Don’t think so. The way I imagine is, if this secondary button is pressed, it just restricts the maximum throttle to the maximum efficiency line, so by going full throttle you are at the maximum efficiency point, just ease on it to maintain the speed as always
Some more logic is needed so that when you release the secondary button it doesn’t suddenly goes full throttle
I think 90kv with 1:5.5 gear ratio and twice the voltage would have higher efficiency and a bit more acceleration than either option.
24s is a little too much for me 
!!! But yeah the acceleration would be insane!
Very nice info Pedrodemio! You seem to have very great knowledge! So lowering kv is nice when you ride fast on streets without braking and accelerating. So it would not be great for a mountainboard that goes up and down hills, gets stuck in mud, etc.
You say that resistive losses is 1.5% total energy used and core losses is 3.28%. To me that is pretty small. Do you have an idea how worst it could be for a mountain board running the setup I mentionned? 12s, 6374 90kv, 1:2.6 ratio, 200mm wheels. Could it get to let’s say 15% total energy lost because of the low kv and low gear ratio? Or do you think it will always stay under 15% with good motors like the maytechs?
Also do you think going 16s or 18s instead of 12s with also an higher ratio like 1:4 would reduce the losses?
Thank you!
We need more people doing real world testing!! Then more people could answer these questions and not be asking!
Good on ya for trying to figure it out before though. 
Yeah, but it’s important to not generalize. This scenario is where a good hub or direct drive would shine. And following that, you can design a direct drive to perform extremely well on those difficult conditions, in fact this is what I did
In fact they are low, this is probably due to my chill riding style, but I don’t think it will be that bad in any kind of common setup, this also means that the gains you can have by optimizing your board could be easily be considered insignificant if you just pumped your tires a bit more (testing the is at the moment) or by decreasing your top speed by 5 km/h
One thing is import to note, we have been talking about efficiency, but this is not always the ultimate goal, for example, the setup with higher Kv and greatest reduction will almost always be capable of more power if the rest of the electrical system is capable of delivering
This comes from a fundamental point that brushless motor have a torque limit, and not a power limit. The heat due to resistive losses is always proportional to torque, doesn’t matter what Kv it’s wound to as long as the amount of copper in it is the same
Take your 190 Kv, let’s say that when producing 3 N.m of torque it has 100 W of resistive losses. If you take a 90 Kv version of it and drive it with the current needed to produce 3 N.m, it heats losses will be the exactly 100 W
The deal with Kv is that by respecting the same hypothetical 3 N.m limit (that’s around 60 A on a 190 Kv motor) you can have the 190 Kv producing 3 N.m at almost double the rpm, and since power is torque times angular speed, you now have almost double the power at the same resistive losses
Where things get complicated is when you start considering core losses and whole system efficiency, and this is where riding style come in, no way to calculate without riding data
Depends, only matters if you change the Kv in theory. If you don’t change anything, just the ESC and battery voltage, and limit the top speed to the same as 12S system, it would be very similar, maybe a bit worse since HV ESCs have higher internal resistance in most cases
What makes sense in going higher voltage is if your ESC is getting too hot and you want to push it further, you take a lower Kv motor and drive it with more voltage, by doing that you need less motor current for the same torque, so the ESC will heat up less
Hope I didn’t confuse you more, it’s not as simple and there is no single answer, if you are designing the whole system it’s normal no go in loop a few times, changing things everywhere until it’s all good
Oh forgot to show the left motor has the open back with mesh design.
If they are the same or really close, yeah if things getting inside is not an issue, I’m going the other way since to increase reliability and decrease the grinding noise due to sand
By the same I mean Kv, phase resistance and core losses, if it’s not the same it gets harder to say since it can have less losses and not get that hot even being somewhat closed
I had misspoken earlier, motor losses quadruple with 90kv & 1:2.6, but yes 90kv and 1:5.5 with higher voltage reduces esc heating to 1/4. With 12s the 190kv & 1:5.5 seems the best option.
On the bldc tool if u look at the resistance and the kv you can compare what will put out more heat for an amount of torque. You can also compare the iron losses just spinning them at the same high speed and seeing which takes more current. the open motor’s cooling could reduce the wire temp and it’s subsequent increase in resistance
Thank you so much for your replies to all my questions! Where did you learn all that stuff? Online course for electricity basics applied to esk8 would be nice!! When will you launch Pedrodemio Academy ?
Thanks man
Basically years or being interest in it and doing my final eng. thesis a motor design
The fundamentals of what happening in our motors is not that complicated if you have a basic notion of electricity and mechanics, how they come together are also not complicated, but takes time to fully digest everything and make it click
If you want to dig a bit at it, I highly recommend this book, you can skip all the parts where it gets too technical, but there are some overview sections that that are really good, it’s been my bible for the past 2+ years
Once events start happening again I would gladly make a crash course on motors for those who want
I wonder if the weight of a gear reduction system was replaced by a heavier 34kv direct drive motor with lower kv & lower resistance so the board weighs the same if it could actually be more efficient… ie replacing nearly the entire weight of the gear reduction with additional copper windings, for example.
Something something about losses from having such a huge motor when it isn’t fully utilized. Flux and stuff…
I have no idea, would be good to see a comparison between hub motors with different copper fill at the same wheel size and stuff.
I feel like more copper is going to be moar better unless you consider cost or weight in the calculations. But idk
For prolonged use factoring in temperature yes, but at a fixed temp I feel too large of a motor will suck up some of the energy and not transfer it into torque. Perhaps this only would happen far beyond our size requirements.
Currently have a mental image of an Earth-sized stator driving a 76mm Ahmyo Akasha wheel.
This is where you start to get an idea of what a huge task and pain in the but is to optimize an entire system, every change everywhere influences all the rest
I will look up how heavy my DD motor design is compared to the current belt setup I run. Both should have the same efficiency (theoretical for now), but the stator and a big chunk of steel that don’t help in being light
