Torque curves and response

General Discussion
#1

Mellow published their torque curve a while back, and I didn’t really understand what having a flat curve (up till rated speed) really meant. You know how you have to brace yourself when hit the throttle? When I did a testride of the board, even up near 35 km/h, I’d get that exact same kick. It was a bit like riding a bucking bronco.

Mellow torque curve: https://www.kickstarter.com/projects/1800147378/mellow-the-electric-drive-that-fits-under-every-sk/posts/1352482?lang=de

I’ve only ridden a Yuneec E-go (completely mushy acceleration the faster you go) and the Mellow. How do your DIY builds deliver acceleration as rpm’s increase to maximum? Are there motors out there with better torque curves than others? Is such a thing even measured or specified? Thanks!

I like high speeds, but punchy acceleration is what really brings the fun.

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#2

On my 10S twin VESC / 6355 R-SPEC set up, it doesn’t matter how fast you’re already going. You have to stay easy when increasing speed or it will launch into hyperspace.

My 6S Favourite 120Amp / NTM 270 5060 setup acceleration is kind of mushy on the top end, but you can still feel a little kick. I think the pack is to blame for that though because on a higher C rated pack it was only slightly less punchy than my 10S.

#3

Great question @Calhoun… It seems like this was once a matter of which motor\esc setup someone had, with the gearing\reduction ratio playing a big role. Now, with VESC, there are a lot more parameters to work with and that’s where I’ve don’t the most tinkering. I use the VESC “Startup boost” parameter to dial in the feel of startup torque. You can really adjust the “feeling” of the ride w vesc. I like to keep the torque on the strongish side but cap max RPMS so that I don’t get thrown! Agree that acceleration is where the fun is!

#4

Plenty of punch can be had with car ESC’s if that is what you are after. You bagged on the VESC a little in another thread while you were hyping the mellow drive but what makes the VESC so great is it allows us to control how much punch our boards have.

#5

Thanks to all three responses above - the most interesting thing I found about them was that you seemed to say that torque performance can be tweaked by the VESC. I had assumed it is a quality inherent to the motor, but that’s pretty silly - sort of like combustion engines…how you feed the thing is definitely critical to how it will perform.

Does this mean that all BLDC motors reach the same maximum torque performance if control settings are optimized?

#6

You explain torque curve like you can handle 100% full throttle from the get go. These tiny motors are powerful.

An E-go is definitely limited. A Mellowboard is definitely limited. It’s basically no comparison.

You need to go DIY already talking about torque curve. It won’t make a difference if you can’t even stay on the board.

Granted the actual data would be nice to have… but is it needed?

To answer your questions… There are different motors and different motors provide more or less power, more torque or less torque. There are different ESC’s, different battery voltages and they differ in results.

I’d love to see a mellowboard or E-go try and tackle 15-20x 20-30% inclines back to back and not burn up.

#7

The motors we typically use have too much power for most people. The output of the motor is mostly due to the diameter and length of the stator. It is best to have a motor that has much more power than is actually needed so you do not have to work it as hard as a motor that can “just” get the job done. Unfortunately having a very powerful motor with no way of detuning makes it very hard to control, a kind of all or nothing throttle control. Seeing you ride the mellow reminded me of the earlier days when everyone was using car esc’s. It actually sounds like they are using a 12s opto esc.

#8

The torque generated by a brushless DC motor is proportional to the current times the number of turns. For a given setup the number of turns doesn’t change so it suffices to log the motor current against the motor rpm to get your torque curve. I think.

I would love to hear how Mellow plotted their curve.

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#9

LOL it wasn’t that long ago. I’ve only been doing this for about two years and i have among my collection 2 dead dual car ESCs and a pair of Favs driving my dual motor 6S. I may buy DIY’s 12S as a holdover while waiting on these VESCs from Enertion. Car ESCs are still a solid option for people who don’t want to wait a month or three for a VESC.

#10

Exactly why I went with Torqueboards 6s ESC. I wanted to try the VESC, but I also wanted to ride asap, and get a first successful build under my belt. I do like the plug and play aspect too, and may also go the TB 12s ESC in the meantime. I wish they weren’t quite so expensive though, especially compared to most VESC’s. I’d probably already have gotten one if they were around $100.

#11

Yeah I should have said last year ;). Before I started making the VESC everyone was doubtful on it’s reliability and it was a big gamble to purchase one so your best option was an ezrun or the 12s esc from DIY. All it needed was was quality manufacturing with attention to detail.

#12

agreed. It needed the love people like you could give it. And now we see it blooming into maturity, and everyone wants it. Much like the Olsen twins did.

#13

It has been a great experience and I feel privileged to be part of it. Great things are on the horizon for eboarding. I hope we see something similar to moto gp develops in the years to come.

I love competition! I think we will see much more in regard to performance and numbers when a solid circuit develops. There is a dh/freeride event going down about 2 hours away this weekend but I can’t go, need to get orders out! I was hoping to bring my latest sled and let some of the talent hit the course and get some good footage but it will have to wait.

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#14

I always forget that you guys have no size, weight or power limits and overengineer. Of course no one will care about torque response if the max is way above what the human body can take anyway. :slight_smile:

My prerequisite for an e-skate has always been extreme portability. I think the unconscious reason people thought the hoverboard was great in Back to Future was not only that it floated, but that it was small and light as a normal skateboard.

If I was going to make a build that is under 6 kg, what configuration would I use to get the performance @torqueboards is talking about?

#15

Sorry, I didn’t mean to seem to. “Vaunted” is good… My point was that Mellow just decided it didn’t meet their needs, so they made their own. I don’t build my own boards but have read enough to see that Vedder’s ESC is a huge resource to the DIY community.

I do admit that your posts about it shutting down and rebooting at speed were a bit frightening though.

#16

The shut down was due to the bms over current. But honestly the mellow board has yet to prove itself we will see how it performs when it eventually starts production. I can tell you based on the videos that they used an off the shelf esc either that or they reversed engineered one. Nothing special about uncontrollable torque. They really should take a second look at using th VESC. It will make their system much more user friendly.

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#17

LOL dude it’s the whole point of this forum basically. This is where you come to learn how to take a 200 pound man up steep hills at 40mph on a skateboard every day to work for years on end.

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#18

@longhairedboy Totally agree! I used to doubt like hell upon the start as it cost alot to make an eboard. It’s not a common type of vehicle, so build and performance are very unknown with big chance it could fail go wrong and abandoned.

@Calhoun To be honest man you know alot about mechanical and electrical and construction, which is good for you to begin with. However necessary if you don’t have an eboard or part of an engineering team of an eboard or you never build an eboard before, do not critize us that we don’t do the numbers or we didn’t do it correctly. If I build something, it’s up to me what I want to do and say and I will not take an opinion or criticism seriously if you haven’t proof your claims neither purchasing things from members here. If seeking an absolute numbers satisfy you, then please wait patiently for melow boards to arrive. And for me building an eboard is all about the development. Trust me when you build one you won’t stop upgrading. There will be a point where things will become much clearer, just need to be patient about it.

PS: do not over criticize, speak of solutions and proof.

If your claims is true that we have no size, weight or power limits and overengineer, than why are you here? you will learn things the wrong way. But as far as I could browse the web, this is the best place with some of the best Home Grade DIY eboard that builds crazy over the head specifications. The rest aim for cheaper, efficiency, portability (speaks only for marketing selling point and not the real performance). I couldn’t say numbers because we do not have 1 thread with all of the details, but many who succeeds build their board here are very satisfied. The only numbers I think which is important is if your budget fits the build, upgrade, replacing broken pieces and the shipping cost.

Just take it easy, eboard is not a device that require detailed specs. I have build single belt drive 192kv motor with 24v that could climb 35 degree all the way to infinity like baws, it just need a few kick start. The reason why it can’t go 40 or more is not because the motor or esc are not capable, but the wheels are loosing traction. And if you consider building 5kg board, it will be loaded with a bunch of rubbish low spec setup. Even if your numbers even up, your wheels wont grip because its a variable that you havent mentioned yet.

#19

@laurnts, I didn’t criticize anything that I recall. I was looking for stats and numbers where I can get them ; if you don’t do it that way, who am I to say anything?