Motor specs

[Jourduson 35]

Hello every one, I'm new to this club, and have just begun building/driving rc buggies last year. I'm into Lego Tecnic too and have come to realise that the Lego community has a much better technical documentation of the Lego compatible motors than many of the manufacturers. All the data is standardised for comparability at one glance, especially amperes, rpm and torque in Nm at 6V and 7,2V.

I miss this consistency. Also some manufacturers give practically no information on their motors almost as if it were a big secret.

Rule of thumb: ESC Ampere continuous rating should be 30% higher than the motor Ampere rating without load. No manufacturer gives that motor rating.

If all this data were standardised as like in the steel industry, which I worked in for several decades, life would be a lot easier when looking for specific combinations.

How do you as a community go about choosing ESC/motor combinations?

Cheers!

 

 

[Twinfan 2013]

Gearing is a big thing.  You need a motor that will work with the often limited range of gearing in a Tamiya kit.

Then get an ESC to match the motor you want to run  

[El Gecko 1518]

I agree, it is completely frustrating! Especially when looking for a motor with "more torque" than your current motor, it's not an easy spec to find. And yes, amp and torque ratings on motors would help a lot!

But in the meantime the best we can do is what they give us. Most ESCs have a list of specs for certain battery and motor combinations. Such as: don't go below a 15-turn 540-size motor with a 7.2V NiMH battery, or don't go below a 12t 550 motor with a 7.4V (2S) Lipo battery. Some are limited by battery size as well, usually topping out at either 2S (7.4V) or 3S (11.1V).

If you know the turn count of the motor you'd like to use in a particular car, you just need to find an ESC with specs that work with the motor and battery you have in mind (most here use the Hobbywing 1060 or similar clones). Also you'd want to match the type of battery connector on the ESC to whatever battery you'd like to use.

The specs don't cover all cases though, since different motors from different brands may have different amp ratings, even with the same turn counts. So if you're close to the limit, you may find that a 15-turn 540 from one brand may cause brown-outs, whereas another might be just fine. Unfortunately it really is kind of a guessing game, and that's just for brushed motors. There's even more variation with brushless.

One thing to stay away from is some of the "ESC + motor" bundles on various online shopping platforms. Not all of them are bad, but the ones with very low turn brushed motors may not work correctly out of the box, since the motor spec is outside the ESC spec.

[cyclonecap 68]

1 hour ago, Jourduson said:

Rule of thumb: ESC Ampere continuous rating should be 30% higher than the motor Ampere rating without load. No manufacturer gives that motor rating.

Where has this rule of thumb come from? Many RC applications will have a no load current close to zero and a max current in the hundreds of amps. There are motor manufacturers who give safe maximum amp ratings but this is the safe limit for motor, not the maximum it can ever draw.

https://www.arrmaforum.com/threads/speed-runners-reading-castle-data-logs-and-esc-settings.37182/ ESC data logs

https://www.banggood.com/SURPASS-Hobby-C3542-1000KV-or-1250KV-or-1450KV-Outrunner-Brushless-Motor-for-RC-Airplane-Fixed-wing-EDF-Ducted-Fan-Unit-p-1615378.html?akmClientCountry=GB&cur_warehouse=CN&ID=517699 Motor with max current ratings.

[alvinlwh 7226]

I had seen someone using 8.4v to calculate the RPM of a motor with 2S lipo while using 7.2V for 6S Nimh to sneak in a greater advantage. Wasn't noticeable until i did some reverse calculation. 🤷‍♂️

[Jourduson 35]

15 hours ago, cyclonecap said:

Where has this rule of thumb come from? Many RC applications will have a no load current close to zero and a max current in the hundreds of amps. There are motor manufacturers who give safe maximum amp ratings but this is the safe limit for motor, not the maximum it can ever draw.

https://www.arrmaforum.com/threads/speed-runners-reading-castle-data-logs-and-esc-settings.37182/ ESC data logs

https://www.banggood.com/SURPASS-Hobby-C3542-1000KV-or-1250KV-or-1450KV-Outrunner-Brushless-Motor-for-RC-Airplane-Fixed-wing-EDF-Ducted-Fan-Unit-p-1615378.html?akmClientCountry=GB&cur_warehouse=CN&ID=517699 Motor with max current ratings.

Not sure where I read the 30% rule of thumb, but it makes sense to me. Give any motor a good ESC/battery combination that can deliver effortlessly and you have a very happy motor when geard properly for the specific type of driving.

I'm also an audio engineer and no matter what the speaker Watt ratings are, I always recommend amp ratings in Watts way above them, to be able to handle transient peaks cleanly. The efficiency rating of the speaker actually tells me more on what kind of amp power will be needed.

But thanks for the Arrma link, it's very informative.

[alvinlwh 7226]

TBH, with the rather limited range of brushed motors you can get these days, it is unlikely you will go wrong with a HW1060/1080. That ESC will work with almost anything you can commonly buy today.

As for specs, here is a spreadsheet I made a while ago, any use to you? 

 

[Jourduson 35]

9 hours ago, alvinlwh said:

TBH, with the rather limited range of brushed motors you can get these days, it is unlikely you will go wrong with a HW1060/1080. That ESC will work with almost anything you can commonly buy today.

As for specs, here is a spreadsheet I made a while ago, any use to you? 

 

That is a very good job you did with this spreadsheet. Wish the manufacturers would publish lists like this of their motors.

You can bet on it, that they have all such data and more on each motor tucked away in a steel chest of drawers somwhere. Well, maybe I've been spoiled in the past.

But big cheers for the spreadsheet. I've been using hobbwing for the brushless builds and have started using the 1060 for brushed with additional external capacitors in the supply line after seeing the 1060 go haywire in combination with a super stock BZ 23T. The standard Tamiya 540 tin can had worked perfectly. 

[alvinlwh 7226]

1 minute ago, Jourduson said:

seeing the 1060 go haywire in combination with a super stock BZ 23T

I have heard of that but never seen it myself. I suspect it could be the earlier batch from a few years ago that had this problem. I even use mine on a dual silver cans setup.

Another ESC you can try, the Radiolink Cool 9030. Claims to be 90A, but what I like most is it's 7.5v BEC, meaning I can use HV servos. Oh, it can also take 4S, if you are into that kind of thing.

[Jourduson 35]

On 8/7/2024 at 4:55 PM, El Gecko said:

I agree, it is completely frustrating! Especially when looking for a motor with "more torque" than your current motor, it's not an easy spec to find. And yes, amp and torque ratings on motors would help a lot!

But in the meantime the best we can do is what they give us. Most ESCs have a list of specs for certain battery and motor combinations. Such as: don't go below a 15-turn 540-size motor with a 7.2V NiMH battery, or don't go below a 12t 550 motor with a 7.4V (2S) Lipo battery. Some are limited by battery size as well, usually topping out at either 2S (7.4V) or 3S (11.1V).

If you know the turn count of the motor you'd like to use in a particular car, you just need to find an ESC with specs that work with the motor and battery you have in mind (most here use the Hobbywing 1060 or similar clones). Also you'd want to match the type of battery connector on the ESC to whatever battery you'd like to use.

The specs don't cover all cases though, since different motors from different brands may have different amp ratings, even with the same turn counts. So if you're close to the limit, you may find that a 15-turn 540 from one brand may cause brown-outs, whereas another might be just fine. Unfortunately it really is kind of a guessing game, and that's just for brushed motors. There's even more variation with brushless.

One thing to stay away from is some of the "ESC + motor" bundles on various online shopping platforms. Not all of them are bad, but the ones with very low turn brushed motors may not work correctly out of the box, since the motor spec is outside the ESC spec.

Refering to your comment on connectors, I solder all the wiring, battery to ESC, ESC to motor to the needed lengths and use 4 and 5mm gold plated bullits for minimal resistance. First time I saw the Tamiya battery connection I thought "this ain't good".

[Jourduson 35]

2 minutes ago, alvinlwh said:

I have heard of that but never seen it myself. I suspect it could be the earlier batch from a few years ago that had this problem. I even use mine on a dual silver cans setup.

Another ESC you can try, the Radiolink Cool 9030. Claims to be 90A, but what I like most is it's 7.5v BEC, meaning I can use HV servos. Oh, it can also take 4S, if you are into that kind of thing.

Yeah, some have had problems, some do perfectly fine. I kind of enjoy adding capacitors just like when I used to build power amps. Big powerful transformer, oversized solid state rectifiers and capacitor banks as big as possible to feed a sweet little class A amp.

[Gun Slinger 393 164]

43 minutes ago, alvinlwh said:

I have heard of that but never seen it myself. I suspect it could be the earlier batch from a few years ago that had this problem. I even use mine on a dual silver cans setup.

Another ESC you can try, the Radiolink Cool 9030. Claims to be 90A, but what I like most is it's 7.5v BEC, meaning I can use HV servos. Oh, it can also take 4S, if you are into that kind of thing.

I have the 1060 in a mantaray that I put a SSBZ in that my son uses as I don’t mind him damaging it too much and honestly that thing gets no maintenance and just gets a charged battery and keeps running and running! He uses 4800 nimh batteries in it

GS

[Jourduson 35]

On 8/7/2024 at 3:31 PM, Jourduson said:

Hello every one, I'm new to this club, and have just begun building/driving rc buggies last year. I'm into Lego Tecnic too and have come to realise that the Lego community has a much better technical documentation of the Lego compatible motors than many of the manufacturers. All the data is standardised for comparability at one glance, especially amperes, rpm and torque in Nm at 6V and 7,2V.

I miss this consistency. Also some manufacturers give practically no information on their motors almost as if it were a big secret.

Rule of thumb: ESC Ampere continuous rating should be 30% higher than the motor Ampere rating without load. No manufacturer gives that motor rating.

If all this data were standardised as like in the steel industry, which I worked in for several decades, life would be a lot easier when looking for specific combinations.

How do you as a community go about choosing ESC/motor combinations?

Cheers!

 

 

I've just come across a good example of no info, no specs with Kyosho. As much as I like Kyosho, I think this example is going a bit too far, especially considering their asking price.

The way to do it is HobbyWing for example.

[alvinlwh 7226]

53 minutes ago, Jourduson said:

I've just come across a good example of no info, no specs with Kyosho. 

Those in the picture are brushless, quite different from the brushed chart I posted. Here is a brushless chart I made from gathering data from various sources. 

i don't think I ever seen torque listed for brushless motors.

[Jourduson 35]

I truly admire the work and effort you put in to those listings.

I suspect that torque is not specified for brushless motors, because of the close interaction with the ESC, especially when sensored. All depending on the type of ESC and it's settings the torque becomes a variable. One would have to set a testing standard with fixed parameters for comparability.

[alvinlwh 7226]

2 hours ago, Jourduson said:

I truly admire the work and effort you put in to those listings.

I suspect that torque is not specified for brushless motors, because of the close interaction with the ESC, especially when sensored. All depending on the type of ESC and it's settings the torque becomes a variable. One would have to set a testing standard with fixed parameters for comparability.

I made such list because, like you, I work with numbers. I kept getting told brushless are 'better' without getting any concrete measurements to prove it is 'better'. As you can see, the only measurable number is Kv and that is no better than brushed. If anything, one needs to get to around 9.5 - 8.5T to get similar Kv as the SS motors. On limited gearing Tamiyas (like the DT), they are just not worth it.

However, I am still experimenting with this mysterious torque of the brushless landscape, which is why I only install my brushless systems in 'free gearing' chassis, usually not Tamiya ones.

Those charts are just a starting point and is not the answer to absolutely everything you may want to know.

[Jourduson 35]

That's exactly the point. The data is here to help one make a short list what motors might work with a specific car and what one wants to achieve. In the end it's personal preferences and gearing possibilities that make the decision.

I decide on brushed or brushless depending on the buggy and what I want to achieve.

My DT-03, Buggy Champ and Fighting Buggy are brushed because I wanted to keep them simple and fun.

The SandMaster 2.0 is for the girls to play with: 1060 with Sport Tuned on Nimh.

Whereas I went all out on my BBX, Ultima, and Optima Turbo/Javelin with Hobbywing brushless combos, and all three can handle the power. 

The Tomahawk is also a HobbyWing brushless combo, but less Kv.

Because HobbyWing are generous with the data and the quality seems to be good, my begginer instincts went with them. Also they have ESCs and motors which the wiring can be individually soldered/taylored.

Edited August 10 by Jourduson
Grammar typo

[Jourduson 35]

On 8/10/2024 at 9:40 AM, alvinlwh said:

Those in the picture are brushless, quite different from the brushed chart I posted. Here is a brushless chart I made from gathering data from various sources. 

i don't think I ever seen torque listed for brushless motors.

Hi alvinlwh

Here's a link I found that might interest you.

https://ibtinc.com/difference-between-brushed-brushless-motors/#:~:text=significantly better performance.-,Torque,torque versus brushed motor torque.

 

Cheers!

[BuggyGuy 1140]

I find this quite interesting coming at this from a racer point of view.

We have most new drivers who join (running 1/10th buggy) to start with an 8.5T brushless with a 60% throttle limit for the first week or so. Then they gradually increase the throttle limit and then up the timing when they are comfortable.

Nearly everyone who's been racing for a few months ends up with a 6.5T with various levels of boost and turbo to suit their style.

All UK buggy racing (none vintage) is done with brushless sensored motors and I doubt you'd ever see much more than a 5.5T / 6.5T in 4WD and 6.5T / 7.5T in 2WD

[ozace 21]

On 8/8/2024 at 6:25 PM, alvinlwh said:

TBH, with the rather limited range of brushed motors you can get these days, it is unlikely you will go wrong with a HW1060/1080. That ESC will work with almost anything you can commonly buy today.

As for specs, here is a spreadsheet I made a while ago, any use to you? 

i just tested some of my motors all new using an old apex motor tester.

silver cans (tested many) 2200kv

formula tuned 1750kv

lightly tuned 1950kv

dirt tuned 2075kv

gt 2250kv

ugt 2325kv

rz 3375kv

tz 3425kv

bz 3500kv

On 8/8/2024 at 6:25 PM, alvinlwh said:

 

 

[alvinlwh 7226]

12 minutes ago, ozace said:

i just tested some of my motors all new using an old apex motor tester.

silver cans (tested many) 2200kv

Mine is just numbers obtained through various sources but I had long suspectd that the silver can is faster than the numbers I managed to find as many times, the actual speed of my car is higher than what my gear ratio calculator comes up with.

Base on your tested numbers, it seem to be as fast as a GT.

[Jourduson 35]

It looks as if Tamiya is overachieving its specs to be on the safe side. I would like to see the numbers of brushed 540 motors produced, it must be phenomenal. When looking at the silver can I can just envision the raw sheet of steel being cut, the axel wire coming off the coil for straightening, cutting, first heating, second straightening, polishing ......

[Wooders28 4910]

Motors are rated in 'Turns' .

The thicker the wire ,the more electricity can flow, the more powerful the motor is.

The thicker the wire, the less 'Turns' of wire can be wound in the space given, so less Turns = more current = faster motor.

But something I don't think the Lego motors won't have (I'm guessing, not touched a Lego motor for nearly 40yrs...😬), is timing?

You'll notice on the data @alvinlwh nicely collected, there are motors with the same 'Turns' , but different RPM ratings and loads These motors (aswell as different brushes and maybe bearings instead of bushes), have different timing. On modified motors, you can alter the timing yourself, which was great back in the old Nicad days, as you could adjusting the timing ,so you got speed, but also enough battery to last the race (with modern Lipo / liHv, that's just not a consideration these days).

With the Tamiya sealed can timed motors (torque tuned etc), they are directional, they go faster one way, than the other, so no use for the likes of the 'Clod Buster ' which requires 2 motors, going different rotations.

 

With brushless, the cheap sensorless use 'KV' which is RPM per volt, but really just gives you an idea , as some cheap ones just fall off a cliff, when you ask them to do any work.

Sensored brushless are measured in Turns, but as there's no end bell to turn, they alter the timing electronically via the esc, with a 'sensor' knowing the motor position in degrees. These motors will give different current ratings and rpm (kv) depending on the timing (Boost) and the full throttle timing (Turbo).

This vid of a 13.5t motor on the dyno, testing various timing ,gives you an idea.

 

 

On 8/7/2024 at 4:26 PM, alvinlwh said:

I had seen someone using 8.4v to calculate the RPM of a motor with 2S lipo while using 7.2V for 6S Nimh to sneak in a greater advantage. Wasn't noticeable until i did some reverse calculation. 🤷‍♂️

Both 2s lipo and 6s Nimh are 8.4v fully charged (liHv CAN goto 4.35v per cell, so 8.7v on 2s) , so not sure why 7.2v and 7.4v are used tbh (yeah I know it's 'nominal' voltage, but people rarely use a nominally charged battery..🤷‍♂️) 

[Wooders28 4910]

Some manufacturers give some data on the side of the box, this was a 4.5t motor box I got.

 

 

 I use this as a rough guide (as above, you can add timing on a sensored motor, and also double its KV)

 

From when stock motor racing was a thing (was meant to keep it easy and cheap, but to win, you bought a dozen + motors, did all the reverse break in etc, picked the fastest one, but some used to pull the armature out, and swap it for a lower turn or cheat as its known, which meant organisers had to check each car etc etc. Turned into a hassle and expensive, so now just race whatever)

 

 

[Jourduson 35]

28 minutes ago, Wooders28 said:

29 minutes ago, Wooders28 said:

But something I don't think the Lego motors won't have (I'm guessing, not touched a Lego motor for nearly 40yrs...😬), is timing?

Lego motors were never tunable, but the older ones had much more clout and no protective circuits. Now, due to third party damage regulations for toys, the present motors have at least a thermal resistor in them. After a couple of minutes the motor slows down.

There are manufacturers like BuWizz that offer complete rc solutions for Lego.

I have a small collection of old not 'castrated' motors for my Lego MOCs. 😁