If you didn’t already know the VESC has built-in regenerative braking it can charge your battery when braking.
I also thought It would be appropriate to explain exactly what that is & how regen braking works, Then I realised I actually don’t fully understand the technical principles of how it actually works, Maybe Someone else can explain in detail how the Back EMF is used as a brake force, how it is created & controlled.
Anyway, This is my simple explanation as I understand it: The ESC stops outputting power from the battery into the motor, Instead the motor now turns from momentum as it rolls along the ground, it basically turns into a little generator. It starts generating its own current, known as Back EMF (back electromotive force) which is sent back into the battery just like a battery charger does.
For some interesting analysis on how much this technology can actually charge your battery read this article written by Justin from Grin Technologies.
So now to the actual purpose of this thread
In this thread I will explain how to set up Regen in the BLDC tool. How to configure the brake to make it perform the way you want it, Stronger or Softer braking force. More charge current less charge current.
Open the BLDC tool / Motor Configuration TAB / Motor TAB
These are the two parameters you need to change to make changes to the regen. “Motor Min (regen)” & "Batt min (regen)"
Displayed above is the default settings, these settings work great! The brake force feels really nice, it’s strong but not too strong so you get launched from the esk8.
One thing that confused me a little was the negative values & the wording of the parameters, specifically the “min” part.
For instance if you are using the SPACE Cell and want to maximise the lifespan of the battery and only charge within manufacturer’s rated max charge current of 4000ma (per cell) you may want to have a max charging current of just 12 amps (the space cell is 10S3P. 3 parallel groups X 4a Max Charge Current = 12A Charge current). So you would change the “Batt min (regen)” to -12
Motor min (regen) this is how much current you want inside the motor when using regen braking. If your motor has a rating from the manufacturer saying is is good for 40 amps you should then set this parameter to -40.
So how do these two parameters work together to control the feeling of the brake, the real life braking force you will feel when riding?
As I said before the default settings are great as they are, progressive controlled braking force that brings you to stop in a safe manner. But if you do change the parameters to meet manufacturer’s guidelines what happens?
Batt min (regen): If lowered, say to -12 from the default of -20 will reduce the force of the brake (most noticeable at higher speed). If increased above -20 will strengthen the brake force (most noticeable at high speed). Also it will charge your battery more.
Motor min (regen): if lowered from the default of -60 will reduce the force of the brake (at low speed brake force will not be changed much) if increased greater than -60 you get stronger brake force, also you might get much hotter motor if you do lots of braking at high speed.
Hopefully now you have a better understanding of how the brake settings work in the VESC and you can tune it to suit your electronics and your riding style.
