BLDC Setting for 2 battery setups

ESK8 Electronics
1

Hello to everyone first, I’m reading for some time and I’m getting a bit confused.

I would like to know what is the best setup in BLDC for braking.

This is my board: Enertion R Spec VESC from Enertion

Right now I’m using two different battery systems. To get a bit used to the board, I use right now just one 3S C45 4200mah battery. Later when I feel more secure on the board, I want to switch to 2 3S C20 5000mah in series. I tried the Batt min (regen) with -10. And the brakes felt very weak.

Now the questions:

  1. best current limits for both versions (3S and 6S)

  2. regarding voltage limits, is it important to change the maximum input voltage? Cause some say to leave it 42V

Thank you very much

2

Both of these battery setups are pretty low voltage for a vesc.

i think it would better to use 8s. limit torque with motor max A from 30-50A. brakes around Motor min A -30 to -45A batt min max goes by what your cells can do. I use 20-30A, min -8 to - 12A. Most batteries can charge at .5 - 1c.

limit top speed with erpm soft limits.

leave the input voltage at default, adjust the battery cutoff start/end to keep you pack from going too low.

3

But if I take the 2 3S batteries in series, I get at least 6S. That is still not sufficient?

But thanks for the tips. I will change the settings accordingly.

Maybe in the future I will add two more batteries then that are 5S. Can put them in Series for 8S and then the two groups in parallel for more amp

4

6s could work ok, but with the vesc 8s - 12s is where all the performance is.

but if you never want to go above 15mph, and you don’t mind give a couple kicks to start up, 6s will work.

oh and dont mix cells. if you are using them in series/parallel they should be identical. or you get :boom:

5

Thanks. I will go for a month or two with 15mph. This is still 24kmh. After that I can update the batteries to 10S or get a space cell to go up to 45kmh. The problem for me with the bigger batteries is the size. 6S LiPos are really thick.

Thanks for help

6

Don’t forget “battery cutoff start/end” parameters to save your batteries. “Battery cutoff end” min possible is 3 * 3S = 9 “battery cutoff start” a little bit high, like 3.3 * 3S = 9.9 I have both of mine little higher 3.2 for end and 3.4 for start. When you change your batteries to 6S you will have to multiply by 6S instead of 3S

I think is better to start with one 5S battery and later add 5S battery in serial. 3S is too low

7

I chose 3.6 volt as first and 3.5 as second cut off. So by your recommendations I can go lower than 3.5?

Regarding the soft motor cut off: I saw on the YouTube channel from ESK8 support that there is no need to use it.

What is your opinion about that?

8

I am not an expert. I know the min possible in this kind of batteries is 3.0. Below that is not good for the batteries. So 3.5 is safer than 3.2. If you don’t have a BMS in your batteries I thing your settings are better than mine.

I assume that you have choosed 3.5 * 3S = 10.5 and 3.6 * 3S = 10.8

9

My batteries shouldn’t go lower than 3.2. So I set the first step at 3.5 and the vesc cut off at 3.3

So far I only did 5km on the board. But thanks for the help. The board runs really nice.

Top speed I don’t know yet as I need to get better on it. It get’s whobbly for me above 20km/h. But that is still far of the top speed. I guess with the 6S system it will be around 30km/h or 18-20mph.

Btw: even with 6S it starts out of stand and I don’t need to push. Starts really fast.