How is HP calculated on electric motors?
Thereās a formula on google. You should have all the info you need to get the data
it is watts/(pirpm) but you also need to convert that from newton meters to ft lbs. rpm is kvvolts and then you need to convert for the circumference of the wheel youāre using.
Ok , actually allready had a converter on my phone ,ā¦2700w 6374 motor =3.62 hp.
You canāt just divide watts by 746?
that is about what i got.
It depends on what voltage you are running as well
Slow down there bullet. 
22.2v is 6s, so 44.4 is 12s. You will need DIYes or similar 12s opto ESC, or VESC, but the VESC will be limited to <200kv motors on 12s (youāll kill the DRV chip w/ 245kv motor on 12s). In fact, @Chaka has a great writeup and suggestions on VESC motor combinations to avoid going over 60k ERPM which seems to be a better limit to avoid this. So if you are set on 12s down the road - iād look at the 149 or 170kv options. 190kv also may work, but be careful when fully charged.
I prefer VESC, but the simplicity of DIYes 12s opto ESC is enticing as well. I just havenāt tried one to comment/compare w/ VESC.
For a big guy and wanting hills - yes you will need dual motors. Gearing i would start running some calculators on gearing - but donāt go below 13 or 14t on the motor gear (youāll get skipping on hard braking and later acceleration) - at least on 9mm belts. For a bigger guy like yourself i might start w/ 12mm and possibly even 15mm wide belts - increased surface area and contact area will help.
Since we are both bigger guys, iāll share some planned setups to compare:
83mm wheels - 190kv - 6s - 14/36 (motor/wheel) = 15mph (ish) 8s = 18 10s = 23 12s = 30
I might gear down a bit more if possible w/ DIYes 40t wheel gear - same setups:
83mm - 190kv - 6s - 14/40 = 13mph 8s = 18 10s = 21 12s =25
Smaller wheels are better for hills and lower speed. I really like big wheels though. I like to ride over rougher roads and a similar setup w 97mmās:
97mm - 190kv - 9s - 13/40 = 20mph (on 12s = 27mph)
Hope this helps and good luck!
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Iāve never ridden one motor except when one of my pair isnāt working when the canbus comes disconnected again. Iāve never noticed any torque steering or any il effects but itās very underpowered on one. How badly does using one strong motor affect handling?
Non-issue for me. Iāve ridden more single setups than dual. But i donāt expect hills or drag racing acceleration. I have another dual setup in the works for next boards.
No spinning or issues iāve noticed. My buddies boosted dual+ is smooth, but iām likely not pushing it hard enough to tell the difference besides just better acceleration.
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based on that iāve decided on 3 2s 5000mah batteries wired in series to get 15000mah and 6s with a single Turnigy Aerodrive 245kv now however iām not really sure what esc to go with. do you have any recommendations for good escās. also braking will be done by a disk brake and the motor will be connected to a fly wheel so that only forward motion is transferred to the wheel.
If you want to connect your batteries in Series, this does not increase the capacity of your cells, you will remain with a 6s 5000mah pack. As for esc the vesc is pretty good?
How less effecient is 2 motors compared to 1 ?
I donāt know for sure but I donāt think it will have much of an affect. It comes down to youāre moving a mass distance X, and if you use one motor, that motor draws A amount of amps and you put in a total amount of work, W.
You add a second motor to the mix and youāre still going the full distance X, your mass doesnāt change (technically youāre adding the weight of the motor and VESCs plus miscellaneous shit) so the total work W, which is defined as Force x Distance. Force, is Mass x Acceleration, assuming the change in mass is insignificant and your riding habits remain the same, therefor use similar accelerations, the force exerted by each motor should be half of that of just one, meaning youāre drawing less amps per motor, or half.
So the total force also remains the same. So in the end, two motors just translates into better traction and if we ignore the losses of friction and electrical losses of resistance of two set ups, you end up around the same place, but drawing less amps per motor, keeping the system cooler and amp drawing to a reasonable amount per VESCs. So there are other benefits.
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I think the pulley belt system being doubled will give double the losses there. Twice as hard to physically push a double pulley as a single
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I completely agree with that, but I donāt think these minor losses will be significant when compared to that of air resistance for example.
For a large body, humans qualify as large bodies, the air resistance is a function of K*V^2. Where k is a constant that is dependant on many things such as shape/aerodynamics and the medium in which youāre traveling through, in this case air. And V is the velocity at any moment in time. The resultant of that is a force btw, so you double your speed, you quadruple your air resistance which is a drag force on you. You go from 6mph up to 24 mph and thatās 16 times the air resistance. And once you pass a certain barrier it transforms from a squared function into a higher order function making the smallest increase in velocity that more difficult to achieve, until you hit top speed essentially.
The inefficiencies of a little more rolling resistance due to an extra motor and belt on there really wonāt make a huge difference here are it will more or less remain constant when compared to air resistance. And especially when you consider the benefits added. Like increases in acceleration, braking, safety of having some redundancy, and better traction.
Hereās an example for rolling resistance, your pulley resistance in this case, for a car that weigh 1500 kg.
Do you see the magnitude of the coefficients? One, two, three percent losses for a CAR with pneumatic tires, urethane wheels have less losses than that even.
Hereās the link to the site. http://www.engineeringtoolbox.com/rolling-friction-resistance-d_1303.html
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Not true actually. You donāt see much loss because while thereās twice the resistance of the belts, half as much power is needed to drive the board. It can actually save you power if you have a lot of load such as going up hills or if youāre a heftier rider.
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Ok. if ur motor is smaller and put under too large a load, like a hill as u say, itāll have a lot of copper losses, and be more inefficient, but if a single motor is large enough on a board, rare, it wouldnāt experience that. So Assuming no greater electrical losses from too small a motor itās back to other losses
The example above for a car is new to me but bikes I remember rolling resistance losses were finally superseded by wind resistance at 15mph. Thats a more typical speed for a board. Considering how thereās so much more rolling resistance on a belted or double belted board than a bike Iād think those losses would be more significant at an even higher speed. Wind resistance can be huge but running a double belted board at only maybe 20mphā¦I wonder the losses. There must be someone here whoās done comparisons
Thereās potential to test this theory. Simply use the same set up, once with one motor and once with two. The test, reach 15mph for example and once you cross a line on the ground, which will be our start line, let go and coast to a stop. Measure the distance. Repeat with 2 motors, keeping all else the same. If there is a significant difference in rolling resistance then there should be a significant difference in distance as well (presumably twice the rolling resistance meaning half the distance if thats the only force acting on you and the board). Keeping it under 15mph will ensure that rolling resistance plays a larger role than air resistance and then maybe try it 3 times with each set up for a larger data group.
What would be interesting is doing this with a belt drive and then a hub motor and looking at the differences between those two set ups.
Yea some simple experiments would answer all the questions. Anyone with a pair of strong motors could just compare them to running one of them solo and disconnect the other belt to see the differences in watt hours consumed to distance on a flat course.
Iād like to compare hub motors. Or one hub motor. In theory one strong hub will get the best range ā¦assuming itās big enough. But thatās talking just about potential efficiency and thereās other benefits to running dual of course