That data sure was statistically significant. I was concerned it wouldn’t be because of start/stops.
Efficiency falls off massively the faster you go
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Regarding methodology and the drag equation since it has to do with cross sectional area I imagine your size and stance will effect things but I can certainly feel the extra drag effect from the wind and standing vs crouching or reducing my profile vs flat chest forward seems to make a difference on extra windy days.
Air drag is exponential of speed, this is not news, what needs to happen is a realistic range estimation at real riding speeds on flat ground assuming no wind. As EPA rate MPG on cars, board range should be measured at a set speed, say 20mph, from full charge until it drops from that speed.
These extended range estimations of a board going 5mph down a slight incline for the next 200km is just useless.
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Agree about the instantaneous value being extrapolated not being realistic but imagine it is being done to try and emphasize the point and use the limited data available from the runs.
Regarding “standardization” of testing finding an open road with no intersections where I can just go 20mph consistently is pretty tough, I usually peak around 20mph and average 12mph on rides to the local convenience or grocery stores. 5mph vs 10mph vs 15mph tests seem more reasonable without riding at some dangerous speed (unless you run more than 20mph there is at least some risk of sliding out)
Also for a how long does board sustain mph would be effected by the wind and other factors as the test here is showing so you want to do it like rc pilots etc. Half the test with wind to your back half the test and inclination 0 or one way then second half of test other direction then second half opposite direction and average things to negate the wind and other environmental factors that should 0 out mostly when changing direction.
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For gentle riding at 15mph, I agree with this. If you ride at a higher average speed, this number is not very accurate however. This test and some others that I have not written up yet suggest that aerodynamic losses are far greater than electrical and mechanical losses combined at the speeds we ride at. Although there are some component choices which consume vastly more power (foamies, certain AT wheels) than a standard street build.
I have actually tested that, but I haven’t written it up yet. At 25mph, a racing tuck is 36% more efficient than standing straight up.
Not only is air drag the exponential of speed, its also the single largest cause of energy consumption by a huge margin. Air drag is really a function of you and speed, not the board at all. So if you know how much energy your riding style consumes in Wh/Mi you can extrapolate to any similar board. In addition, my consumption numbers during these conditions will not match your consumption numbers as my frontal area is different than yours.
The extrapolated range numbers serve to emphasize the point. It’s not easy for people to wrap their heads around Wh/Mi if they don’t have prior experience with this sort of testing. My target for this article is people new to esk8 through to experts. It should be pretty obvious that my quarter mile parking lot is not 72 miles long and that I can’t afford to spend fourteen hours riding to achieve this particular result in practice. But lets be real, the 72 mile figure isn’t the important one, the 5.5 mile figure is. In a stiff headwind, you can loose half your range easily. If you didn’t know that in advance, you could easily run out of charge in an inconvenient place while riding in those conditions.
I have tried this previously, and I found that it reduces the magnitude of environmental effects, but I still got 1 - 2 Wh/Mi variations between tests on different days. When you are looking for changes with a very small performance impact, this variability will render any data collected largely useless. The only solution I have come up with is to conduct tests on calm days or days with steady wind, conduct all tests in the same direction, and assume a 10% measurement variability between days. Testing inside a large warehouse would largely eliminate this issue but I don’t have access to one.
One other thing that I am considering doing is using an anemometer to measure the wind speed and ride in the same direction as the wind at the same speed to largely remove aerodynamic losses to find the real magnitude of electrical and mechanical losses. Unfortunately, gathering enough data points to really measure that at different speeds will probably take multiple months.
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To the range discussion:
For me personally it’s legit to state 10Wh/km for average consumption for range. From an engineers perspective eboards are (almost) all the same regarding efficiency. They all use the same cemistry of batterys, same motor architecture, have similar weight (sure some boards can be double as heavy but in a very small area) and use similar wheels. It’s a very different story for AT wheels, sure! It is not like in cars where you have a 3 ton pickup with 7 liter v8 and a small city car with 1.2 liter turbocharged engine. Differences in architecture (hub, belt, gear) have different pros and cons (less friction but worse heat dissipation for hubs). All in all the equal out themselves in normal testing conditions. At least from my experience. When I’m going for a long ride I’m not bombing all the time. Also I don’t have hills in my area. 10Wh/km is something bioboards, all chinese brands and so on use for their range estimation. So the guys stating here 12Wh/km which is completely fine imho. Look at the reviews of daniel kwan or press reset, when I have that right in mind you can estimate the range by using the Wh of the battery quite accurate (±5% seems ok).
Different story with AT wheels, personally i would half the range for an AT board (20-25Wh/km).
For the speed:
Without GPS it is nothing worth. You could also have lifted up the board, go full throttle and the remote would show 54km/h.
For all the rest stated about facts, claims, talking bs and so on:
You re goddamn right peoples 
But for the range discussion I disagree with you.
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I completely disagree with this statement… If i drew less current with more packs in parallel, i have less losses from ohmic heating… if I used thinner wires which results in higher resistances, again, more losses…
Different drive systems and speed controllers also plays a big role in the resultant efficiency…
Since you mentioned wheels, i assume you’re not just talking about power efficiency of the drive system, but overall workdone (in energy) by the vehicle given the amount of energy (batt power) put into the system.
If that’s the case, riding style, speed, rider’s weight, terrain, weather, wind speed, air density and rider’s surface area all play a part in determining the system’s efficiency.
So, no. All boards have VASTLY different efficiencies.
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Riding style & terrain are king though, doesn’t matter how much you crunch numbers. Riding style really matters. There is no such thing as an average consumption for range that is anything better than guestimation.
I’m averaging 40-45Wh/mile, which is considered decently high. I’ve seen others get 25-28Wh/Mile on similar boards. That’s a pretty huge spread.
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Barring size/heat they’re mechanically identical to hub motors. Curious why you would think they wouldn’t be applicable for comparison?
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We‘re talking about range testing and comparing. So yes you re right, when i draw a lot of current from a hub it will be less efficent than a belt drive motor.
But what I had in my mind: several boards, riders with the same weight start together for a ride. Same riding style, same route and Normal cruising. The differences in range won‘t be fundamental.
If you go to the extremes the slight differences in efficeny multiply and get more displayed.
I think riding style makes huge difference for range, never said anything against it. But for range test you have to assume an average rider. Therefore my experience is that 10-12Wh/km seems pretty accurate for PU wheels on flat area. Just my experience. If I ride hard in a hilly area it s a different story.
With losses comes heat, with heat comes more losses, heat inside a bed of urethane = more heat, its almost an exponential formula.
Comparing a closed solution to one spinning in free air…yea its different.
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Sure, but I’d say that still makes them an applicable comparison point as they are still the most mechanically similar. You can generally account for losses due to heat/resistance much easier than physical drag introduced via belt/gear/chain.
So we might be splittin hairs, but I’d call them a totally valid comparison.
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Put it this way: you do not have an overall efficiency. You have spots where you can tell under which load the system has which efficiency. The load includes all factors (rolling resistance, wind resistance, uphill; which is all influenced by speed, acceleration and weight). At high loads efficiency matters. Hub motors with small battery would be worse because of the heat which generates more resistance and so on like @linsus said.
But for the average efficiency spot at a moderate load the values are not differing that much from my experience.
When you compare loads it is all near together. The higher the load the more the gap widens.
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Since we’re talking about hubs and especially “the most powerful” hubs out there, I can’t help but think of the Raptor 2 and wonder how many riders have hit 10Wh/km at any speed, under any riding conditions, besides full downhill runs. I think it’s probably between zero and none, and it’s probably a tall order to find anyone who’s even done 20Wh/km on those hubs under any kind of “average” riding conditions. Sure, those hubs have issues, but the point is that assuming efficiency numbers that low for any kind of “average” rider under “average” riding circumstances is not realistic, especially for hubs.
@hummieee and devin published real world testing figures on the other forum doing laps on a flat circuit. they did test runs hoping to maximize mechanical output, and test runs hoping to maximize electrical effeciency. i’ll try to dig it up all the juicy data is hidden behind the “post flagged inappropriate”, the thread didn’t end well with devin pissing off everyone including jason but the data is still valid
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This topic of your most powerful hub motors seems to be infecting the whole forum right now.
This is a thread to discuss actual data so can we keep it on topic please.
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What annoys me is the clam of most powerful board then use a efficiency of 5mph
That is not normal use and there for a useless number that is there to deceive people
My v10 car shuts down 7 Cylinders for eco use so you can go 200mph for 20 miles or 200miles at 20mph (disclaimer made up car)
So under some crap I read I can do 200mph for 200miles on 3 gallons of fule. woot I’m so good and ultamat.
There’s a thread about average speed
12mph is normal in city’s
15-20mph is normal down roads
I’d suggest a range on 12mph, 20mph, max speed,
You also need to decide how badly you going to abuse the battery’s running them down to 2.5v a cell as per manufacture spec should you also consider that manufactures take 80% of copasity of battry is time to replace so -10% of a new pack should be applied to get a average
I charge my battery’s at 2.8-3v so i struggle to get 20 miles out of a 10s4p 444w pack (22.5w/m) I get 10-20wh/m averages 10 been super good roads and slow 20 been abusing it up and down hills
This is how 1 user that takes averages drives to the potential of a board and looks after a pack can quote range of 60 miles Some one fiddling the numbered can quote 120 miles calling it real world average
I think you missed the point of what Mars is saying. Electrical efficiency is a small part of overall system efficiency. The whole point of this thread is to practically test different aspects of overall system efficiency. If ohmic heating for an ideal board is 4w of power and an imperfect board uses 16w of power at 40A that’s completely irrelevant when aerodynamic losses are 1,100W.
According to this test, the combined electrical and mechanical losses for my board at 15mph is only 7 Wh/Mi. Aero losses at that speed are usually 8Wh/Mi in calm conditions. Considering that aero losses are largely dependent on the rider and speed, not the board, less than half of your power consumption is in the board itself.
That’s great, but let me ask a stupid question: If I took a slightly different board than mine with belts instead of gears, and rode the same way in the same conditions over the same terrain, am I likely to have a significant difference in power consumption? I don’t think so.
The whole point of this thread is to attempt to measure different aspects of boards, riding conditions, etc to see how they affect power consumption. Considering that you are using 40-45Wh/Mi, I’m going to assume that you either average over 30mph or you live in an incredibly hilly area. I don’t have access to real hills, so maybe you can conduct a similar test where you either climb different hill grades and measure power consumption or you climb a hill a different speeds.
To be perfectly honest, I don’t think that weight contributes significantly to overall power consumption. What does contribute to differences in power consumption is changes in rider frontal area. Weight loosely correlates to frontal area, as tall people are heavier than short people and fat people are heavier than skinny people. I have not tested it yet, but I would be willing to bet that a 100lb rider wearing a 100lb weight vest uses measurably less power than a 200lb rider.
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Agree with most of what you said here. Only part I would pick at is the weight thing. We are on low friction setups (nice bearings etc) so that is going to make the weight not a huge factor from an extra friction perspective but heavier person will have more inertia so if at rest take more force to accelerate then good ol’ F=ma you double the mass then you need double the force to get the same acceleration (negating extra effect of weight on frictional force).
Also more inclined you’re going up it seems more extra weight could be a factor. I say this because I’m light and on flat land around Chicago so I tend to get good efficiency (agree some of this has to do with being short so have a small surface area typically).
Some of my data too sorry mixed urethane and pneumatics but can see some idea:
Also my pneumatics are kinda low on air so there’s that.
Hehe edit wrong image
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I also agree with all of that besides the weight. As @wafflejock says, especially during acceleration the weight does all the difference. Generally speaking, my experiences with that is double the weiht, half the range.
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