my calculations are in agreement with that estimated top speed, I came up with 35-38mph estimated top speed on flat ground and 73lbs peak thrust for the 83mm tires vs ~55mph and 46lbs peak thrust assuming upgraded 130mm tires (also assuming 50v bat, 60a battery & 60a motor current limits per motor, 2 motors, 85kv, 0.07ohm winding). ohmic heating at full throttle looks to be about 252w per motor @ 60a motor current.
@hummie whats the pricetag on these and can they be ran at 12s? im thinking of building a hub build for commuting
for sure can do 12s. almost any motor can do 12 or whatever really and the limit would be the esc being able to do it (as long as it doesnt go too fast for the bearings, which we dont do). there seems confusion about voltage of the BATTERY and what it does in a motor. it will not make your motor run cooler to run more voltage and actually the opposite. So unless you really will want to go over 30something miles per hour and instead will more likley be riding in the high 20s anyway, you will be more efficient, keeping the motor cooler and getting a bit better range, running 10s. In a power line in the sky or in the wiring for the board’s battery yes higher voltage will lead to better efficiency but not the motor. the esc converts the amps and volts that come from the battery into a different ratio for the motor and you can control that with both the motor and battery amp limits on the vesc. i didnt realize the motors went quite so fast on 12s as i never really checked… I always ride FOC which is a bit slower. @willpark16 is riding 83mm tires,…the new coming are actually 84mm so a hair faster. It would be worth going to 10s unless you really want that speed but then again…i rarely was at that speed and while doing some really long steep stuff the temp of the motors stays within what i’d consider an acceptable max temp. of 160f. the motors COULD go up to 300f as the magnets are good to that temp and the winding wire is good to 400f for thousands of hours, and some of the bearings have grease good for 300f…but the tire polyurethane is surely the weakest link. what temp it can do, you tell me!!! so far ive been really amazed by these prototype tires’ durability and ride quality.
130mm tire??? how bout a 90 or 97 next. but guys just ride these with the 84mm now and give it a bit of time and I said I’d get the bigger tires made and will. what’s going to have to happen is a kickstarter or some other way to get a large investment. Now i have just enough money for what we are getting and will be able to make a couple motors beyond but business is stuck really held back by not having…like 30,000$ for materials. all the money i raised in the past went to get these parts for 100 motors and about 70 are accounted for. So myself and @professor_shartsis and probably @evoheyax with some others will be quickly throwing together some kind of video and straight to kickstarter. Ive stopped taking orders for motors for the last couple weeks until everyone who paid gets theirs and want to spend time not selling but doing this video. If any of you have any experience or desire to be involved in making this kickstarter video lets talk when the tires come.
i just wrote aend again to hear whats up. last i understood it would be like 2 more weeks for the tires and will update you when i hear the latest.
But…
deckoz/pshaw experience throws everything out the window.
Wish I wasn’t late to the party. I’ll be waiting for that kickstarter. Hopefully there will be some early bird special. My hummie deck needs hummie hubs. Thanks for all the rad esk8 work.
i ran a comparison for 10S vs 12S… 60a motor limit 60a battery limit for both…
the electrical to mechanical conversion efficiency in the motor doesn’t seem to be affected (green line top left chart)… but you lose a few miles an hour of top speed with 10S.
system-wide it would appear you may lose a little bit of efficiency with 10S because, as seen in the bottom right chart, at 10S you have to draw a few more amps from the battery at all speeds to maintain the same 60a motor amp limit in the motor, and consequently you generate a bit of extra heat in the battery wires with 10S compared to 12S, lowering the system-wide efficiency.
real world who knows what was going on and hard to get a true test done but here’s a simulation with the only variable changed being the voltage. same speed. look at the bottom and it breaks it down
total system efficiency with the 10s is better and it ends with a lower motor temp. this is just a change of voltage first shot
this one here is an increase of kv and has similar results.
interestingly I did a second 12S vs 10S comparison with 60a motor limit and 30a battery limit (instead of 60a motor 60a battery)
in the new comparison you get higher motor efficiency with 10S above the speed that you hit the 30a battery limit because above this speed you get less motor current at the same 30a battery amps with 10S… and less motor current means less heat generated and consequently greater efficiency.
(notice the green line top left chart – motor electrical to mechanical conversion efficiency – gets a slight boost with 10S)
what i posted and @professor_shartsis posted show to disagree. i have more faith in the simulation i posted due to who made it, jason lee who owns endless sphere, and its widespread use, vs shartis’ which hasnt been through nearly the trials and oversight and it’s not as encompassing.
one thing that could be happening in personal experience showing more range with higher voltage is the cells are not being sucked for amps as much for the same performance and with less peak current draw a cell will produce more mah. if you suck a cell at its peak possible current it will produce less energy than if you were to discharge it at less current. so maybe with a lower discharge cell such as ion vs lipo, it would be even more advantageous to have higher voltage. but assuming a cell is not decreasing its total output due to this phenomena then the graph i posted should accurately reveal the range
@Hummie here’s all the formulas used (and verified)…
let’s take 50v @ 20mph from the graph (30a battery limit & 60a motor limit, 0.07ohm winding)
20mph @ 83mm diameter = 2057.30454rpm
2057.30454rpm / 85kv = 24.20358v back emf
50v * %55.91814 duty = 27.95907v effective voltage
((27.95907v effective voltage) - 24.20358v back emf) / 0.07ohm = 53.64984a motor current
27.95907v effective voltage * 53.64984a motor current = 1500w electrical watts
1500w electrical watts / 50v battery = 30a battery current
(53.64984a motor current)^2 * 0.07ohm = 201.48142w ohmic heating & copper loss
(2057.30454rpm * 2 * pi) / 60 = 215.440427 rad/sec angular velocity
60 / (2 * pi * 85kv) = 0.11234 newton meter torque per motor amp
0.11234 newton meter torque per motor amp * 53.64984a motor current = 6.02702 newton meter torque
6.02702 newton meter torque * 215.440427 rad/sec angular velocity = 1298.46376w mechanical watts
1298.46376w mechanical watts / 1500w electrical watts = %86.564 electrical to mechanical conversion efficiency
1298.46376w mechanical watts + 201.48142w ohmic heating & copper loss = 1500w electrical watts
if you can find an error in any of these please let me know.
Holy crappers what did I start lol
a shartis storm
heres another comparison at partial throttle which will be a bit different than the other graphs which had full throttle for the 10s and a bit reduced for the 12s to get the same speed. when able to go full throttle the switching in the esc is …not switching and more efficient. so here the difference between the two is less as theyre both at partial speed. the lower voltage is still wining in eff and somehow killing it in range.
@Hummie that chart I showed is both at full throttle… so what happens if you put both at 100% throttle for an apples to apples comparison (same speed and same throttle, different voltage)?
so youre saying change the kv then? how could they both be 100 throttle and same systems and motors and speed with diff voltage? at a reduced throttle youre losing eff in the esc
2 charts ago you posted a chart showing both at full throttle, and a 2% gain in efficiency for the 10S…
the last chart i posted at 20mph also shows a 2% gain in efficiency for 10S… so what I don’t understand is why do you say the charts don’t agree?
2 charts ago while it says 100 throttle…it cant be! unless it was a different kv motor how could they have the same speed with different voltage? … it must be at like 90 percent throttle or something to get the results and not show on the throttle settings
but as far as yours disagreeing…i thought that’s what you said. I cant read yours its so small!!
i said…
then you said…
your chart shows 2% gain in efficiency for 10S at full throttle:
this chart also shows 2% gain in efficiency with 10S at similar speed at full throttle:
in the first graph you posted you said you saw
shartsis’s 100 throttle means pulling the trigger all the way down. not at top speed, if you look at the table you see that 12s can reach higher speed. and I assume the 100 throttle different speed is calculated for instantaneous moment as suppose to be constant speed.