Chriull Posted December 3, 2016 Share Posted December 3, 2016 Since i did not find the original thread ( imho the posts were just "hidden" in some other thread..?) from the first dynamometer results published at http://electrotransport.ru/ (linked here by @Raptor) here a new thread with some new results: http://electrotransport.ru/ussr/index.php?msg=973382 The full tests including description of the measurements are published at http://airwheel.ru/test-monokoles-na-dinostende/ (also with a comment that the dynamometer is made for motorcycles with much more HP and so the results are not really exact absolute numbers but a nice comparison between the different wheels)! Also i did not see a comment about the "measurement probs" he mentioned in his first test: He could not start the dynamometer with full power from the wheels, because some fuses burnt... So he had to accelerate it "slowly" up to ~10-15km/h before he could apply full thrust. So some/most of the charts show some quite low powers for low speeds. Mabye he found a way to overcome this prob or it is still seen (imho in the charts for the high power 18 inch wheels?) Some interesting first points: - the IPS Zero shows some strange behaviour: The power output halves for speeds about 16 km/h! Also with a max power of 1.1kW it is one of the weakest of the tested models... - bigger batteries (capacity) give more power! ( how to translate "Na no na ned" to english? ) - nicely to be seen in the comparison between the KS16 340Wh and 840Wh model. - The MSuper V3 1600Wh 84V started a new era: it shows a max power of 4.7kW! - a nice statement regarding Airwheel (not included in the summary charts): "Test shatters all hope that this device can drive" -Test of ACM with custom LiFePo4 batteries: ~30% power increase! - Test of Inmotion V8 with Samsung INR18650-30Q 3000mAh cells: ~20% power increase, but the internal fuse was not able to withstand the increased current... It would be great to see the results from @EUC Extreme's custom Gotway in comparison to a standard factory version! A Quick overview of the results (links to the pics of his homepage): 14 inch wheels: 14 inch with more "power": 16 inch wheels: 18 inch wheels: Link to comment Share on other sites More sharing options...
Spiken Posted December 3, 2016 Share Posted December 3, 2016 Very interesting, thanks ! Link to comment Share on other sites More sharing options...
Chris Westland Posted December 3, 2016 Share Posted December 3, 2016 10 hours ago, Chriull said: - the IPS Zero shows some strange behaviour: The power output halves for speeds about 16 km/h! Also with a max power of 1.1kW it is one of the weakest of the tested models... - bigger batteries (capacity) give more power! ( how to translate "Na no na ned" to english? ) - nicely to be seen in the comparison between the KS16 340Wh and 840Wh model. - a nice statement regarding Airwheel (not included in the summary charts): "Test shatters all hope that this device can drive" 14 inch wheels: Thank you @Chriull for posting and translating this. I have owned both an Airwheel X3 and currently an IPS Zero, and a lot of the feedback on this forum for the IPS Zero has been disparaging concerning power output and predictability (notably recommending KS, Gotway and Inmotion as better choices). I love the Zero for its lightness (10kg) and its singular and dramatic improvement over the Airwheel (which was basically an annoying EUC). This definitely suggests that there are problems with the IPS Zero at its higher speeds, and in particular that it should not be driven over 20km/h (where it is locked when they send it to you). Link to comment Share on other sites More sharing options...
Chris Westland Posted December 3, 2016 Share Posted December 3, 2016 "Crossout, forget and never even look in the direction of Airwheel"... agree, an this is even an X8, not an X3 like I had! Link to comment Share on other sites More sharing options...
Chriull Posted December 3, 2016 Author Share Posted December 3, 2016 39 minutes ago, Chris Westland said: Thank you @Chriull for posting and translating this. Merits for the link belong to @Raptor showing us this. Translating was done by google - i could not understand a single letter in russian ? Also the google translation is almost not understandable... 39 minutes ago, Chris Westland said: ...and in particular that it should not be driven over 25km/h. Be carefull with the speed on the x-axis! It does not really have a or just a bit of a meaning - the measurements is only (mainly) to determine the max power output! with the dynamometer almost all/all wheels get overpowered at higher speeds! Link to comment Share on other sites More sharing options...
Chris Westland Posted December 3, 2016 Share Posted December 3, 2016 8 hours ago, Chriull said: Merits for the link belong to @Raptor showing us this. Translating was done by google - i could not understand a single letter in russian ? Also the google translation is almost not understandable... Be carefull with the speed on the x-axis! It does not really have a or just a bit of a meaning - the measurements is only (mainly) to determine the max power output! with the dynamometer almost all/all wheels get overpowered at higher speeds! Then a thanks to @Raptor as well for the posts and a thanks to @Chriull and @Raptor as well for the posts and translations. I am used to reading motorcycle dynamometer output (in cycle mags; I haven't actually used one) and the real meaning of a horsepower drop. The output power of the motor is the product of the torque that the motor generates and the angular velocity of its output shaft (which is represented as "speed" on the x-axis). What that represents is a sudden torque drop at ~16km/h in the forward direction (which I assume is due to the power supplied dropping dramatically at this level of draw). In practice, inertia would keep you going and you might not notice this on acceleration; and the motor breaking (or regeneration) would still work at those speeds, so you would not notice a comparable drop in decelerating. But the balancing of the IPS above ~16km/h would be "wonky" because you would not have enough forward torque to quickly stabilize a pitch forward, and there would be an abrupt change in the regenerative braking force to the forward force. This may account for some of the "Face-plant" reports we have heard about. The power drop at ~16km/h is an abrupt 1.1HP --> .45HP in a very short velocity change of 1km/h between 16-17km/h... pretty significant. For the torque drop @ ~16km/h I compute 230rpm (for a 14"diameter/44"circumference wheel) which means an abrupt reduction of forward torque from 25 ft-lbs to 10 ft-lbs after you hit ~16km/h. Discuss!? Link to comment Share on other sites More sharing options...
FreeRide Posted December 3, 2016 Share Posted December 3, 2016 The plot seems to say that you don't get any extra horsepower on the mSuper V3+ 1600 until you exceed 23 km/h. That does not sound right. Am I reading something wrong? Link to comment Share on other sites More sharing options...
nomad Posted December 3, 2016 Share Posted December 3, 2016 So award for best bottom end performance goes to ACM and V5F ? Also the V5F+ batteries have 30% more power than the nonplus tested here! No wonder the Msuper v3 felt weaker in accel and steep climb/slope for me. At 23 km/h the tiltback kicks in on V5F you can see a dip on the chart. V3+ looks like the ultimate high speed cruiser... Link to comment Share on other sites More sharing options...
trya Posted December 3, 2016 Share Posted December 3, 2016 12 hours ago, Chriull said: how to translate "Na no na ned" to english? @Chriull where did you get this? Couldn't find anything similar in the original text. I can help with translation if some parts are unclear Link to comment Share on other sites More sharing options...
Chriull Posted December 4, 2016 Author Share Posted December 4, 2016 27 minutes ago, trya said: @Chriull where did you get this? Couldn't find anything similar in the original text. I can help with translation if some parts are unclear Understandable - this is a vienese slang expression, meaning something like "sure, what else".., more or less Link to comment Share on other sites More sharing options...
Mono Posted December 4, 2016 Share Posted December 4, 2016 Haven't there been speed tests of the Inmotion V8 going beyond 30km/h? That would contradict the above measurements which show a cut off at 24km/h. Seems like a relevant difference... Link to comment Share on other sites More sharing options...
FreeRide Posted December 4, 2016 Share Posted December 4, 2016 Seems like the cut off may have been related to the load being placed on the wheel by the dyno. Link to comment Share on other sites More sharing options...
Chris Westland Posted December 4, 2016 Share Posted December 4, 2016 22 hours ago, Chris Westland said: 13 hours ago, MoNo said: Haven't there been speed tests of the Inmotion V8 going beyond 30km/h? That would contradict the above measurements which show a cut off at 24km/h. Seems like a relevant difference... I'm guessing that since this was a motorcycle dynamometer, that it was putting a lot of resistance on the wheel and locking up the wheel beyond a certain point, whereas in real use, the inertia of the wheel and a little bit of torque at hi RPM might still be available, so 30km/h would be achievable, even though the dynamometer overloads this stationary wheel at a lower speed. These motorcycle dynamometers are designed for a 500kg/150HP machine, and they are using it on a 10-15kg/1HP EUC. Typically these would be inertia' type dynamometers providing a fixed inertial mass load (suitable for ~150HP machines) calculating the power required to accelerate that fixed and known mass that's much too big for EUCs. Air-cooled eddy current dynamometers are currently the most common absorbers and use a conductive iron disc moving across a magnetic field to produce resistance to movement, and this feeds into the computer to plot the RPM/HP graphs. Their machine is probably too big for EUCs, but the graphs are instructive anyway. Link to comment Share on other sites More sharing options...
Chriull Posted December 4, 2016 Author Share Posted December 4, 2016 5 hours ago, FreeRide said: The plot seems to say that you don't get any extra horsepower on the mSuper V3+ 1600 until you exceed 23 km/h. That does not sound right. Am I reading something wrong? 3 hours ago, nomad said: So award for best bottom end performance goes to ACM and V5F ? At low speeds, as already stated the charts are to be looked at very cautiousely. At his first test he blew the fuses of the KS so he started to accelerate slowly to about 10-15 km/h to let the wheel survive. I have no idea if this is still true for rhe second tests he performed. But as it looks especially for the v3+ 1600 he did a very "slow" start - imho.if the low speed power/torque values have any meaning can only be verified by asking in the russian forum - maybe @Cloudwants to do this? As hard it is to read the russion to german google tranlation imho there is no chance to get a sophisticated answer from an google translated german to russian question. Quote Also the V5F+ batteries have 30% more power than the nonplus tested here! There is no test of an v5f+? You mean that the v5f+ has 30% more capacity? The power increase by higher battery capacity comes from more cells in parallel! (And in some cases like in the bonus section from the more powerfull cells) 40 minutes ago, MoNo said: Haven't there been speed tests of the Inmotion V8 going beyond 30km/h? That would contradict the above measurements which show a cut off at 24km/h. Seems like a relevant difference... By the high load from the dynamometer most wheels shut off before reaching max speed. If you look in the bonus part of the linked site you see the v8 with better batteries reaching higher speeds, but also burned fuses after the second test.. with most of the charts one see a nice declining slope after the max power peak. This is imho the proportional decreasing torque with higher speeds intrinsic to bldc motors. With the high loads of the dynamometer this could lead/leads easily anytime to an "overlean" resulting in an "cut-off" similar situation. Like in many faceplant reports here far below max speed of the euc's... the forward pitch (acceleration) in this tests is done by hand. The difficult part at low speeds is, like mentioned above to accelerate not too much to not overpower the mainboard and inflict a premature shut off or burned fuse. Also at higher speeds after the max power output one imho also has to choose acceleration not too much to not inflict an "overlean" which is a quite difficult "borderline walk". so this charts are mainly to reveal the max power - if he managed to get a nice pitch(acceleration) of the wheel this also results in a nice speed over max power(torque) at this speed chart. If not and there are lower powers before and after the absolute max power this _does not_ proove any shortcoming (powerwise) of the wheel! So quite some sensible interpretations are needed for every test run! ps.: its about 2 o clock in the morning over here and i had a very "happy" evening before - so i did my best and hope that everything i tried to state is ok after some rereading - if not i'll reject this after some critical comments and/or after rereading this tomorrow ? Pps: @Cloudmaybe you have enough time and like to translate this to russian and ask ecodrift for a veridication of my statements? I'd be quite interessted in his answer! Link to comment Share on other sites More sharing options...
nomad Posted December 4, 2016 Share Posted December 4, 2016 8 hours ago, Chriull said: There is no test of an v5f+? You mean that the v5f+ has 30% more capacity? The power increase by higher battery capacity comes from more cells in parallel! (And in some cases like in the bonus section from the more powerfull cells) I mean the cells are 30% more powerful (capacity is 50% higher) Link to comment Share on other sites More sharing options...
Chris Westland Posted December 4, 2016 Share Posted December 4, 2016 12 hours ago, Chriull said: At low speeds, as already stated the charts are to be looked at very cautiousely. At his first test he blew the fuses of the KS so he started to accelerate slowly to about 10-15 km/h to let the wheel survive. I have no idea if this is still true for rhe second tests he performed. But as it looks especially for the v3+ 1600 he did a very "slow" start This would confirm my suspicions about the dynamometer being too big for a little EUC ... it might be comparable to standing a 500kg rider on the EUC and wondering why the fuses blow. Link to comment Share on other sites More sharing options...
Snurre Posted December 4, 2016 Share Posted December 4, 2016 Thanks @Chriull for an interesting post. I believe the original thread you were referring to is here in the King Song section. I had a look at the test-rig video again and @Chris Westland, it seems they are actually simulating the rider weight albeit crudely. As a curiosity sideline: what is the explanation for the ripples in the measurements? They seem very similar across wheels except for the IPS Zero at 16kph so could that be a test-rig artifact? Link to comment Share on other sites More sharing options...
Chris Westland Posted December 4, 2016 Share Posted December 4, 2016 Here is the video ... I applaud them for what appears to be a very well thought out set-up, with the rider's weight simulated on the rig. But (correct me if I am mistaken) I think the problem arises because in reality your wheel torque is accelerating the mass of the wheel+rider (~85kg for me) whereas in the dynamometer tests the downward pressure in the rig just adds traction, but the torque is accelerating the equivalent of a ~500kg mass (the dynamometer absorber). I would contend that in practice most of these EUCs perform much better than it appears from the graphs in these tests. Certainly with my own IPS Zero I haven't noticed any torque drop at 16kmh ... and it's something I really do worry about! Link to comment Share on other sites More sharing options...
Donafello Posted December 4, 2016 Share Posted December 4, 2016 I'm wondering if the 1600wh has less torque on the low end then the 1640wh. But as you gain speed it seems the 1600wh really starts to take off. Link to comment Share on other sites More sharing options...
Mono Posted December 4, 2016 Share Posted December 4, 2016 17 hours ago, Chriull said: By the high load from the dynamometer most wheels shut off before reaching max speed. Isn't the "load from the dynamometer" exactly what we see as measurement on the y-axis of the graphs? Link to comment Share on other sites More sharing options...
Chriull Posted December 4, 2016 Author Share Posted December 4, 2016 24 minutes ago, MoNo said: Isn't the "load from the dynamometer" exactly what we see as measurement on the y-axis of the graphs? No - the dynamometer it is a rotating mass. The power shown on the y axis is the power provided by the wheel to accelerate this mass to higher speeds. edit: so yes, it is exactly the load from the dyno one sees on the y-axis... Link to comment Share on other sites More sharing options...
Chris Westland Posted December 4, 2016 Share Posted December 4, 2016 17 hours ago, Chriull said: with most of the charts one see a nice declining slope after the max power peak. This is imho the proportional decreasing torque with higher speeds intrinsic to bldc motors. With the high loads of the dynamometer this could lead/leads easily anytime to an "overlean" resulting in an "cut-off" similar situation. Like in many faceplant reports here far below max speed of the euc's... I think there is a steady buildup of friction in electric motors, which is why they tend to lose power and ultimately stall as they go faster (they can't stay ahead of the rotating currents, and so their timing slowly goes off). I'm guessing a heavy inertial load, such as you have on the dynamometer, tends to additionally force the motor's magnets out of proper timing and results in the premature stalling -- the high-end drop-off on these graphs (at least compared to the high-end stats that we see elsewhere on this site and on manufacturers sites). So I suspect that in reality the wheels all do better than is depicted here ... higher top speeds, less stalling at low speeds. But these dynamometer charts highlight competitive differences and potential faults in each EUC. Link to comment Share on other sites More sharing options...
Slaughthammer Posted December 5, 2016 Share Posted December 5, 2016 4 hours ago, Chris Westland said: I think there is a steady buildup of friction in electric motors, which is why they tend to lose power and ultimately stall as they go faster (they can't stay ahead of the rotating currents, and so their timing slowly goes off). No, this is actually not at all the case. The problem at higher rpms is, that the voltage induction caused by the magnets moving past the coils reduces the actual effective voltage applied to the motor, thus limiting the maximum current and the torque. After watching the video, I would guess that the cutoffs are induced by draining the battery unter cutoff voltage of the BMS. Seems that the batteries are not fit to provide 20+ amps for a longer time, thus voltage drops rather quickly and hence the shutoff. The only figure i would give some credibillity resulting these rather crude testing environment is the absolute maximum power. Not the speed at which it is produced, and surely not how fast the wheel can safely go. Link to comment Share on other sites More sharing options...
Chris Westland Posted December 5, 2016 Share Posted December 5, 2016 26 minutes ago, Slaughthammer said: No, this is actually not at all the case. The problem at higher rpms is, that the voltage induction caused by the magnets moving past the coils reduces the actual effective voltage applied to the motor, thus limiting the maximum current and the torque. OK, that makes sense. The power factor is going to vary because of stator and rotor leakage and magnetizing reactances. But I thought your boards were supposed to apply power factor correction to control this. Maybe there are limitations. But I would generally think that friction would be a significant factor as speed rises (both in the axle and where rubber meets road). Link to comment Share on other sites More sharing options...
Slaughthammer Posted December 5, 2016 Share Posted December 5, 2016 27 minutes ago, Chris Westland said: But I would generally think that friction would be a significant factor as speed rises (both in the axle and where rubber meets road). Well, at low speeds, rolling resistance is a factor, but small compared to the available torque, so no problem. At higher speeds, the air resistance dominates over rolling resistance, growing proporioinal to v³, whereas rolling resistance grows linear with the speed. As for the axle, if the bearings used deserve beeing called bearings, friction losses should be negligible. What might actually come into account is that the resistance of the coils rise with temperature, thus further limiting maximum current and torque. Espeacially in this test situation, with maximum power applied for longer periods this might be an additional issue. But the main speed limiting factor is the voltage drop due to counterinduction. This has nothing to do with magenetising reactance or leaking, it's just the motor acting as a generator when spinning. Link to comment Share on other sites More sharing options...
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