Cheap(ish) BMS from Aliexpress

[Alibro]

Hi guys
I'm not in any hurry to sort a BMS but was browsing (like you do) and came across this 96S BMS from Aliexpress and was wondering if anyone here has tried it or know anything about it?
https://www.aliexpress.com/item/1005001 ... web201603_

[LRBen]

I used an aliexpress ANT BMS for my 48v quad bike. It died with a charge mosfet error after about 4 months and maybe two charge cycles.
Currently using a more expensive Daly BMS from aliexpress for that bike now.

But I'm not sure I would trust anything from aliexpress for a car sized battery.

[arber333]

I have found this active balansing BMS
I think i will buy capacitive version for 8S just to see how they work.
https://www.aliexpress.com/item/1005002 ... 0031639067

Then there is inductive Active BMS too.
https://www.aliexpress.com/item/1005002 ... 0006025309

[SciroccoEV]

No vehicle BMS should ever disconnect the battery under load, unless it's a safetly critical situation (big overcurrent due to a short for example).

Most of the cheap systems out there are using BMS chips intended for cordless power tools and assisted bicycles, but with massively oversized Mosfets.

If you got an cell over-voltage reding during regen (due to a faulty sense wire for example), then disconnecting the battery could potentially result in a blown controller. You suddenly nowhere for the regen energy to go and depending on just how fast your control loops are, you may not catch the over-voltage in time. If the BMS simply signals the controller to cut back, then you should be fine.

I bought one of the small Chinese BMS baords (25Amp) and then modified it with an external shunt and the charge/discharge mosfet signals routed to optoisolators.

[arber333]

No vehicle BMS should ever disconnect the battery under load, unless it's a safetly critical situation (big overcurrent due to a short for example).

Most of the cheap systems out there are using BMS chips intended for cordless power tools and assisted bicycles, but with massively oversized Mosfets.

If you got an cell over-voltage reding during regen (due to a faulty sense wire for example), then disconnecting the battery could potentially result in a blown controller. You suddenly nowhere for the regen energy to go and depending on just how fast your control loops are, you may not catch the over-voltage in time. If the BMS simply signals the controller to cut back, then you should be fine.

I bought one of the small Chinese BMS baords (25Amp) and then modified it with an external shunt and the charge/discharge mosfet signals routed to optoisolators.

You are missing my point. I will add one 8S board to my DIY BMS (16S) which keeps track of single cell voltage. I will then leave it inside and observe difference. Should be like fire and forget add on...

[arber333]

I have found this active balansing BMS
I think i will buy capacitive version for 8S just to see how they work.
https://www.aliexpress.com/item/1005002 ... 0031639067

Then there is inductive Active BMS too.
https://www.aliexpress.com/item/1005002 ... 0006025309

Ok, i ordered one 16S board of latter inductive BMS board. It is supposed to balance with 1.2A. I choose inductive type over capacitive type because it takes less space. But i am also willing to test the larger capacitor variant. That should balance at 5A which is a lot!
I think 16S is best for me. At least i have some cells to draw my average from. If this is successful i will order 6 boards and complement them to my BMS board.

[vwbrady]

Ok, i ordered one 16S board of latter inductive BMS board. It is supposed to balance with 1.2A. I choose inductive type over capacitive type because it takes less space. But i am also willing to test the larger capacitor variant. That should balance at 5A which is a lot!
I think 16S is best for me. At least i have some cells to draw my average from. If this is successful i will order 6 boards and complement them to my BMS board.

very curious to see how this works out.

[Alibro]

I used an aliexpress ANT BMS for my 48v quad bike. It died with a charge mosfet error after about 4 months and maybe two charge cycles.
Currently using a more expensive Daly BMS from aliexpress for that bike now.

But I'm not sure I would trust anything from aliexpress for a car sized battery.

I've been using an ANT BMS on one ebike and a Daly on the other for over a year with no issues. Whether I would trust one with my car pack is a different thing. Maybe If it was only monitoring the voltage of each cell and not controlling the load I might consider it.
Tony from Vorteks on Youtube is the expert on ANT BMS

[arber333]

very curious to see how this works out.

I put this one in my car on one of the more varying cell voltages . I will inspect voltages after a few charges and drives.
After the first test for several hours it seems that it takes charge from adjacent cells to top up the lower cells in 16S module. This slowly depletes the cells of voltage (in the range of 0.01V) but complete module voltage seemed to remain at 61.8V. Current involved that i registered was in the range of 0.8A to 1A. While i left balanser connected overnight it seemed to correct voltage on once cell from 3.85V to 4.01V and there was still 0.2A flowing. It seems this to be a real deal.

EDIT: I will run this in my car for a week and compare to adjacent modules.
It seems modules can be cascaded.

[Alibro]

very curious to see how this works out.

I put this one in my car on one of the more varying cell voltages . I will inspect voltages after a few charges and drives.
After the first test for several hours it seems that it takes charge from adjacent cells to top up the lower cells in 16S module. This slowly depletes the cells of voltage (in the range of 0.01V) but complete module voltage seemed to remain at 61.8V. Current involved that i registered was in the range of 0.8A to 1A. While i left balanser connected overnight it seemed to correct voltage on once cell from 3.85V to 4.01V and there was still 0.2A flowing. It seems this to be a real deal.

What do you think would happen if you have several of these overlapping?

[vwbrady]

I was thinking the same thing. putting 6 of these on a 96S pack could be interesting but of course would not balance between those 16 sets. overlapping could solve that. hmmmm

[Alibro]

WOW! I just found this in Aliexpress
https://s.click.aliexpress.com/e/_Ad6qG0

Phew, I checked again and this is for 5 of them.

Is there any drain when they are not balancing?

[Alibro]

I found another that goes up to 21S
https://s.click.aliexpress.com/e/_A7JhBa

Buy 5 of these for around $280 and you have enough spare capacity for them to overlap

[vwbrady]

I wish these also provided cell voltages though. Balancing is great, but we need BMSs that will tell us things!

[Alibro]

I wish these also provided cell voltages though. Balancing is great, but we need BMSs that will tell us things!

Maybe four of these could be made to work.
https://s.click.aliexpress.com/e/_9jTTRi

[arber333]

I wish these also provided cell voltages though. Balancing is great, but we need BMSs that will tell us things!

I will probably make my diyBMS without balancing. I intend to make 16S boards to fit over the balanser board. It will hold only the sensoric part and comms. This should then report voltages while driving and regulate charger(s).
I will report later with design...

[Alibro]

I was in touch with Tony from Vorteks and he said ANT BMS cannot be cascaded or overlapped but mentioned this
https://s.click.aliexpress.com/e/_AkHH2o
It is similar to the capacitive balancer above but with an app and it can be cascaded.

[MattsAwesomeStuff]

These say they allow "cascading" in the descriptions of those Ali BMSs you showed above, which is daisychaining them to higher series counts.

Even shows pics:



Which makes me wonder...

How difficult would it be to figure out how to daisy chain a power tool BMS?

I.E. I've got hundreds of 5s Dewalt BMS's, I would only need 20 for my build, can they be daisychained? Or is this a "reverse engineer it to find out" kind of answer that's far and above my skillset?

[Alibro]

This is part of the email I got from Tony

"Yes, you can wire the ANT BMS in series as long as they're kept completely isolated from each other. If you overlap them, you're going to end with fire. The downside is, you might have 24 cells at one voltage and another 24 at another voltage etc"

I'm not sure how that relates to Dewalt BMS but probably the same thing.
He also reminded me of a couple of videos he made which I'd forgotten about.

"I did 2 videos which review both balancers.

Part 1
Part 2 "

[arber333]

This is part of the email I got from Tony

"Yes, you can wire the ANT BMS in series as long as they're kept completely isolated from each other. If you overlap them, you're going to end with fire. The downside is, you might have 24 cells at one voltage and another 24 at another voltage etc"

Yes i decided i will not overlap my balansers. Too much spagetti wires. Instead i will top off my modules periodicaly with 63V power supply and balancers will take care of the rest. I dont charge upwards of 4.05V per cell so i will be safe here. In any case i will use my BMS to provide me with cell voltages. I also think of designing CAN bus into master unit so it will provide Chademo controler with temp and voltage signal.

[vwbrady]

I keep coming back to one of these options. That is if my Leaf BMS doesn't work out.

https://www.aliexpress.com/item/1005001 ... w668o&mp=1

http://www.bestechpower.com/communicati ... 170V1.html

[LRBen]

I emailed bestech and they claimed that 80s is too big for their BMS systems. So that rules them out from most car applications.

[vwbrady]

I emailed bestech and they claimed that 80s is too big for their BMS systems. So that rules them out from most car applications.

and that is counter to their website that shows 96s. weird.

[LRBen]

I emailed bestech and they claimed that 80s is too big for their BMS systems. So that rules them out from most car applications.

and that is counter to their website that shows 96s. weird.

I emailed them to confirm this. They said that BMS is obsolete. Shame since it looked pretty good.

[zippy500]