someone said 7$ per cell so I assumed 18650 li ion batteries
you didnāt say where you got them fromā¦
whoops was thinking about how can i control lights for my skate with vesc and ackmaniacs app and an hm10 module sorry
anyways its nkon
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Yeah I was compiling code so was in highly academic mode 
Really if you grok Ohmās law though and get that voltage is the electrical potential/electromotive force that gives rise to a current based on the resistance in the circuit thatās all that matters. So amperage isnāt anything but that flow and isnāt something you really āapplyā rather something that falls out of the resistance and the voltage being used. Also extra bits basically saying power loss in components is related by the square of the amperage so 5amps adds a 25x factor (5^2) in that equation whereas 10amps adds a 100x factor (10^2) in the power loss equation so you ideally want to deliver power at higher voltage. The final part was trying to give some links that explain how the voltage that gets to the coils ultimately drives the amperage in them and the strength of that amperage also relates to the strength of the magnetic field.
Anyhow just figured Iād drop some of my favorite academic sources here, glad you got something out of it.
Good thing is with the background in quadcopters weāre using almost the same exact setup with regard to controlling the flow of power to the motors and controlling the rate of firing of the coils to keep the motor spinning or get it spinning faster/slower.
To get away from the academic stuff and physics fundamentals ultimately more strength in the magnetic field means it will have more force to drive the motor/wheel around and push you forward.
To try and relate to your example in esk8 terms: 90kg rider+10kg skateboard 6374 149kv (190kv seems a sweet spot really for most riders/applications) 50A continuous 240A burst VESC 4.x or above is a good option for controlling the motor and delivering power from battery 83-90mm wheels with a 16T:36T pulley ratio is typical = a board that will go somewhere in the 20mph-30mph range and gets about 1km for every 10Wh of battery (higher voltage higher efficiency)
You can limit the actual amperage used in the VESC configuration. Last night I compiled the new VESC tool on my computer (didnāt want to sign up to download the prebuilt and like to build stuff myself) and got the new metr.at app where I can select āmodesā to limit amperage to 10A or 30A or 60A depending on rider ability or if Iām just cruising vs testing top speed/acceleration. Without modes I was just on 60A all the time which was sketchy especially if letting someone else try my board, I never actually would draw 60A most Iāve seen was around 20A at 40ish Volts but Iām also only about 55kg (120lbs)
search for esk8 calculator quite a few out there to help you try and calculate actual values for different rider size, grade, gear ratio, wheel size, motor, battery, but lots of variables just like quads so itās hard to just give a direct answer without a very clearly defined set of parameters (even then calculation never completely matches reality).
The calculator seems more geared to street wheels averaging around 80mm sized wheels. Iām not getting a good reading with 8 inch wheels, plus not to mention my weight plays a big roll. Like you said, calculated number vs real life number donāt ever really matchup.
As soon as my board comes in this week, I will be documenting and testing different scenarios.
Yup best we can do is guess and check and post more data about real world conditions. Itās both the plus and the minus to doing things yourself and working with relatively new components.