How to Avoid the Biggest RC Brushless Motor Mistake
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- Опубликовано: 6 дек 2020
- Selecting a Brushless motor is not an easy task. That is because there are so many options to choose from and an infinite number of possible solutions. In this video place emphasis on the need to run a few calculations to select a motor for your RC vehicle.
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With the whiteboard, this is like the scale version of Engineering Explained channel.
Exactly what I was thinking...
Facts... That's why I watched it...seems legit just because of similarities 😁
This channel is epic! Been in rc hobby for 25 years and you still bring light on subjects that are grey area for me.
hey Joseph, thanks for the comment!
@@RCexplained😅😅😅😅😅😅 😅😊😅😅😊😮😅😅😊😊😊
man, this was excellent!!! I am Brazilian and learning a lot with your videos, thanks for such a great material in your chanel!!
This is great! Maybe a playslist with noob to pro progression? since ive just started with understanding what it is all about and try figure out where to start! But ive watched a bunch of youre videos (some several times) and thanks again for sharing!
You are number 1. Appreciate all your good work and simplified explanations. Loving your channel 👍
So nice of you
Great topic, and thanks for this one especially. Always spot on info, love these !
Glad you enjoyed! Thanks for the comment Mike!
Very helpful videos. Thanks so much!!
Best video on this subject I’ve ever seen. Thank you vet much
Hey Mark, really appreciate the comment! It means a lot too me.
Thanks for your intelligence brother..
This experience has touched my lack of understanding and now I have something to learn. Thanks again for sharing your information.
Glad to hear that
Good video bubba, these little classes are very helpful, thank you.
Glad you like them!
Thanks for sharing👍
Brilliant! I always wondered how everyone picked the motors they picked. Also I have rock crawlers that run up to 4s but only with good Holmes motors
Thanks for the comment Alohakoa59.
I love your channel I’m new into RC cars and boats. And a GEEK
Thanks for another great video!!
Glad you like them!
Thanks for the very informative video.
Thanks for the comment G3516dude !
Thank you for the informations. great things .....
Hey Isuru, thank you for your comment, question about amp ratings and kind words. Appreciate it!
Is there an online calculator where you put all the specs and tells you the appropriate motor/esc/battery, etc? It would be very helpful for a lot of rc enthusiasts. I bet you're definitely smart enough to make it :)
Thanks for the video. I wish my teacher uses this kind of example in the class.
Thanks for watching!
Thanks for explaoning you are so underrated
Hey Justin, you are too kind. Thanks for the comment!
Thank you very much!! 😊👌👏🙌
You're welcome 😊
Great video!
Thank You xclusve1 guåhan671
Great video. I got lost on the AMPs, power (Wattage?) bit though. I find quite a lot of motors don't include max Wattage in their spec sheets. I'm trying to work out if the new motor/ESC setup I have ordered is going to turn into a crispy wreck or not. Motor is a 3652, 4600Kv, 4 pole. ESC is rated at 60A. I'm planning on running on 2S.
Sounds like it can work. It really depends on your gearing and how much load is on the system. Check for heat and you should be good
Excellent video
Thank you
Very good video but, having been introduced to spektrum I'm very happy as a new to RC enthusist after 15years✔️
Thanks for the comment. Lots has changed in 15 years!
Great expaination 👍🏾
Thanks!
Thank you.
Your Welcome!
Brilliant guidance! when I was last doing fast electric boats, I was using starter motors from large motorcycles and lead acid batteries! Please could you advise as to the rpm range for a deep V hull some 5 feet in length, with a twin motor drive? I saw on one of your previous videos that I should be looking at about half the wattage using a submerged propeller, which was a relief as your calculation guide left me needing an 8Kw motor .....
Yes, it's all dependent on the speed you wish to hit. If you don't care about speed 500w will be enough. RPM range for submerged is 10k-25k. Your build will be on the lower end of this range and possibly even lower depending on what your goals are. 60in is huge.
Did ya get it going? I've got a dumass Deep v ,46inches ,been waiting years to get it going again, this may be the year,chourious what set up you used
Awesome content, subbbbbbbed!
So smart
man i love you
I love your videos and try to make sense of the but my motor esc went on my road car and I’m looking at a 4600kv compared to the 3500 I had just isn’t sure if that’s what I nec
I got the brushless 4370 kk combo I think anyway it’s 37.00 and for 1/10 scale so I put that set up in my exceed short courses truck and used 3s battery . It was pretty awesome until third run I switched transmitter on then the esc and was hesitating so I checked all my connections , battery , made sure nothing was hung up and all wires tight and right ... powered transmitter on and then esc and it tried to take off on low rpm while hesitating to. So I powered transmitter off and it all stopped so I powered esc off to and powered transmitter back on then esc and before I could even do anything the esc started dumping grey smoke And caught fire ...the truck is very light weight and it’s gears ratio : motor 23t and spur 63t . The stock brushed motor had no issue running it except very slow
I have a arrma Limitless I always run a 2200kv max6. In my big vehicles. An ihave alot of them. My Limitless 37t. Leapard 2200kv 6s. I tell u . My crew clock me at. 197. Yes my system gets hot an my esc shut my car down. When it's hot. I'm not sure about my spur I think it's stock. Run a 2200kv max6. 6s. U can't go wrong lost of crazy power. U have to play with the pinion an spur. Good info. Buddy.
Hey I wanna put a 5870 900 kv t.p power motor...that’s the coke can motor in my felony with the mamba xlx2 esc. Can that work and also what gear ratio you think I should run
If you can shoe horn that size motor in there it will be a lot of power for sure. What speeds are you after?
Subscribed. When you say gear ratio, what do you mean? Spur/pinion, or what? Also, do you know where we could find some kind of spreadsheet or something that would help with all these calculations?
Gear Ratio is the overall number of complete rotations the motor rotates for every rotation of the tire on an RC Car. To reduce load on the motor, smaller pinion gear or larger spur gear or both does the trick. Radiocontrolinfo.com has a bunch of calculators and articles to help.
@@RCexplained Thanks!
We need a another rc turbine explanation video!!! GREAT VIDEO!
We will have another turbine video on the channel. Timing will be in 2021.
I’ve bought a7800 kv rocket motor surpass hobby. How do I know what the top rpm and amps would be? I’m aiming for speed runs using a 25t pinion mod 1 can you advise the right pinion gear? I’m gonna use 2s to begin with and move up to 3s no more my aim in 100mph
Any rough recommendations for gearing as a starting position would be awesome.
How do I find out the maximum capacity of a motor or esc no where is it printed on the info that came with the product? How do I find the max rpm of a motor?
For specs, you may have to get this info from the manufacturer.
Hi, I have recently found this channel and like the explanations about motor KV but I am missing something I see everytime I build a RC jet drive powered boat.
I will give an exact example I measured: I tested a boat with the completely same jet pump (same propeller, same load) with two brushless motors, both 3660 size, rated for the same power output, on 4S. The first motor with 1700kv spinned the pump up to 20k RPM and pulled 20 amps. The second 3180kv motor spinned the pump almost to the exact same RPM but consumed 40 amps - outputting the exact same power but being two times less efficient.
The thing I am curious about is this RPM drop under load. With no load, the first motor would spin at 25k RPM, the second would spin at 48k RPM, but both drop to 20k RPM when loaded.
So: How is the RPM drop related to efficiency? Why is the lower KV motor more efficient?
Hello, please email me details of motor, ESC, battery, graphs of data taken to obtain these numbers so that I may look in to it.
I want to make a boat to find fish on ponds as well as mapping the floor, so it doesn't need to be super fast, but will lug around a bit of equipment and probably a wire too... could you suggest a power train combo.... maybe like 5mph is enough stealth and longevity (hours per charge) are more important to me.
Not sure what your boat looks like. Generally for a slow moving boat, you will want to use a low kv outrunner on a relatively low voltage. Power requirements will be low.
Your prop should have a larger diameter with very little pitch.
Hi I need a little info or where to find info on difference between 5mm and 3.175mm shaft ,I understand size and strength but any other ideas maybe heat or something
size thats it
For example 3500kv
Interesting channel, however I don't see any RC helicopter related information. If you could make a video Same as this just in relation to RC helicopters And gear ratio etc. Really would love to see Content in relation to RC helicopters Thanks for the information. Subscribed!
Thanks for the comment Anthony! I don't know much about helicopters. Only had a couple CP small Heli's, that's why you don't see any. At some point I'm sure I will push in to some quad and heli vids.
@@RCexplained can't wait, love information such as this 👍🏾
Thanks you can u exp gears too...and batterys
Thanks for the comment. Yes I can, and I may also have the topic you are looking for on the channel. Check out some of the other videos on the channel. You can filter by key words.
Do you have recommendation for a spreadsheet or Ipone app for KV etc?
what about Kv?
Pushing a 2000kv blmotor. With blx185 thing flies. Idk how good or bad i did there but it drives how I like it. Only gets warm after two 3s batteries run. lol
One way to measure a systems reliability is by temperature. If your components are only warm, less than 60C, that is one positive indication.
So if all my components are correct then I put Uber strong fans on ESC and motor to keep cool on hot days I can gear up a hair right?
Yes, keep your Temps in check.
what is the fastest motor for traxxes sledge?
If my motor has a continuous current of 25 A and burst of 50 A, a max. power of 312 W and i run it on 7.4 V will it try to reach the max power and draw around 42 A or am i just stuck with around 180 W then?
To unlock full potential of the motor, operate it on the voltage that does not exceed maximum rotational speeds. Lower voltages will limit potential power.
I have a arrma infraction v2 6s im wanting to hit speed of 120..what do I need to. Get there?
Check out the Castle 1717 1650KV
Does the gear ratio of the rc car come into play with motor RPM for total RPM. I know that may sound silly but my RC car keeps cutting out and from what I understand it should not be. So I'm wondering if I'm trying to exceed the RPM of the motor due to gear ratio?
A typical rc car power system won't cut out due to excessive rpm.
Thank you I jus was look at motor I bought then this pop up....thx rc bro
No problem 👍Glad I can help.
Why do you leave out drones such as quadcopters from your list of RC vehicles?
I have a castle 3800kv running on 2s 7.4 with stock gear at 13T, 54spur on a 1/10 4x4. On 2s it ran fine no overheating don’t need a fan because it never gets that hot. But it does run somewhat sluggish. I tried a 3s 11.1v and i like the speed and punch but after a few minutes the motor just cutoff. I’m still kind of confused as to why jumping battery power affects motor?
You may be pushing the limits of that system. Check the temps.
Did you put a cooling fan on the 3s set up?
If not, you should'
nerdier than before
Anybody know the watts for a castle 1520 1650?
The biggest cause of people burning out motors and ESC isn't choosing the wrong motor, it's over gearing, the pinon gear been to big and the spur gear been to small.
Great title, it pulled me right in when I read it 😹
Holy smokes great video!
Thanks for the comment BMR. What makes the title more interesting vs other titles?
@@RCexplained I’m not sure, but this one has some special sauce on it so I wanted to let you know.
I normally don’t get pulled in by titles but this one sucked me down the drain.
Nice, thanks for the feedback!
For me it was the thumbnail. It questions should you put a certain motor into a certain car.
Hmm interesting
Thank you for the explanation ! i have a situation: 2s LiPo on 3660 2600kv motor/ 60a esc on 29t pinion. fitted in a 5lb buggy. will i be able to hit 40mph ? inviting the master himself as well as anyone with expertise to advise me ! thanks
I'm still trying to figure out how to do this but basically you need to know your final drive gear ratio
Once you know that then you take your volts x cells x kv for your motor rpm then take rpm ÷ final drive for axle rpm. And as for the speed you would also need to figure out how to convert wheel speed to mph or kmph and that usually depends on wheel size but thats all I know best of luck
@@Bombzaway8222 thanks alot for your effort man! i am going to use this formula after getting the necessary data
I have a problem. In this case mentioned that motor can handle 98amp s max. is this real rated amp or some kind of a notaion of amp. On the other hand i saw a esc can handle 60 A . Is this real rating? Can esc with such thin wires handle 60A amps ?
Hi Isuru, this comes up quite often and will be a video I make in the distant future. The wires are not as thin as you may think. The reason is because of the length of the wire. In a typical house in North America, we use 12 or 14 gauge wire for about 15A of current. The difference here is the wire is running well over 60ft in length. Our ESC's and motor's using the same gauge of wire are usually less than 2ft in length. A huge difference. This is why they can be rated for a much higher current then you may be use to.
In RC, all the current ratings you see are indeed in amps. What you need to watch out for is continuous ratings vs peak ratings. This is very important.
Thank you for your kind explanation. I think i got the point. Your videos and explanations are really valuable. In our countries it is very difficult to find real technology. We got so many big things from your video. Thanks you again. Wish you for the videos at the bottom of my heart. keet it up.
Thanks Isuru!
Please make one of the videos for 4x4 monster truck... like my new arrma big rock that is like to upgade one day😎🍻👍🤣
What are you hoping to see in the video?
i have an lrp x11 3t motor with these specs: RPM 82.080 kV 11400 Power 745 W and i will run it on 3s no more
What esc should i use?its sensored
Thank you
Hi gyubrush, can that motor handle 3s? Is 82,080RPM the maximum? That is already very high.
@@RCexplained thanks for the reply
The 82080 is the max rpm and because of the high kv i was thinking also the nimh batteries or the 3s at maximum so not to max out the motor
When I do the kv divided by nominal Lipo the amps go down, is that right?!! 2310w divided by 7.4 equals 317 but 2310w divided by 14.8 equals 156
2310w is watts or power. I don't see where you used kv. Using more voltage will allow the current to decrease as you have proven.
@@RCexplained 2310 watts
Is it right that amps go down as volts or cells go up?4s then 6s then 8s
New to your channel'
I have this problem;
Subject: 28" inch deep v speed boat yacht
Set up: reedy 540 sl4 brushless 3300 kv 4 pole motor, hobbywing 60 amp marine speed control, 7.4v 50c 5000mah lipo.
Issue: once I get the trigger to full power, it gives full speed for a couple of seconds, then it goes into lower cruise speed, still with the finger on full trigger. Cannot figure out what's wrong'
Everything it's brand new out of the package'
The set up has not had even a chance to get hot'
Any suggestions? I'm at a loss of options and money here'
Have you measured how much current (amps) the motor draws at full power. The electronic speed controller reduces the output power if the motor draws too much current.
My suggestions are to measure how much current ist flowing and use an ESC with higher amperage.
I had a similar problem, in my case the cut-off voltage in the ESC was set to high and the motor didn't run at full speed. At half throttle the ESC switches off the motor. My solution was to buy a hobbywing program card and set a lower cut-off voltage.
My setup
Lipo: HRB Power 12S 6000 mAh 50C (4x3S lipo),
ESC: Hobbywing Flyfun v5 130A
Brushless motor: Eagle Power EA98 KV120
propeller: 3080 inch carbon fiber propeller.
I use that primarily for other things, so building wind machines.
@@pyrodancer5126 tnx very much '
I will try your suggestion and I'll get back to you with my findings'
Probably drawing too much current, either run a smaller prop or get an esc to run higher current.
You can also try running a much smaller prop or less agreesive pitch but using 3S instead of a 2S to achive a similar speed, that way your using higher voltage to achive the same power instead of current draw also note that method only works when you're trying to just get the same amount of power from higher voltage either by smaller prop, gearing down or using a lower kV motor, if your going up in voltage to achive higher speeds and power your over current problem will not go away and may even get worse.
Can I use a brushless sensored motor on a sensorless system without messing up the motor
You can use a brushless sensored motor on a sensorless ESC. The system will act as sensorless.
1) overvoltage 2) gear pinion engange is not correct 3) overgearing 4) lack of cooling(i am reffering to vehicles of course)
What about multirotors?
I've been fixing up my oldest RC car that I got back in highschool. This thing overheated and broke CONSTANTLY to the point that it got so frustrating that I completely quit the hobby until a few months ago. Now with some hindsight and maturity, I see that it was probably a poor idea to "upgrade" the motor by switching to one of the same size but moving from 3300kv to 5700kv, while at the same time moving from the stock 23t pinion to a 29t, while also at the same time moving from 2s to 3s. Now I see that I was essentially setting it up to be a speed run car, because yeah it would completely overheat in about 3 minutes of running but damn could it go fast in a straight line (before inevitably slamming into a curb)
At this point im still using the 5700kv motor, but switched the pinion down to a 17t and and now its a 2s car. It works pretty fantastic now.
I really wish there was a youtuber like you back in the day, would have saved me so much trouble haha
you can run the 6s application on the buggy cause the motor will NOT reach 60.000rpm under load ~ just lower your gearing
That is true but there are limitations to how far you can lower the gearing. Especially if your RC model does not have spur gear options to support such RPM. This is why I have placed that RPM band in the range of "experienced" users. An RC car builder with your level of understanding would be able to make it work.
hi! was just wondering about the formula. why does it matter how many cells the battery has? its voltage is still 3.7V regardless if you add a cell to the battery. In any case you just add more Amps. for example 1 cell 1000mah 2 cells 2000mah. can u plz explain:)
cells in series
@@RCexplained ok, but the total cells combined is still 3.7v😅 i dont get it🤪
@@ostpong 2 cells in series makes 7.4v.
@@RCexplained yea i meant 7.4 not 3.7 but the cells could be lets say 10 in a battery. each cell has to be 0,74V to make 7.4V in total and thats fine. but why is the cells in the formula?xD thats my question here.
I'm not following you. Lipo cells are 3.7V nominal. If you have 10 cells in series that is 37V. 4 cells in series is 14.8V.
Well I’m defending the 6s battery. You could change how it’s wired and then say “ we can run the 6s for this application “.
My 6s battery would have to be cut in order to rewire it to another configuration. It is just one pack.
Perhaps you are talking about having 2 3s packs?
@@RCexplained yeah 2 3s ran parallel.. or 4 in series and 2 parallel
Yes 11.1v would be very different.
what about the drones?
Same idea applies to Drones!
I always stuck with 2200kv motor in my 1/8 scale vehicles
2200kv works well for most 1/8 scale buggies for 6s! That is also what I dropped in to a 1/8 scale buggy.
@@Shadows-RC a 4074 2200kv motor is more than capable of running a Kraton. just don’t over gear it. stay with a 12-14t pinion with standard tires
Uhh and I just made a boat and wanted to transfer all from rc car. I knew motor is too powerfull for boat but I thought it will be fine with larger prop and not going full speed. Guess not
It's likely that a car motor is not powerful enough because the Kv is much too high. If so, the motor would burn out from over heating.
I think I missed the point that the motor is getting this energy regardless. It’s about the motor .
Seeing as you are so helpful I have a practical question.
I have a 3s 1/8th buggy with a 3200kv 3660 motor. I also have a 3674-2650kv motor and big 6s lipos. I know the motor can handle this kind of RPM since it was previously used on this voltage with an airplane propeller at 200+amps. The current car has an 18t pinion. I can fit a 13T (maybe 11T with modification). Maths says I should be close so ok - 3s x 3200 x 18 = 172800 vs 6s x 2650 x 15 = 206700 - the differential between the 2 in rpm at the drive is around 19-20%, the differential in motor size/surface area is >23%. How about with a 75% throttle limit?
I understand the electronics but I don't understand drive losses and relative loads in rc cars.
Merry xmas, I hope you read this after that's relevant and you have a great day with your family.
Hey Fraser, I'm not following your math. What is the 172800 and the 206700? What is 18 and 15 in the formula that you are using to get these large numbers?
Merry Christmas to you too.
@@RCexplained Apologies, I was doing cells x kv x pinion size for a comparative value at the spur, all other variables are the same. 18T vs 13T is the available pinion for each, I can go down to a 13T and a 18T is known working for the existing setup. I'm trying to close the relative difference in motor RPM with the gear ratio on the pinions. (3s x 3200 vs 6s x 2650 then x by the pinion teeth).
On a plane I'd just prop down and use ecalc to guestimate where to start, I don't know how much changing the gearing on a car deloads the motor.
I watched your other high KV motor video, I understand trying to drive gearing too fast can be amp hungry. There's not much data around quantifying that, car guys don't seem to be that into electronics and data logging.
It's a lot different for quantifying car data vs plane. A plane always experiences the same load in an RPM and airspeed range. Cars have varying loads depending on a lot more factors.
You definitely can reduce and offset load by changing gear ratio.
@@RCexplained That has given me a bit more confidence. Useful to know I haven't been shot down straight away. ;)
I think the first step is to get a flight controller in it and get some data logging going.
Thanks again for responding. It was most helpful to talk it out.
If your car ESC does not have data logging, you can use a standalone unit.
How does one contact you by email??
should be on info page.
Don’t try saying this ain’t rocket science.
Do you have a Facebook page?
Yes, link s on the about page.
Honestly I just bash but like it fast
That is exactly me as well. If we have selected the components correctly then it's fine.
I want to move 100 kg
How many kV motor required
Any kv could. Depends on the rest of your setup
@@RCexplained you mean gear setup
And the battery, esc, size of motor selected.
I don't think you mentioned motor to weight of vehicle?...which I believe is a huge part of it
Also great job 👏
Yes this is definitely part of the equation however I see more kv problems then anything.
Yes true
My wife said your video is non sense: The biggest is better, all other parameters are driver skill or loosers complaining with maths why they have a little one.
If you do not have enough room on your car you can even use a motor bigger than your car using a secret pro tip: Put the motor (or two motors) in a big trailer.
I like to think bigger is better, however a kraton exb with a 1/5 800kv motor although will work will sure make the truck go like stink but it will handle like crap and be so heavy that a remotely heavy crash will likely just break the truck.
You do need a good middle ground and not an extreme at either end.
@@markmmm1737 Of course you have to adapt the car to the big motor. If someone is complaining of a big motor: This mean he did not found solutions for his weak roller or weak tires or weak transmission and it does not mean the big motor is the trouble.
For my motor I had to find glue to stick my tires on the road because tires where spinning even at high speed. The big motor was not the trouble, the trouble was the tires. Now I use motorcycle chain wax on my foam tires: It really make noise when I unglue it from the road (seriously). :-)
Your math is based on batteries ran in series. Run series and parallel together and your rpm will drop because the voltage will decrease and mah will increase right? I’m stoned sry man.
If you run lower voltage, yes RPM will drop.
you gave some false facts, if motor has 2000w at 98 amps it means there is 20.4 v, P=UxI, so U=P/I, and here you started to fail, now you should found resistance of motor and it is if I=U/R, then is R=U/I, what gives R=0,208 ohms, so with less voltage you can not get more ampers than 98, so your calculation for 14.8 v and 11. 1 v are totally wrong, at 14.8 v I=71A, and at 11.1 v I=53.4 A, did you have in elementary school basics of electricity, i had
Then you should know that it’s not written P=UxI (like you did because it’s confusing and wrong) it’s simply P=UI. Even worse you are wrong. You are using the resistance of something that has a voltage of 20.4 on a calculation on a problem with 14.8 volts. Of course when you drop in voltage current increases. Elementary boi.
@@user-ds6ur2og5p you are wrong , how you can get more current with less voltage, with same resistance,(voltage pushes current), this motor has peak power at 98A and voltage at 5S, if you want same power with less voltage, motor must be designed with thicker and shorter wires to get less resistance, then tesla would not have 800v in car because your logic would say that 400 or 600v is enough, go back to school
All fine and dandy if the motor manufacture has the max RPM noted.