smarty Posted November 5, 2018 Share Posted November 5, 2018 Hi Does anyone have or know of an app that will report current Wh/km or Wh/mile for their wheel? This would be great for when I'm on a longer ride and want to maximise my range. I know Wh/km is (mostly) a function of speed, but I don't want to creep home when I could be riding faster. A modest speed for a longer distance is much more efficient and fun (IMHO) than smashing it for the first 1/2 of the ride, then crawling back or worse - walking home! Link to comment Share on other sites More sharing options...
meepmeepmayer Posted November 5, 2018 Share Posted November 5, 2018 @palachzzz Maybe this would be a nice addition to Wheellog (if you haven't done so already). Link to comment Share on other sites More sharing options...
Chriull Posted November 5, 2018 Share Posted November 5, 2018 47 minutes ago, smarty said: Does anyone have or know of an app that will report current Wh/km or Wh/mile for their wheel? Afair the inmotion app reports Wh/km? And it's the only wheel that reports the battery current (to make this possible) by now? Not even thinking at the off factor of the gotways... But then still there are no (real) numbers till now now for efficiency of regenerative breaking... But this could be adopted empirically? Link to comment Share on other sites More sharing options...
palachzzz Posted November 6, 2018 Share Posted November 6, 2018 8 hours ago, meepmeepmayer said: Maybe this would be a nice addition to Wheellog (if you haven't done so already). Actually it's impossible task if we are talking about real Wh/km, and usual Bluetooth communication. For example, if you have 1000Wh battery - it doesn't mean that you can use full capacity. But prediction of the remaining mileage is a solvable problem 8 hours ago, Chriull said: Afair the inmotion app reports Wh/km? there the numbers are irrelevant to reality Link to comment Share on other sites More sharing options...
Seba Posted November 6, 2018 Share Posted November 6, 2018 51 minutes ago, palachzzz said: Actually it's impossible task if we are talking about real Wh/km, and usual Bluetooth communication. For example, if you have 1000Wh battery - it doesn't mean that you can use full capacity. What do you think about coulomb counting technique? At least with wheels that reports current flow direction (positive currrent for discharging and negative when braking) it would be possible to calculate energy that flows out or into battery. I know this will be inaccurate, but even if accuracy will be below 20% it would be worth to implement just as a measure of actual wheel efficiency? Link to comment Share on other sites More sharing options...
meepmeepmayer Posted November 6, 2018 Share Posted November 6, 2018 57 minutes ago, palachzzz said: Actually it's impossible task if we are talking about real Wh/km, and usual Bluetooth communication. You have current and voltage (so power), if you measure it for a certain time that's Wh, and if you look at the distance the wheel went in that time, can't you get a rough Wh/km number? Maybe average over 1 or 2 or 5 or even 10 seconds to get a sufficiently smooth number. Or do wheels (Gotways lol) report such false numbers that the result would be meaningless? The point would not be so much to estimate range, but to get a Wh/km measurement that is close to the physical reality of what the wheel actually uses. And then you could use that for ~75% of battery capacity to estimate the range, or so. But that's not important, just to get a Wh/km number in the first place. Also, what does it have to do with Bluetooth? I'm always interested in such technical details Link to comment Share on other sites More sharing options...
palachzzz Posted November 6, 2018 Share Posted November 6, 2018 25 minutes ago, meepmeepmayer said: You have current and voltage (so power) On which wheel?) Gotway and old KS transmits not battery but motor phase currents (moreover old KS transmitts negative currents if you ride back ) and true battery voltage, Inmotion transmitts compensated voltage and true battery currents, Ninebot Z stops update voltage if current more then several amps but true current, so in every such case it isn't real power, it's some numbers, not more. I know only one wheel with true voltage and true current - KS-18L. 25 minutes ago, meepmeepmayer said: Maybe average over 1 or 2 or 5 or even 10 seconds to get a sufficiently smooth number It doesn't work, currents may significantely change several times per split second, bluetooth updates to slow, and we can't catch real consumption if we're trying to integrate it to consumed Wh. We need at least several hundred samples per second to calculate real consumption, otherwise it is just one more number which may be mistaken for 50 percent or more depending on the aggressivity of riding. It may work with electric scooters and electric cycles, because they have more constant currents then EUCs. Link to comment Share on other sites More sharing options...
smarty Posted November 7, 2018 Author Share Posted November 7, 2018 After posting I did discover that the Inmotion App does report this. But the app is such a massive battery hog that I don't want to use it for more than a few minutes. Maybe I'll try at the beginning of my next ride and see what data I get. Just hope my phone doesn't catch fire from the massive power drain from the Inmotion app! Yeah, I can now see it is problematic given the different data transmitted by each wheel. Link to comment Share on other sites More sharing options...
smarty Posted November 23, 2018 Author Share Posted November 23, 2018 I've been using my Charge Doctor to measure my avg Wh/km. I seem to be averaging about 16 Wh/km - which will only give me 30km range on my 480 Wh V8. Although at 40% battery the wheel does slow down, so the power consumption will drop. As a matter of interest, I have a power meter on my push bike (carbon racing). At 30km/h I'm using about 200W. Calculate this out and it translates to 6.7 Wh/km Link to comment Share on other sites More sharing options...
Mono Posted November 23, 2018 Share Posted November 23, 2018 On 11/23/2018 at 1:04 AM, smarty said: I've been using my Charge Doctor to measure my avg Wh/km. I seem to be averaging about 16 Wh/km - which will only give me 30km range on my 480 Wh V8. Although at 40% battery the wheel does slow down, so the power consumption will drop. As a matter of interest, I have a power meter on my push bike (carbon racing). At 30km/h I'm using about 200W. Calculate this out and it translates to 6.7 Wh/km On the EUC you probably have a considerably larger front surface and a worse drag coefficient. Using the CD you also measure (parts of the) charge and conversion losses that I assume you disregard with the power meter. Link to comment Share on other sites More sharing options...
palachzzz Posted November 23, 2018 Share Posted November 23, 2018 200w it's unbelievable for 30km/h, because only air loss at this speed is more than 300w, plus mechanical loss, minus efficiency, it should be more than 500w. Usually I saw about 600-800w on V8 at about 30 km\h speed. Tipical air losses for electric bike: Link to comment Share on other sites More sharing options...
smarty Posted February 14, 2019 Author Share Posted February 14, 2019 I can maintain 30kmh easily when cycling, which is 200W for me, well below my 250w threshold. The powermeter is attached to my bike crank. 500w is impossible for all but the top professional riders to maintain for more than a few minutes. However you might be referring to electrical watts into your electric bike motor - which will be much higher due to mechanical inefficiencies and motor losses. Yes - it is a bit disingenuious to compare bike vs uniwheel efficiencies because of the losses that @Mono described. Link to comment Share on other sites More sharing options...
MaiKi Posted February 14, 2019 Share Posted February 14, 2019 @smarty the 200 watt is only your own power and you dont have any electric motor on your bike? (in front or back wheel?) The air losses diagram is shoqing the required motor power against the wind? In this case you cant compare it with a normal bike 🤔⁉️ And to get a avarage wh/km the option to add the battery wh could be helpful after a few rides from full battery to low/empty battery. In this case, however, the function is just as inaccurate as if you only judge by average range?! Avarage wh/km = avarage range Link to comment Share on other sites More sharing options...
LanghamP Posted February 14, 2019 Share Posted February 14, 2019 On 11/23/2018 at 8:42 AM, palachzzz said: 200w it's unbelievable for 30km/h, because only air loss at this speed is more than 300w, plus mechanical loss, minus efficiency, it should be more than 500w. Usually I saw about 600-800w on V8 at about 30 km\h speed. Tipical air losses for electric bike: I can confirm that going around 30 kmh, give or take, does use around 200 watts, and probably much less, because I already know my speed and peak watts on a power meter. The modern road bike is mankind's greatest invention. Link to comment Share on other sites More sharing options...
Smoother Posted February 14, 2019 Share Posted February 14, 2019 On 11/6/2018 at 8:21 AM, Seba said: What do you think about coulomb counting technique? At least with wheels that reports current flow direction (positive currrent for discharging and negative when braking) it would be possible to calculate energy that flows out or into battery. I know this will be inaccurate, but even if accuracy will be below 20% it would be worth to implement just as a measure of actual wheel efficiency? This is very common on a good solar panel (PV) installation. A thing called a shunt is placed on one lead of the battery and it measures energy in and out, then reports to a monitor which tells you how much power has been stored, or used. It wouldn't be difficult to average every couple of seconds and send this packet data to the APP. Spikes exist when the wheel is active (roots, bumps. etc, but that's what averaging is for. It would never be "reporting to the scientific world" accurate, but it would be close enough. Link to comment Share on other sites More sharing options...
Marty Backe Posted February 14, 2019 Share Posted February 14, 2019 Interesting idea but not really needed after you mature in your riding. There becomes a point that you intuitively know your wheel and understand its range given the battery and current riding conditions (speed, temperature, wind, etc). After years of riding various wheels I understand that they all get basically the same gas mileage. So I know if I'm jumping on a 1000wh wheel I can expect to get X-miles under Y-conditions. I have never run out of battery even when doing an extremely long ride. All I need is my battery percentage and I can usually predict my energy consumption fairly accurately. Hopefully what I'm saying is universal (my experience is not rare). Link to comment Share on other sites More sharing options...
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