bms per votol em150sp

[GianlucaO]

Hi, I bought a QS 138 90H 4kW motor kit with em150sp controller. The seller says that to get the required maximum speed (100kmh with 10 "wheels) the engine absorbs 86A continuous.
I currently have a 6S40P 22.2V 100Ah battery with bms 120A continuous/250A peak (INR18650 25E C cells) that I have been using for two months with the original 18V 1.5kW nominal, 3kW (peak) motor. Original motor absorbs around 130A at top speed and 210A during the hard acceleration (peak istantaneous over 300A). All tested with an amperometer DC.


I opened the battery because I want to rebuild it at 20S12P 72V30Ah and was wondering if I can get the required current from the motor and controller.


Searching for the code of my lithium cell on google, I obtained the manufacturer's data ( https://it.aliexpress.com/item/4001...82902508321701702241d25081956170131d-160d1605 ):




How many amps can I get from these cells in 20S12P configuration? How many amps can the bms votol em150sp withstand? I think it's 150A, right? Do I need a "common port" bms to use the regen function in braking? how many continuous and peak amps must the bms be in order not to break the controller in my setup?

Thanks everyone for the help, I can't do it alone.

 

[larsb]

Votol em150 and qs138 70h can take 300A battery for some time so you’d need a better cell if you want to push the 90h motor. 20s30p battery like you'd need is 600 cells and will be too large for most bikes or even motos.

I’d instead buy a used automotive pack or build a pack with one of the new 21700 high current cells (like molicel p42A)
https://eu.nkon.nl/molicel-21700a-4200mah-30a.html

If you aim for 300A both for battery and bms you’re in the right territory (off course you can go with less but this will have both full performance and a nice reasonable loading of the parts in normal use)

 

[GianlucaO]

OK thanks, but at the moment I can't spend much on a new battery and in any case I have these cells to use (they have few life cycles as I have used them little on the scooter). What current can I reach from these cells in 20S12P configuration? Can I use a continuous 90A bms? Or should I choose a less powerful one so as not to damage the cells? For example 60A would be fine? Do you think bms are good in links? Do you have others to recommend? Do these balance the cells when charging? Eventually I realize that the bms is too powerful, can I change the amps via bluetooth to the bms in order not to damage the cells?

Are these bms ok?
60A:
https://it.aliexpress.com/item/1005001406372932.html?spm=a2g0y.12010612.8148356.3.2e1e5014dOle7b
80 or 100A:
https://it.aliexpress.com/item/4001322690751.html?spm=a2g0y.12010612.8148356.4.47337a2385lL0T

 

[larsb]

It’s as simple as 12*12.5A, normally a bit more for short bursts current (12*20A in this case) so you can probably use 150-200A.

Current is not supposed to be regulated by bms except for during fault condition, it is regulated by setting in controller. A BMS shutdown can sometimes damage controller so it’s to be avoided.

Therefore you want bms with capability and setting above your max use current. i’d get the 300A smart bms from icgogogo store on aliexpress and set it on 200A if you want to run 150A max current setting in controller. I like this ”smart” bms as it’s programmable and you can calibrate it.

All bms must be capable of balancing, otherwise it’s not a bms.

 

[larsb]

I reread your post and i see a possible problem: why is the old pack built with so many parallell cells? Could be current capability of the cell is much lower than in the spec. Therefore I think your cells might not be capable of enough current in 12p but only way of knowing is to test it.

If you test voltage drop at 100A on the configuration you have and calculate this into 20s12p configuration then you’ll know.

 

[GianlucaO]

Before, I used the battery with the 18V electric scooter that absorbed over 300A in peak for short moments, while at normal speed about 200A. The engine was a rated 18v 1.5kW, 3kW peak. The scooter originally had 3 6V 100Ah Ni-Cd Saft batteries but now after 20 years they have little autonomy, about 15-20km maximum. With lithiums I got up to 58km of range with much stronger acceleration. Original 18v reached 45kmh, now at 22.2v even 65kmh.
So it was assembled at 6S (22.2V) 40P (100Ah) to match the original battery.

At the moment I have replaced the motor with a brushless qs motor with nominal 4kW, 12kW peak and 20kW for short periods matched by the manufacturer with Votol EM150SP and therefore I would like to use my cells in 20S12P (74V 30Ah) because they are practically new, I used the scooter little, about 10/15 full charges.

So should i choose a bigger bms than the controller? I believed the opposite. So do you recommend a 300A smart bms set at 200A, and then set the votol controller to a maximum bushbar current of 150A? it's correct? Do you know if the votol needs to "precharge" with a resistor or not?

 

[larsb]

Yes, that would be about ok if your motor can take it. 72x150 is close to 11kW

All controllers need a precharge when connecting battery. I just leave battery connected so the precharge is not part of my system

 

[GianlucaO]

But the bms 300A have a sparkle current too high: 1000A+-200A....or i need a sparkle current of 300A, so i take a 100A bms with 300A + -50A peak?

 

[larsb]

Forget the bms numbers. You program the setting you want to have. 300A bms will be capable, have lower voltage drop and less heating.

Again: bms should only cut current during critical overcurrent condition or critical low voltage. Since your cells are speced to take 20A peak (then your 12P battery in theory can output 240A) you’d need bms that can take this current or else it will be limiting your system.

 

[GianlucaO]

My cells take 12,5A max continuous. 12Px12,5A=150A max continuous. So i can buy the bms 200A continuous?

At 150A i have 10.8kW. Is more than the 86A i need to obtain the top speed of 100kmh. QS seller declare motor need 86A continuous for max speed. Of i choice the bms 100A i get the top speed? (100>86)

86A is 6,2kw
Bms 100A get max 7,2kW. Its correct?

 

[ReidSchwartz]

Hello All this is my first post on the forum. Little background I'm a student starting an electric dirt bike project. I've read through many forums and I think it still needs to be settled?

WHICH CONTROLLER IS THE BEST MATCH FOR THE QS 138 90H?

I've heard the votol controllers cause problems, I saw Zalo used a sevcon 350A, and I've been recommended a Kelly KLS7275H. So which is the best? Has QS Motors finished their testing for the best controller yet?

Thanks everyone for your wonderful contributions on this forum

 

[larsb]

The Votol 150 is a great match when it works but it is not 100% stable, some users have gotten issues but since QS honours the warranty i still think it's a good choice.

Kelly on the other hand.. KLS controllers are not good. I've personally had five stop working and i did not get warranty replacements.

If only the Votol EM200 was OK i'd go with that because the 90H motor will need a higher output controller than the 70H to get all performance out of it - EM200 still seems to be doubtful in performance so i'd not risk it (if QS motor does not explicitly recommend EM200 to you)

Sevcons are out for me as they are hard to program and you most likely will have to do a new controller profile for this motor.

ASI BAC8000 is what i'd look at if you have enough funds for it.

 

[ReidSchwartz]

I really hope that Votol works out the bugs because I don't want to spend 3x the price of the motor just on the controller. I'll keep checking the forum to see if the em200 gets recommended.

 

[larsb]

Controllers are what breaks. After five years of using them daily i think quality controllers are worth paying for.

 

[Sattva Ram]

I am also before buying the 90H 4000w qs with the votol controller for my aprilia rs50 conversion. I am vacillating between the 200sp and the 150sp. I cant quite interpret what the peak phase current the boost current and rated current mean. Can someone enlighten me as to what the real world numbers are. What's the absolute max amps of each controller? And what's the continuous? The maximum amp for the smart BMS is 400. Does it make any sense to buy the 200SP controller because maybe the bms will be the limiting factor anyway so in that case the 150sp will suffice too cause even that reaches the ability of the bms. I am looking for 120kph top speed. I am also planning on installing a computer fan into the motor so maybe I can churn out some extra performance out of it.

Does the 150 and 200 refer to the continuous amps? Because if so then I guess 150 is more than enough, even 150 Amps continuous would overheat the motor by my estimation.

Also could someone tell me if the regen is efficient with the votol. I never had such a serious build as this I only built a tuned greyborg so far with a 72v greentime controller but the regen in it is dismal maybe 50% of the braking energy goes into the battery and the rest heats the motor like crazy. I dont want another controller with inefficient regen especially for this price.

Thanks

 

[larsb]

Most of the questions are in the votol thread already. I suggest you read it.