazykartbyAJ
    @thecrazykartbyAJ 6 ปีที่แล้ว

    Excellent video, thank you very much.

  • @randyneighbour
    @randyneighbour 11 ปีที่แล้ว

    great and very easy to undrstand info bruce thanks for shreing

  • @sergiobonvini7190
    @sergiobonvini7190 5 ปีที่แล้ว

    I just wanted to thank you also for the educational videos. The electric planes are all new to me as I used to fly RC motor aeroplanes. I also have a question, would you be able please to advise me where do I buy a speed controller similar to yours shown on the video, very tiny but so efficient!, many thanks......... Sergio

  • @DusanHlavaty
    @DusanHlavaty 11 ปีที่แล้ว

    I'm interested in that little controller with a knob, too. What exactly it is ? Where can I get one like that ?

  • @nlimchua
    @nlimchua 10 ปีที่แล้ว

    have you tried using the tach on an 'in-runner' motor? I'm curious how you're going to mark the tiny diameter of the in-runner shaft.

  • @etopsflight
    @etopsflight 9 ปีที่แล้ว

    any brand/part number for the speed controller used in the video to change the speed of the motor?