Comparative claims in controlled testing

[quote=“Karmannghiagirl, post:15, topic:2210”] Why do you think automotive racing teams spend so much time with their motors on dynos before they even put them in the car?[/quote]

They select the winner of the race based on the car that crossed the line first…right?.. not necessarily based on the engine that has the best dyno performance that day… They must perform the best in the race to win.

This is how I feel about eboards too. Let’s see them perform, side-by-side… Much easier than a lab test.

Of course once you have the winner maybe then us nerds will need some lab test to help analyse exactly how it can beat the others… but we a splitting hairs on this.

Not directly because of that, but because of the way that you talk to people on the forum, and how instead of listening to reason and being open to other ideas you call people who disagree with you:

Probably, if the company has good reviews and I trust them. Specifications are there for a reason. They tell you what a product can and can’t do.

I do want to see it do that. but if i have two board that have similar videos of people going up hills, then those videos are not very helpful :wink:

nope, going to build my own.

lol, u mad bro?

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@onloop, I invite you to erase the worthless specs and numbers from your Raptor product page and just replace with video links.

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I am not saying this is right or wrong, but I have to agree within magnetic terminology maximum torque is produced in a near stall position of the rotor. However necessary the fact that we are having this hill grade discussions is because they doesn’t seems to work that way when being put together with an esc. Otherwise no one would have a problem starting standstill on a hill / ride it to the slowest possible speed. I really believe that the rated speed is the moment where the motor could provide the maximum torque in real conditions.

One way of another speaking about Tesla, they stated in their website that they are using 3 phase AC induction motor. They are not normal brushless dc motor. Their motor runs without magnets, so it doesnt depend on motor magnets strength to output torque, pure mega current draw from their battery packs.

Increase in torque means increase in current draw or how much current it could deliver. The motor cogs (pulsing) because the ESC can’t determine which phase it should power the motor. But I also doubt that sensored motor have 0 cogs at low speed (never tested it).


Btw please stop discussing about numbers vs video. This is more destructive rather than educative. They do need each other. You can have all the numbers but without no one ever made a single video / proof it’s ever rolling its meaningless. Same to video, without number people can’t compare or relate to other builds.

The answer to the question of Comparative controlled testing is who is able, would like and or be able to do just that. Without it the eboard community can live without it, us making whole bunch of this is a proof that we can build without numbers. As for the same time, we need this forum because we can’t find, relate and be exactly convinced that the selections of parts we bought does work on the environment we would like to ride

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From my own experience, motors seem to peak in output at about 70% to 80% of the max rpm. Performance at zero is insignificant to me since I always give a good healthy kick before mashing the throttle but I do feel a definite surge when nearing the top speed on my boards. Smaller motors seem to surge more than their larger counterparts. Maybe the larger motors would give a more pronounced boost if the were more heavily loaded?

I read a motor will perform most efficiently at roughly 80% rpm of kv x volts. Maybe it’s efficient because it has the most power and therefore doesn’t have to add more amps to compensate.

This is not really a discussion about basic specs though… you wanted to discuss testing various brands of esk8 using dynos to get a set of data results.

Nominal voltage, watt hours, motor kv, wheel size, motor size, peak watts/amps etc… this info is not scientific evidence of the performance.

My point here is… why invest time and money into doing these scientific tests using dynos when you can grab two boards and walk into the street and have your answers within a matter of minutes.

Do you guys actually own any electric skateboards? Be honest.

So you don’t have an electric skateboard? What ones have you actually tested/used?

ALSO, please try to refrain from directly insulting people, especially the forum owner.

I have a dead board but 120 motors. “Nominal voltage, watt hours, motor kv, wheel size, motor size, peak watts/amps etc… this info is not scientific evidence of the performance”. Yes it is.

when does a motor produce the most torque and why. People are disagreeing. I though the sole determinant was the steel stator and how big it’s teeth are, bigger be less likely to magnetically saturate. Torque equates to magnetism. Will more teeth make more torque or bigger teeth.:laughing: many small or few big. I wouldn’t have thought it was speed dependent.

Heheh, @Karmannghiagirl he’s got a point! :smirk:

I’d consider toning down the snark. I personally have marveled sometimes at how welcoming @onloop has been of teardowns and critiques of his creations. It’s a big part of why I bought his product, and am happy with the result.

Cheerio,

  • Fred

Onloop is a tear-down critique master of his own creations:grinning:

I couldn’t help it. He said it

Basic specs written on a page is not evidence of performance!

Emperical evidence must be observable & undeniable.

For example. Max top speed based on a paper calculation of the above specs will not actually be what happens in the real world…

Unless of course you factor every single variable into your equation Some of the variables include.

  1. Wind resistance
  2. Rolling resistance
  3. Wheel hardness
  4. Temperature
  5. Esc effecientcy
  6. Motor effecientcy
  7. Mechanical losses
  8. Motor core losses
  9. Control algorithms
  10. Field weakening characteristics.
  11. Bearing friction losses.
  12. Rider stance
  13. Rider height.
  14. Rider width. … … …

The list goes on and on… no one is going to perform this level of scientific study anytime soon… Unless maybe someone on here does a thesis on electric skateboard performance for their degree in electrical engineering. It’s probably not going to happen…

So simply stand on the board and ride it as fast as it will go and check your speed. Now get the other brand of board and repeat the test.

Its really simple… step away from the computer and ride!

I like numbers too! Very useful when making comparisons. In stand alone tests though they almost never match up . I think Jason’s point is you can see successes and failures in video comparisons. Also, you can easily call bullshit on obvious editing. Not so with spec sheets.

I am sorry if I have been too brash in my comments. I can get overly passionate about things sometimes.

(to be fair, I feel like I was not the only one being snarky about this)

While it is true that I do not have an esk8 yet, I don’t think that should exclude me from this discussion.

While it is not direct evidence of how a board will perform, it can definitely be used to compare multiple boards.

But if all the boards are tested the same way, in the same conditions (using a dyno), the other variables don’t matter as they will apply to all of them. So you can have one board that has a rated top speed of 20mph and another with a rating of 30mph. 99% of the time, if you put both of them in the same conditions, the one with a rating of 30mph should go faster since all those other variables are acting on them in the same way.

Not all of us can afford to drop thousands buying and testing different boards. For people like me who are still trying to save up money to buy/build one, testing like what is being discussed here can help us make decisions on what parts/board will fit our requirements the best.

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is it true that “basic specs written on a page is not evidence of performance” of your motors? Is that what youre arguing.

Totally agree on this, but if you spend some time reading some members post. It’s pretty clear if you aim lower price, you need to get single drive kit, motor from HK, cheap TX RX and lipo stacking. The cheapest possible solution with the most output you can possibly get. However on those part make sure you have one best part to begin with, ie VESC / motor. So next time you have money, you can upgrade. One solid thing I have to say is that eBoard is not cheap. You can’t just force your self owning something you can’t afford. The chances people do DIY is they want to proof something, make something better or make something happen. If you aim to get cheap, I suggest get a ready made board from alibaba / aliexpress with 1 year warranty and upgrading from there. First you have a working board, second still upgradeable within your budget.

Numbers and real performance can’t go without each other. One prefer numbers, one prefer real life condition. This discussion feels very childishly finger pointing stupid while the truth is that both need to exist, just for the sake of ego.

It’s time to make some popcorn and keep reading how it goes lol.

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Sorry, you are wrong. You need to test in the real world. lab performance doesn’t translate into real-world results.

If a board, or just the motor, is attached to a dyno how do you accurately simulate load? I want to know the result with a rider onboard not just a paper result of an unloaded test. Also, the load is variable depending on incline, wind etc

In theory, a tiny little 42mm motor could spin at the same RPM & Perhaps deliver a similar torque curve as a much larger 63mm motor. So to get meaningful results your dyno will need a load generator that simulates rider weight, also it needs to somehow introduce a slight increase in load as speed increases to simulate wind resistance.

The easiest option is to establish a standard real world test, like the 1/4 mile sprint for cars… e.g. 100kg rider weight, 100m sprint from stationary start. This is easy to record on video. Every supplier can replicate it fairly easy with little expense, its fairly obvious to the viewer if it has been faked, it can be replicated by anyone. It’s testing torque & top speed performance.

Hill climbing is what I am personally interested in, none of these mainstream brands seem keen to show us hill climbing performance… come on inboard & mellow… one video is all I ask.

Like I said at the beginning… real world tests are better… everyone needs to go & ride.

if you don’t agree with my statement that’s fine too…

Hey, I’ll be doing real world testing and comparisons as soon as get my raptor dual shipped. I have an inboard M1 on the way, and already own a boosted dual plus.

The video will include objective tests in controlled conditions (like max speed, range, hill climbing ability, and acceleration), and subjective tests (feel, fit and finish, ride quality, durability, design). I’ll also include things like customer service.

So all this meaningless argument from your computers is not necessary.

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There are ways. That’s what dyno’s are for. SAE Standards for Mobility Knowledge and Solutions Wind? Non-consistent inclines? These variables are exactly WHY real world testing is inherently unreliable in comparisons. What to do with them? Eliminate them, so they don’t adulterate the results.

How do you quality check your products, Onloop? Real world? Is a defect going to slip through because there was a strong back wind, or you decided to take the left side of the hill with the helpful depression, instead of the right side because a car happened by that day?

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I just realized something: Onloop, you don’t actually know what a dyno is, do you?

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