dmethvin Posted January 29, 2018 Share Posted January 29, 2018 56 minutes ago, Scatcat said: The low voltage triggers my scepticism. ... I might be wrong, no two ways about it. It just seems like it is a voltage chosen because of stoopid standards, rather than from considering what is actually the best way to go about it. It sure does seem strange, and I'd also think that it might be driven by some emerging standard like UL 2272 which up to now has mainly applied to hoverboards. At those lower voltages they're going to need really thick wires (even for the charger) which causes its own set of problems that have to be mitigated. I sure hope they explain more about the reasoning behind the engineering choices. 1 1 Quote Link to comment Share on other sites More sharing options...
US69 Posted January 29, 2018 Share Posted January 29, 2018 1 hour ago, Scatcat said: The low voltage triggers my scepticism. Unless the wiring and all the circuits are truly scaled to handle such amperage; and unless they've found a way to flatten out the torque curve to give some margin in the top-end - the move DOWNwards rather than UPwards in voltage seems counterintuitive for creating a dependable EUC with high longevity. I might be wrong, no two ways about it. It just seems like it is a voltage chosen because of stoopid standards, rather than from considering what is actually the best way to go about it. i guess we just have to read between the lines Jason has provided! While he found good words for the "Overall Quality" of the Z10, he also says that: - it does not Play in the same (power)league than the top 84 V models from the competition... - It has (only) achieved a maximium of 1500Watt on a Dynamo test (while Top GW/KS go up to over 3000, even 4000 Watts on those test rigs) - the lower voltage will bring stress to wires and batterys There are plenty of reasons why EUCs and E-bike go higher and higher in voltage with their Serial batterys, to move back to a 14Seriell System, which only has been seen on the first Solowheel is a pretty bad idea. But thats just my 2 Cents.... 1 Quote Link to comment Share on other sites More sharing options...
Electroman Posted January 29, 2018 Share Posted January 29, 2018 (edited) Thanks for posting Jason, appreciate it and made my day. Will not even begin to try to read anything more out of this atm so suppose I have to sit back and just wait for reviews, release later, heck I do not even know if it will be available to me yet living in EU and on a budget, maybe I give up my plans on the Oled TV in a near future and go all in should I feel it will be worth it down the road, then again maybe not? So much speculation, extrapolate out of what is already known up til now without further technical info available may be futile, at least for me but what I really want is to try one and see how it feels should first initial reviews be great? At the prices mentioned here (maybe not in EU ) perhaps it could be a great wheel but should Ninebot give us all everything we want I have this feeling the cost would go up and that by some margin, but what do I know I admit it's all speculations. Me too want the mega batt packs/high voltage/freak power level, lift handle/button and perhaps more than anything else redundancy, and all the other things to make us all super happy.. Edited January 29, 2018 by Electroman 2 Quote Link to comment Share on other sites More sharing options...
Cranium Posted January 29, 2018 Share Posted January 29, 2018 (edited) 6 hours ago, Mono said: 52V vs 72V requires 18% (=sqrt(72/52) - 1) wider wires, everything else being equal. 52V is plenty to operate a highly durable 10kW electric motor, ie for motor power specifications far beyond what EUCs would actually need. Where does your equation come from? I am unfamiliar with a thumb-rule using voltage to determine wire size. Power = Voltage * Current (P=V*I). I = P/V. For a given power level of say 1000W, then with the known voltages I can work out that at 52V it draws 19.2A and at 72V it draws 13.9A for a difference of 27.8% in current. The increased wire size may be trivial to handle the difference in current but the increased trace size on the board is another matter. Using a trace width calculator, the width of your power traces have to increase by 36% for the increase in current. This makes it more difficult to place components on the board with the wider traces. Maybe this was another reason that they went with the 2 board design. Edited January 29, 2018 by Cranium 2 Quote Link to comment Share on other sites More sharing options...
Mono Posted January 29, 2018 Share Posted January 29, 2018 2 hours ago, Cranium said: Where does your equation come from? Out of my head. The surface area (which determines the max current, IIRC) grows with the square of the diameter. Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 29, 2018 Share Posted January 29, 2018 (edited) 1 hour ago, Mono said: 10 hours ago, Mono said: 52V vs 72V requires 18% (=sqrt(72/52) - 1) wider wires, everything else being equal. 3 hours ago, Cranium said: ... Using a trace width calculator, the width of your power traces have to increase by 36% for the increase in current. ... I'd have a third number : The resistance is "invers proportional" to the surface (R=k/A). For the same power dissipation in the wire P=U1*I1=U2*I2=k/A1*I1*I1=k/A2*I2*I2. With the U1/U2 = 75/52 I1/I2=52/72. So A2/A1=(75/52)^2=2,1 Edit: ups - have thrown some senseless 75's in there... with 72 and 52 the factor gets 1.9 Edit2: also the higher surface area in "contact" with the cooler air of the thicker wire has to be considered, so the full factor of 1.9 should not be needed... Edited January 29, 2018 by Chriull 3 Quote Link to comment Share on other sites More sharing options...
exoplanet Posted January 30, 2018 Share Posted January 30, 2018 12 hours ago, Mono said: 52V vs 72V requires 18% (=sqrt(72/52) - 1) wider wires, everything else being equal. 52V is plenty to operate a highly durable 10kW electric motor, ie for motor power specifications far beyond what EUCs would actually need. depend on your speed, doest it? Quote Link to comment Share on other sites More sharing options...
Cranium Posted January 30, 2018 Share Posted January 30, 2018 4 hours ago, Mono said: Out of my head. The surface area (which determines the max current, IIRC) grows with the square of the diameter. I was thinking that was what you are doing. I think you need to multiply your result by 2. You determined the change in radius for pi*r^2. 3 hours ago, Chriull said: With the U1/U2 = 75/52 I1/I2=52/72. So A2/A1=(75/52)^2=2,1 Or we can just use Chriull's formula. It appears spot on! Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 30, 2018 Share Posted January 30, 2018 On 26.1.2018 at 10:57 PM, Jason McNeil said: In dyno testing they have achieved loads of 1500W of power output On 27.1.2018 at 8:16 AM, KingSong69 said: So the announced 1500W is a Max and not a nominal? 15 hours ago, KingSong69 said: - It has (only) achieved a maximium of 1500Watt on a Dynamo test (while Top GW/KS go up to over 3000, even 4000 Watts on those test rigs) 1500W max output power would be really low! Even the KS16B/C reached 2200W (advertised as 3000W max, 800W nominal) in @EcoDrift's dyno test. Looking at the specs in the first post here in the topic (sorry - did not look if they are still up to date) 1500W maximal peak output power would be "horrible" even for the weakest Z. (1200W nominal) I hope there was some miscomunication or typing errors in @Jason McNeil's notes?! ... And the 1500W were from a long time (continous) load/stress test with 40°C ambient temperature - which would be a great result.... Quote Link to comment Share on other sites More sharing options...
US69 Posted January 30, 2018 Share Posted January 30, 2018 16 minutes ago, Chriull said: Looking at the specs in the first post here in the topic (sorry - did not look if they are still up to date) My guess would be the announced numbers, 1200 to 1800Watt, are perhaps the Maximal Watts, and not the nominal.... Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 30, 2018 Share Posted January 30, 2018 (edited) 1 hour ago, KingSong69 said: My guess would be the announced numbers, 1200 to 1800Watt, are perhaps the Maximal Watts, and not the nominal.... Pffff... That would be quite low - imho like the E+/S2 til P range (unfortionately airwheel.ru seems to be down right now - can't look at their test results...) But if so that would be a definitiv reason to _not_ be interested in the Z series anymore. I liked their looks/design (especially the fat tire! ) and decided to try them this summer... ? I would have been even ready to forget all the firmware update desasters of the ninebot e+... But stepping back powerwise compared to my Ks16S, even below the KS16C is absolutely out of question... Would be also quite dangerous wheels going up to 40 km/h with just 1800W max peak power - somehow i can't (don't want) to believe this "interpretation" of the numbers... PS: ... Also i had the hope getting a wheel again without this high pitched whining sounds... @cranium was the Ninebot P silent or did it already have this high pitched sound like the KS/GW? @Jason McNeil what was your experience sound wise? Edited January 30, 2018 by Chriull Quote Link to comment Share on other sites More sharing options...
Scatcat Posted January 30, 2018 Share Posted January 30, 2018 20 hours ago, Mono said: 52V vs 72V requires 18% (=sqrt(72/52) - 1) wider wires, everything else being equal. 52V is plenty to operate a highly durable 10kW electric motor, ie for motor power specifications far beyond what EUCs would actually need. Yes, 52V is plenty. It just feels a bit counterintuitive, as higher voltages should put less stress on the wiring. OTOH if they actually beef the wires up to something that can handle higher currents without undue heat, then it should be perfectly OK. It's just that we've had so many problems with overheating wires, that upping the current seems a stoopid thing to do. Quote Link to comment Share on other sites More sharing options...
Scatcat Posted January 30, 2018 Share Posted January 30, 2018 2 hours ago, KingSong69 said: My guess would be the announced numbers, 1200 to 1800Watt, are perhaps the Maximal Watts, and not the nominal.... If that is the case, then my next wheel will NOT be a 9B1 Z10. Going from ~2kW continuous to 1.8kW max is a total no-go. Let's hope the 1500W was continuous power. Quote Link to comment Share on other sites More sharing options...
US69 Posted January 30, 2018 Share Posted January 30, 2018 1 hour ago, Chriull said: was the Ninebot P silent or did it already have this high pitched sound like the KS/GW? btw the GW Tesla doesnt have that Sound anymore...and afaik the 18L doesnt, also. 1 Quote Link to comment Share on other sites More sharing options...
Lukasz Posted January 30, 2018 Share Posted January 30, 2018 To cut all those worries - If Ninebot guys read this forum - please be so kind and post on YT long-uphill-mountain-climbing-at-speed video for Z10 as Kingsong *(even for small KS14) did Z10 shall be capable of at least the same slope with twice the speed. Show us please some evidence of design real life test. Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 30, 2018 Share Posted January 30, 2018 1 hour ago, Chriull said: Pffff... That would be quite low - imho like the E+/S2 til P range (unfortionately airwheel.ru seems to be down right now - can't look at their test results...) Just for the files (since i reached https://airwheel.ru/2017/10/27/test-monokoles-na-dinostende/ again): Ninebot S2 reached max peak power of 1400 W. ( It seems that Ninebot P was not tested?) So i can't really believe that the (max peak) power of the new Z did not noteable increase compared to the S2... Quote Link to comment Share on other sites More sharing options...
Scatcat Posted January 30, 2018 Share Posted January 30, 2018 45 minutes ago, Chriull said: Just for the files (since i reached https://airwheel.ru/2017/10/27/test-monokoles-na-dinostende/ again): Ninebot S2 reached max peak power of 1400 W. ( It seems that Ninebot P was not tested?) So i can't really believe that the (max peak) power of the new Z did not noteable increase compared to the S2... Yes, it seems inconceivable that the max power would be so low. Especially with the speeds, max loads and climbing stats stated. 1 Quote Link to comment Share on other sites More sharing options...
Scatcat Posted January 30, 2018 Share Posted January 30, 2018 (edited) Formulas aside: can't they just use 8 AWG wire, and the discussion is moot? Edited January 30, 2018 by Scatcat 2 Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 30, 2018 Share Posted January 30, 2018 (edited) 14 minutes ago, Mono said: Right, the resistance is inverse proportional to the surface, but that means the resistance is inverse proportional to the square of the diameter, not that the square of the resistance is proportional to the diameter. I just did the calculation with the surface Areas (A1 and A2) not with diameters. So the calculation for the increase in radius for the same power dissipation: With R=some_coefficient/A=some_other_coefficient/r^2 P=U1*I1=U2*I2=I1^2/r1^2=I2^2/r2^2 So r2/r1=I2/I1=72/52=1,44 Your calculation shows the increase in radius for the same voltage drop along the wires: U=R1*I1=R2*I2=I1/r1^2=I2/r2^2 r2/r1=sqrt(I2/I1)=sqrt(72/52)=1,18 Edited January 30, 2018 by Chriull 1 1 Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 30, 2018 Share Posted January 30, 2018 (edited) 26 minutes ago, Scatcat said: Formulas aside: can't they just use 8 AWG wire, and the discussion is moot? Or even better like shown in the video linked (*)from @Cranium connect the BLDC with _real_ wires (*) Edited January 30, 2018 by Chriull 2 Quote Link to comment Share on other sites More sharing options...
Mono Posted January 30, 2018 Share Posted January 30, 2018 (edited) 26 minutes ago, Chriull said: I just did the calculation with the surface Areas (A1 and A2) not with diameters. So the calculation for the increase in radius for the same power dissipation: With R=some_coefficient/A=some_other_coefficient/r^2 P=U1*I1=U2*I2=I1^2/r1^2=I2^2/r2^2 So r2/r1=I2/I1=72/52=1,44 72/52 is apparently 1.38, but that's just a minor correction. So how could we account for the increase in wire surface that dissipates the heat then? It would be the same factor, 1.38? That is, we end up with "1.38 cooler wires" if we increase the wire diameter by 1.38, while having the same power dissipation. So what's the diameter where we see the same wire temperature? Quote Your calculation shows the increase in radius for the same voltage drop along the wires: U=R1*I1=R2*I2=I1/r1^2=I2/r2^2 r2/r1=sqrt(I2/I1)=sqrt(72/52)=1,18 Agreed. Edited January 30, 2018 by Mono Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 30, 2018 Share Posted January 30, 2018 1 minute ago, Mono said: 72/52 is apparently 1.38, but that's just a minor correction. seems i have somehow some concentration/typing probs lately.... 1 minute ago, Mono said: So how could we account for the increase in wire surface that dissipates the heat then? It would be the same factor, 1.38? That is, we end up with "1/1.38 cooler wires" if we increase the wire diameter by 1.38, but the same power dissipation.. Yes. Also the thicker wire has more thermal capcity... By the insulation (not only electrical but also thermic) and the (almost) no air convection/airflow within the compartment were the wires are inside the final temperatures should converge? So the real needed diameters should be approved by real stress tests (2 hours running at nominal load at ~35-40°C ambient temperatures, ?5-10? minutes at peak load....). Such basic thoughts we do here should be just a first rough estimate to get something to start with... 1 Quote Link to comment Share on other sites More sharing options...
Mono Posted January 30, 2018 Share Posted January 30, 2018 11 hours ago, Cranium said: I was thinking that was what you are doing. I think you need to multiply your result by 2. No, all numbers but the last were ratios, and 2/2 is 1 , for the ratios it doesn't matter whether we look at radius or diameter. Quote Link to comment Share on other sites More sharing options...
Stanor Posted January 30, 2018 Share Posted January 30, 2018 do you know how much they want to sell us the Z10 in France? Come on, laugh well 1 Quote Link to comment Share on other sites More sharing options...
WARPed1701D Posted January 30, 2018 Share Posted January 30, 2018 2 minutes ago, Stanor said: do you know how much they want to sell us the Z10 in France? Come on, laugh well $3000! Twice what eWheels estimates. Bloody hell! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.