I have not looked into this specifically, and I have yet to get my first E skate, but has anyone looked into how power factors can change the relationship between current, volts, and watts? Anyone who understands AC motor theory and inductive loads will be familiar with power factor. It’s my assumption that this could play a role in brushless motors, since all motors are an inductive load. Though these motors do not use a true 3 phase sine wave per say to operate, I would Imagine the current waveform is still affected by the inductance in the motor, and a lagging power factor is developed between the pulsed waveforms. In otherwords the pulsed current peaks and the pulsed voltake peaks become seperated, described as a lagging power factor. I am assuming this is worse at a lower duty cycle than at a higher duty cycle, so the power factor would be worse at a lower duty cycle, lower loads, or erpm. In The AC world we call the relationship between measured current and measured volts VA, or volt amps, also called apparent power. This is not watts, It always measures higher than watts. True watts are the comparison between the instantaneous amount of current to voltage. With a lagging power factor the peak of the current lags behind the peak of the volts, so when you multiply them together at there instantaneous position you have less watts. My assumption is at this point, setting the motor max has to do with the current seen in your motor. Because of power factors, this measurment will be higher than the calculated current from watts. Understanding Power Factors and AC motor theory can be tricky. Brushless motors and the accociated hardware to run them, seem even more difficult to understand, being that there are relationships to both DC and AC. I am not pretending to understand brushless motors, this post is an assumption on my part, but I thought I would throw this in this thread. I do understand AC motor theory reasonably well though.
Agree with 1
Not agreeing with point two.
If you raise the motor limit you get to a point where you don’t hit any limit because your motors don’t draw enough amps. Perfect.
Or you burn your motor.
In a well balanced system you might not hit any limits. And then your theory is rubbish.
One reason the VESC is so good is because it implements very sophisticated Voltage/Current measurements. What your little cheap watt meter won’t see is spikes. It just doesn’t sample fast enough. It is before the big caps too. If you want to really see what happens use this:
Here is the thread on ES for the project: https://endless-sphere.com/forums/viewtopic.php?f=35&t=68975&start=125
Log what the VESC sees and run it through Matlab or any other software of your choice. Then look at the code and see why it reacts the way it does.
Exactly!
Do you hook up AC or DC? If you hook up DC ohms law will eventually apply and the winding resistance will be the only resistance.
If you hook up AC you have the inductance fighting quick changes in current and your resistance is far bigger than the pure wire resistance.
You can calculate all of this.
So under no circumstances you will have 400 amps.
I would suspect that in hummies setup of 70amps battery limit and 70amps motor limit none of these limits are hit.
Wow that’s awesome! is it open source? I’ll try it soon (I have an HM-10 lying around even if most of the users use HC-05) ! The UI is in german, I could translate it if it was open. I couldn’t find a github link of that but I found another project from that post ( https://github.com/bchiu/Traction/blob/master/README.md ) that looks good, at least the UI looks very good, it seems a bit complex/advanced (using react and protobufs) but that can be a good thing if it’s complete / stable.
Absolut rubbish! A motor is not just a wire and you can’t use ohms law!
Test it! Hook up hummies board to a PC and monitor motor amps. I reckon they are below 70 amps.
I think there is, I think the VESC limits the max acceleration you can have and this creates the impression of a hitting a greater acceleration spot for 1/2 seconds. When you are full throttle on a slight hill or on a flat but still not at top speed there’s a treshold point, before that point your VESC is using all amps at/close to you motor max and then the mechanical resistance becomes less thus the VESC will still supply max amps but you’ll accelerate more than the VESC limit settings (that’s when you’ll get more acceleration). Then the VESC will notice that the acceleration is over the limit and it will limit the current to prevent over accelerating even if you are not using max current. I believe it works like this.
Solution: modify Vedder’s code to release that current more softly or check max acceleration more frequently or simply use less throttle 
@devin Have you seen Vedder videos with logging overlay like this? We can see the data but not the throttle position unfortunately. Check at 2:40
BECAUSE … A… MOTOR… IS… NOT… A… WIRE!
In your example you would produce 40kw LOSS!