Hello electric skateboard builders! I have recently finished my very first esk8 build and have now taken it out for a few runs, however I am running into a couple of problems.
The first problem i’d like to address is the acceleration from a full stop. I have noticed that my (dual) motors (sk3 260kv brushless-outrunners) jutter or stall when i try to slowly accelerate from a complete stop. I am not sure weather this is due to the (kv) of the motors being too high or something to do with my vesc settings.
Heres a video
The second problem i have noticed is that whenever i connect the circuit in the board to turn it on, a blinding spark goes off. this is kind of discomforting, and i was wondering what could be causing the problem and if there are any solutions.
Here is a video
My hypothesis is that the voltage stored at the end of the connector is built up and when the connection is made, such a small surface area is initially touching, the electricity has nowhere else to go but out. using a volt meter i noticed that the energy at the connection is something like 30V and maybe it is because of the large amount of energy? I have no clue, this is my first time doing this…
Here is a picture of my circuit diagram and the actual circuit
On the bright side, i have achieved a top speed somewhere between 35 and 40km/h, and got a time of roughly 61 seconds for a full lap of a 400 meter track.
Hey @JoJo nice build! For your first problem with the stuttering, I’m not sure about because I don’t have a geared setup, I have hub motors, but it might be do to your VESC settings. But your second problem is due to the capacitor banks on the VESC’s. When you first plug it in there will be a large spark because it’s drawing an immense amount of current but for an insanely short period of time. Like @wmj259 said you could use a Vedder Switch witch would solve your problem. You could also you XT90 connectors witch I guess have some sort of resistor inside of it to slowly charge the capacitors and prevent that initial spark. You could also take a look at my MOSFET switch thread were I have schematics on how to build yourself a switch as well.
Or you could use a xt90 anti spark plug.
Anyway, the benefit of an anti spark switch is that you can use a good looking switch maybe even with a led (ring) to power your board.
The spark is basically the result of the requested charge current for the capacitors of your vescs
The stuttering or cogging is a side effect of using BLDC, to prevent that kick off before you apply the throttle. Another option is to use FOC, though I wouldn’t recommend without some research, since some people have had the DRV blowout on there VESC.
Let me just start out by saying that I am not 100% sure that what I know is correct but I’m going to give my 2 cents anyway. I completely agree with what @mortorojo said about preventing the cogging with a push start then hitting the throttle. The cogging could also be because you are using unsensored motors. These will often give a rough startup with a lot of cogging from a complete stop. I believe that sensored motors give a much smother start from a dead stop. That is just my opinion but as I said before, I could be wrong
Does it include the circuit board like the one posted by JdogAwesome? Or its it the switch itself? Earlier I tried to use a 5-10v “garden bender” switch but I think it fried.
Great idea. I’ll be sure to push start. Do you know there I could find some sensored motors for around the same price point as the ones I currently have as a future upgrade?
Yeah pretty much any conventional switch you find your going to kill because of the amount of current these boards draw, really your only option when it comes to EBoard switches are either MOSFETs or XT90’s.
You don’t need sensored motors, most people don’t use them because the sensors break or cause other problems, any board you find pretty much is going to have cogging problems at the start, that’s just how brushless motors work. And they can also cause problems at high speeds because the hall sensors can’t reset fast enough. And sensored motors are a lot more expensive as well as very hard to find.
That’s good to know about the switches, I was just about to go buy another one
About the motors, just a small push at the start is all I need to fix the cogging?
About the motors, just a small push at the start is all I need to fix the cogging?