Jacob when your battery is full charge 41V and you brake hard , its does’nt trigger over voltage and cutt off , since your Max is only 42V ??
how do i know what settings i can used for what i have battery 8.8AH 24V 18650 Lithium-ion and 1200W Brushless Hall Sensor Direct Current for the motor and how would i go about adjusting and changing the stuff. is there an application?
Why is there a max voltage?
The two low voltsge cut offs are very important if u don’t use a bms and will slow u than almost stop u when they are hit and not damage ur batteries. U probably know
I dont know specifically those 18650 and I think u can drain them down to about 3 each but look at a discharge graph and find where they drop off.
is this true if you don’t have a BMS?
What vesc setting stops it from over charging your battery? or do you just assume regen from braking is so small that this is not a problem
Sorry for reviving an old thread, but I rather do that then start a new one about the same subject 
I wonder how the VESC will cut if I would use this max voltage setting as a protector for the battery?. Will it ramp down the regen amps, or will it do actual short cuts or will it cut of and not come on again for many seconds?
I ask about this because I live on a hill, so there for I am afraid to overvolt my pack to much when going down my 8 degree 400 meter long hillroad. I fully understand that cut = means no brakes 
Until now I usually do not charge my board at home, I use it for commuting to work, and charge it at work so I do not have the hill-problem with a fully charged board.
One time I did charge the board fully (4.2v per cell) at home and then went out riding with my family. After just 30 seconds into the ride, my son went in front of me with his bike and I had to brake, the board braked for a second then it let go and died on me = no go and of course no brakes… I jumped off 
After checking the electronics I found that the VESC was dead… It was a Flipsky dual FSESC4.20 and one side of it was dead. It looked like the BMS had cut the power to the VESC when I braked, and that cut killed the VESC…
So I would much rather prefer to have the VESC ramping down the brakecurrent or do “ABS-like” cutting wile braking then to have the BMS cutoff and break the VESC so I have no brakes at all…
What do you other guys do, are you running the leads straight to the VESC, not through the BMS and allowing higher voltages to hit the cells during short bursts of regen? How high voltage per cell do you allow, 4,25-4,35V ?
Thanks in advance!
Depending on the battery chemistry and how fast it’s charged it might get to 4.35 but could drop down to 4.2 in moments. You can charge ion cells much higher before bursting into flames
In that case I would charge the battery to 4.1V ; to give me more time for a emergency brake, full stop…Also you will get longer life span of you cells…charging at 80% it’s not bad at all…You could also get a bigger battery, so you do not loose much range by charging at a lower capability…
Thanks for the responses!
Today I have a 12S3P 10Ah battery that I made out of used Sanyo 18650GA (3350mAh, 10A) cells. It gives me about 40-50km real range with my type of riding, whitch is good to me, but the cells are not new, they still have the capacity, but not the current output, so they sag alot during power output and spike during input (regen). When charging at home, I charge only to about 3.80-3.90V to be able to handle the downhill. But when charging at work I charge to about 4.13-4.14V.
During winter I will build a battery out of brand new Molicell 21700-P42A cells (4000mAh, 30A). I have already ordered them
It will be the same setup = 12S3P because that fits my board very well. The P42A cells have at least 3x times the current output compared to my old cells (and 12Ah in total = 50-60km range), so I assume they will sag less and spike less = I can charge them higher at home because they will spike less going downhill. But at the same time I will probably rise the regen current setting (battery Min) due to the P42A cells ability to handle more chargecurrent, so maybe they will spike some anyway… Only the real world test will show.
When going down my 8 degree hill at about 30-35km/h, at full brake the regen current maxes out at 10A that is my Battery Min setting. That brake power Is not enough to slow down the board at that speed, but enough to stop it from accelerating more. That is 3,3A per cell, and that is what they can take in chargecurrent read from the specs. The P42A are supposed to be able to handle 8,4A per cell = 25,2A in regen/chargecurrent. I guess I would use 10-15A to keep the board at a safe constant speed downhill, and more if I must brake to a stop. Only the real test will show how muck the cells will spike.
Do you think I can safely test to set the Input Max Voltage low to see what happens during braking (on a flat road) or do you think that there is risk of braking the VESC by doing so? I assume the VESC should be able to take it, but I do not know.
1 Like
I’ve always wondering people with huge motors and fast setup going above 60kph(trampa riders lol)… how do they stop? How come their battery pack can handle that kinda regen…
the manufacturers state a charge current intended up to full voltage but if youre charging for shorter periods and when not as close to full you’re able to charge at a much higher rate.
Ive thrown a 3v and a 4v 30Q cell together in parallel and I cant even say for sure either cell increased temp but minutes later they were close to balanced and a lot of current had been transferred. maybe a more revealing test would be throwing a 4v cell in with a bunch of 4.2 cells to see if it gets warm.
big motor or little would matter very little.
That is a good question.
Bigger motors or higher speed will generate higher amps to the battery as your wrote. Maybe they run with much larger capacity batterypacks, if they don´t do that, I guess they will just abuse their batteries then swap them out after a while.
From what I can se on Trampas webpage about batteries, there is alot info about how many lipo packs you can put in their batteryboxes, not li-ion. And some lipos do come with an 5C chargerating. If that is a good real working thing, I do not know, but 5C into a 12S 16Ah pack is 80A of regen power, that is alot more stopping power than my 10 or 12Ah li-ion batterypack (my old one takes 10A and the new will manage 25A regen current).
A bigger motor won’t increase the charge current and 95% decided by the kv. The higher the kv the more amps produced for the same braking performance.
the manufacturer’s stated charge rates are very conservative and you can do much more for short periods without risk especially at lower voltage. They state such a rate as intended continuously all the way up to 4.2 volts which is when it would be most detrimental
Thanks for the reply! You say size does not matter then 
Okey, so beltdriven higher kv motors will generate more current compared to hubmotors that are bigger with lower kv. But beltdrive make the motors geared down, so do they generate about the same current because of that compared to directdrive hubmotors?
I think it will produce amps when braking the reverse of how it would perform as a motor so a bigger gearing will require less amps to drive the motor and also will produce less amps when used as a generator.