Smart BMS

[Jeff Earl]

On 6/23/2019 at 6:18 PM, Chriull said:

Stupid arguing of Kingsong - they should change their responsible engineer.

Only because ninebot messed it up, there is no reason against a better BMS. Would be great to have a wheel to show the real battery state (cell voltages) - that could warn once cells get unbalanced and aged. 

The 16X spec sheet on the Kingsong website clearly describes a BMS capability: "Smart BMS with balance, over charge, over current and short-circuit protection". I'm hopeful that this makes it into the production version.  I feel it's an important safety feature as long as it's engineered and implemented  properly.  Perhaps @US69 or @Jason McNeil can validate if a real BMS is expected to be included in the final package (along with angled footplates, CST tire, 12 MOSFETs, etc. )

[Chriull]

50 minutes ago, Jeff Earl said:

The 16X spec sheet on the Kingsong website clearly describes a BMS capability: "Smart BMS with balance, over charge, over current and short-circuit protection". I'm hopeful that this makes it into the production version.

That's the normal standard, as they used it with all wheels.

From the description it's "missing" cell undervoltage and "cell voltage difference" monitoring.

[US69]

2 hours ago, Jeff Earl said:

The 16X spec sheet on the Kingsong website clearly describes a BMS capability: "Smart BMS with balance, over charge, over current and short-circuit protection". I'm hopeful that this makes it into the production version.  I feel it's an important safety feature as long as it's engineered and implemented  properly.  Perhaps @US69 or @Jason McNeil can validate if a real BMS is expected to be included in the final package (along with angled footplates, CST tire, 12 MOSFETs, etc. )

Sure there is a balancing BMS -with all mentioned protections - in the 16X, like in all KS wheels. These BMS are specially made for the designed Batterypacks.

What ecodrift wants, and what @Chriull is talking about is a „smart BMS“ which shows the value of each cell over the app.

That is something, that in the moment no EUC really has. There are Smart BMS on the market, which contact to a app provided by the producer of the Smart Bms. amd then you can show the values in this special app.

What Chriull and other forget...first of all these Smart BMS are mostly only available in a special size. So KS would need to produce one on their one. Also, if you will NOT like to have the cell values shown on a special app...you would need to install a communication between BMS and board...so that the KS app can show the values. That is all not that easy as some have it in their mind or think!

 

Just now in the moment i have a „custom 18S“ for me in production at 1radwerkstatt.

This will be a stabdard 680wh 18S...which will receive a 840wh custom battery pack on Top WITH smart BMS!

(1520wh in total)

There are several potholes to avoid on installation. Just alone the fact that there are 3 packs in the wheel will make it difficlut to use the Smart BMS „as it is“....The size of the Smart BMS is huge and nearly hasnt fit....Then -for reading the values correctly- we had to decide if we go over the KS board protection fuses. And leave all safety to the Smart BMS alone. We are working on this custom/smart BMS wheel for over 6 weeks now....and i hope next week i can finally show it here (then more on the problems and potholes)

 

What i want to say: You can not „JUST USE“ a Smart Bms from a third party producer and it will work easy peasy. Just alone that you have 2 packs makes it difficult. And for correct integration  or even producing it yourself, you need todo several changes on hardware which need time AND cost money.

 

Edited July 6, 2019 by US69

[esaj]

But doesn't KS already produce their own BMS's, along with everything else (electronics-wise)?

Prior to self balancing scooters business, King song has been engaged in developing and producing power bank protection board, all of the control boards of king song scooters are made by our own SMT factory, which is one of our advantage compared to our competitors, we can be more flexible and gurrantee quality of core components.

 

Also, doesn't Ninebot Z-series show the individual cell voltages in the app?

 

 

Edited July 6, 2019 by esaj

[US69]

23 minutes ago, esaj said:

But doesn't KS already produce their own BMS's, along with everything else (electronics-wise)?

Yes, they do...they do Boards and BMS themself!

But as said...to have a smart BMS involved with app, you need to have communication between BMS and Board, that is nothing easily done as it needs several hatdware changes, also on the Board.

BUT: Afaik they are working on something similiar allready . I have allready seen boards with a 32pins or more „battery connection“...

But didnt get into production. As said...quite some effort and money and development.

[US69]

33 minutes ago, esaj said:

Also, doesn't Ninebot Z-series show the individual cell voltages in the app?

Dont nail me on this: afaik no...there is another app, which can show the cells...

But it is questionable what this other app does...as there are 14s6p...and this app just shows 14 values...

Then also, the 9b z10 has 2 times 14s3p...and to my knowledge they are not really connected...as their voltage can run different And DOES run different, especially when you re-generate energy by braking, all the energy only goes into one of those packs. so to call the z10 BMS smart is quite a overstatement....

It is very good in emptying the Z10 :-)

 

Edited July 6, 2019 by US69

[Jeff Earl]

Wow. Didn't know I was opening such a can of worms. Thanks for sharing the wealth of knowledge on the topic, everyone. I feel better knowing that the basic BMS safeguards are standard fare for all Kingsong wheels. While it would be great to have a comprehensive, genius-level SmartBMS; at the end of the day, I'm most concerned with safety and robustness. If wiring dozens of sense wires and communication buses across multiple packs increases complexity and the opportunity for failure, I can probably sleep well without knowing the voltage on each individual cell.  But it would be cool...

[Planemo]

1 hour ago, US69 said:

But it is questionable what this other app does...as there are 14s6p...and this app just shows 14 values...

Then also, the 9b z10 has 2 times 14s3p...and to my knowledge they are not really connected...as their voltage can run different And DOES run different, especially when you re-generate energy by braking, all the energy only goes into one of those packs. so to call the z10 BMS smart is quite a overstatement....

It is very good in emptying the Z10 :-)

 

Very true. The Z10 uses 2x 14s3P so I can only assume that the ninebattery app provides the average for 3 cells which clearly isn't ideal and certainly isn't voltages for individual cells.

Of course, that isn't to say that the wheel itself doesn't actually monitor individual cells, only that the app cant cater for it. It may also then be the case that Ninebot engineers can indeed access individual voltages with the equipment they have.

So until we know exactly what the Z10 BMS can and does do, it's impossible to say what it's actually monitoring. It may monitor individual cells, it may not.

As regards to the regen on one pack only, I can't believe that Ninebot 'didn't notice' this and must have done it for a reason. The sceptic in me suspects that the wheel was initially designed to be compatible with either one pack (as per the Z6/Z8) or the 2 packs of the Z10. And so when they used the 2 packs for the Z10 they didn't change the hardware and therefore shoved regen through only one pack as per the Z6/Z8. I am fairly confident that the boards and wiring are identical for all models which would support this suspicion. For sure, the Z6 has a spare XT60 battery connector hanging off it, ready for the 2nd pack. I have also looked pretty closely at the power/mother boards for Z6/Z10 and they look identical.

Of course this doesn't make regen through 1 pack on the Z10 right, only that I think they know why they did it. Surprising really considering the design and efforts gone into making the wheel.

[Chriull]

9 hours ago, US69 said:

What ecodrift wants, and what @Chriull is talking about is a „smart BMS“ which shows the value of each cell over the app.

That is something, that in the moment no EUC really has.

The ninebot z10s have it - they just messed up the communication with the mainboard, so they drain senslessly battery once the system should be shut down...:(

9 hours ago, US69 said:

There are Smart BMS on the market, which contact to a app provided by the producer of the Smart Bms. amd then you can show the values in this special app.

What Chriull and other forget...first of all these Smart BMS are mostly only available in a special size. So KS would need to produce one on their one. Also, if you will NOT like to have the cell values shown on a special app...you would need to install a communication between BMS and board...so that the KS app can show the values. That is all not that easy as some have it in their mind or think!

...

Just alone the fact that there are 3 packs in the wheel will make it difficlut to use the Smart BMS „as it is“....The size of the Smart BMS is huge and nearly hasnt fit

No. Such a smart BMS can easily be fit in the size normal standard BMS have by now. The PCB have the size Of the whole battery pack - more than enough to put some "supercomputer" on it nowadays...

9 hours ago, US69 said:

What i want to say: You can not „JUST USE“ a Smart Bms from a third party producer and it will work easy peasy. Just alone that you have 2 packs makes it difficult. And for correct integration  or even producing it yourself, you need todo several changes on hardware which need time AND cost money.

Yes. ?texas instruments? for example imo has such an IC which handles all the measurements and communications. Is nothing cheap - but all the new wheels are neither!

 So this extra should be included! Just to give us customers the possibility to replace unsafe/aged battery packs - this would be also a future investment for the manufacturers to stay in the western market! Every accident with the li ion cells could lead to an immediate ban...

Here are more than enough reports of 0V cells in battery packs - one has to cut  open the packs to verify this!

And not cutting of with cell undervoltage was a "great" step in EUC history to prevent BMS cutouts in the early days, but by now showing absolutely _no_ warning is irresponsible.

This has nothing to do especially with Kingsong - this concerns all EUC manufacturers.

Like not implementing "dynamic" tiltbacks or overlean warnings in firmware is showing lack of willingness for improvement from the manufacturers. Just making stronger and bigger wheels has an expiry date.

Making better, safer and more reliable wheels with the new generation performance should imho bring a great advantage on this "small" market.

Just my humble opinion....

[US69]

21 hours ago, Chriull said:

The ninebot z10s have it - they just messed up the communication with the mainboard, so they drain senslessly battery once the system should be shut down...:(

No. Such a smart BMS can easily be fit in the size normal standard BMS have by now. The PCB have the size Of the whole battery pack - more than enough to put some "supercomputer" on it nowadays...

Yes. ?texas instruments? for example imo has such an IC which handles all the measurements and communications. Is nothing cheap - but all the new wheels are neither!

 So this extra should be included! Just to give us customers the possibility to replace unsafe/aged battery packs - this would be also a future investment for the manufacturers to stay in the western market! Every accident with the li ion cells could lead to an immediate ban...

Here are more than enough reports of 0V cells in battery packs - one has to cut  open the packs to verify this!

And not cutting of with cell undervoltage was a "great" step in EUC history to prevent BMS cutouts in the early days, but by now showing absolutely _no_ warning is irresponsible.

This has nothing to do especially with Kingsong - this concerns all EUC manufacturers.

Like not implementing "dynamic" tiltbacks or overlean warnings in firmware is showing lack of willingness for improvement from the manufacturers. Just making stronger and bigger wheels has an expiry date.

Making better, safer and more reliable wheels with the new generation performance should imho bring a great advantage on this "small" market.

Just my humble opinion....

As i have said in my previous answer...

As long as you have more than ONE battery alone....and like on our EUCs 2 or more battery packs it is NOT that easy to install Smart BMSs. As said 1radwerkstatt is just trying that on my custom 18S and there are several hurdles to overcome. 

It would be a easy thing if we would have just one pack in our wheels....but as soon you have them split up because of the room...its a mess.

[Chriull]

7 hours ago, US69 said:

As i have said in my previous answer...

As long as you have more than ONE battery alone....and like on our EUCs 2 or more battery packs it is NOT that easy to install Smart BMSs.

Yes - it'll take a whole new design, no real ready to use, cheap 3rd party solutions ready? EUCs evolved nicely over time - i am most propably to impatient...

7 hours ago, US69 said:

As said 1radwerkstatt is just trying that on my custom 18S and there are several hurdles to overcome. 

It would be a easy thing if we would have just one pack in our wheels....but as soon you have them split up because of the room...its a mess.

Looking forward to see your found solution once it ready! Could give some "push" to Kingsong once you have it?

On 7/6/2019 at 7:15 PM, Planemo said:

Very true. The Z10 uses 2x 14s3P so I can only assume that the ninebattery app provides the average for 3 cells which clearly isn't ideal and certainly isn't voltages for individual cells.

This 3 cells are in parallel - so there is no average to be shown, they have the same voltage by beeing paralleled. And the different voltages for both packs are shown seperately.

But from what i got, they messed up (at least) two points:

- once the wheel/mainboard is shut off the communication line from the BMS still drains too much power ( vampire drain). Here in the forum one member posted a diy solution on how to cut this (sorry - did not find the link...)

- while driving the packs can get at different voltage (charge) states. Afaik from regenerative braking. If one shut down the wheel in such a state one cannot turn it on again...

So maybe one should not put too much "pressure" on ks (and other manufacturers) to implement such a system soon, as this needs a well thought design..

But they could as first step start with "just" a monitoring system which warns the user once some cells have too low voltage, without "any restrictive" actions taken by the firmware?

[Planemo]

4 hours ago, Chriull said:

This 3 cells are in parallel - so there is no average to be shown, they have the same voltage by beeing paralleled. And the different voltages for both packs are shown seperately.

But from what i got, they messed up (at least) two points:

- once the wheel/mainboard is shut off the communication line from the BMS still drains too much power ( vampire drain). Here in the forum one member posted a diy solution on how to cut this (sorry - did not find the link...)

- while driving the packs can get at different voltage (charge) states. Afaik from regenerative braking. If one shut down the wheel in such a state one cannot turn it on again...

Yes I get that re the 3 cells in parallel, but my point was that you could quite easily have 2 cells propping up a duff 3rd cell and not know about it, or at the very least, not know which one of the 3 is actually duff without testing all once dissassembled. The only true 'smart' bms IMO is one which monitors each individual cell.

I am aware the app shows voltages for each pack. I was trying to direct attention to cells not packs.

Re vampire drain I agree. Its not right. I have however looked into carrying out the mod and decided against it purely because I will never be away from my wheel long enough to worry about it.

Re regen, I also agree that its not right as I stated before. I only put foward my suspicion as to why it has been designed that way. Again though, it doesnt bother me as I dont have enough hills to worry about the packs getting horrendously unbalanced betwen rides. Nor do I run my packs very low.

[Chriull]

5 minutes ago, Planemo said:

Yes I get that re the 3 cells in parallel, but my point was that you could quite easily have 2 cells propping up a duff 3rd cell and not know about it, or at the very least, not know which one of the 3 is actually duff without testing all once dissassembled. The only true 'smart' bms IMO is one which monitors each individual cell.

Since they 3 cells are in parallel they'll die together. At least once the first "duff" cells pulls the others below ~2-2.5V.

Maybe one could rescue the other two if one notices the situation early enough?

[ir_fuel]

10 minutes ago, Planemo said:

Yes I get that re the 3 cells in parallel, but my point was that you could quite easily have 2 cells propping up a duff 3rd cell and not know about it, or at the very least, not know which one of the 3 is actually duff without testing all once dissassembled. The only true 'smart' bms IMO is one which monitors each individual cell.

 

The question is: why?

If you see that your group of 3 cells has abnormal values, are you going to open your euc, open the battery pack, and replace the faulty cells? Let's say you do instead of replacing the entire battery pack. First you need to know what group of 3 cells in the battery pack it concerns, and once you know that you can test those cells individually, once you disassembled them, no?

TBH I think for most people knowing that "something" in the cells of the pack is wrong is more than enough info. They can then either:

- go to a shop and have them fix it

- if they are a bit more DIY buy an entire pack and swap it out

- if they are even more DIY, open the pack and figure out what cells to replace and install it again.

 

If one of your cells in a 3-cell config is dead, you'll never get a 4.2V reading on that group anyway.

[Planemo]

My point is that if you are going to use a bms to monitor, why not monitor each cell? Or the other way, why stop at monitoring 3? Stuff it, how about 4 or 5? 10? It seems to me that the best solution is to monitor all.

Dont get me wrong, its nice to be able to nail down any duff cell/s to blocks of 3 for the reasons you state (and I would replace all 3 myself) but being able to monitor individual cells would be better and lead to quicker diagnosis. Lets not forget that the bms will continue to try and overcharge what could be 2 perfectly good cells if the 3rd isnt taking a charge properly and bringing down the overall voltage. You will soon kill all 3 cells rather than just focusing on the duff one. I appreciate that the cost of 3 cells as opposed to one isnt really an issue, its more the quick identification of a single cell and its quick replacement which could prevent serious issues rather than having a slow deterioration in one cell which gradually take down two others and before you know it you have 3 duff cells which could potentially be more of a fire/catastrophic risk than the early replacement of a single cell. Maybe I am just being too pedantic but surely if you are going to drill it down to packs of 3, you may as well go the whole hog and drill it down to 1.

[Tadas]

The main benefit of a smart BMS would be to give the user a warning about a defective battery pack. Currently, no such warning exists for Gotway and Kingsong wheels.

Monitoring all voltages via a smart BMS would have helped me a lot and it is my first wheel! I imagine it would be even more important for aging battery packs.

[ir_fuel]

3 minutes ago, Planemo said:

but being able to monitor individual cells would be better and lead to quicker diagnosis

That's where we disagree on.

Also, about your "why": I guess it's a lot easier to measure parallel cells at the connection point of each parallel connection, than it is to wire each individual cell to a BMS for monitoring.

 

[ir_fuel]

But we can agree on one thing: adding hardware that can detect failures is always a good thing. It's not as if you can easily measure and swap out batteries as you can do on a drone. 

[Chriull]

10 minutes ago, Planemo said:

My point is that if you are going to use a bms to monitor, why not monitor each cell? Or the other way, why stop at monitoring 3? Stuff it, how about 4 or 5? 10? It seems to me that the best solution is to monitor all.

This is for battery pack configuration like the 20s3p - meaning always 3 cells in parallel and 20 of these blocks in series. All the packs of 3 cells in parallel have to have the same voltage - they are fix connected. So if one measures the voltage of one, its exactly the same voltage as the other 2...

So for example for such a 20s3p pack one needs to monitor the 20 packs of 3 parallel cells - measure 20 voltages. By this one knows the voltage of all 60 cells.

[meepmeepmayer]

Not sure exactly what you argue about here, but I'm with @Planemo. Of course it would be nice to monitor every individual cell, so you see if there are tiny differences that might develop into something bigger.

(Also I split this into its own thread)

[Planemo]

I get the parallel thing. I am just unclear why they are not able to isolate each cell purely for the purposes of monitoring (some sort of gate/diode?) prior to being made up into whatever P is required.

I cant help feeling that stating one knows the voltages of 60 cells from only 20 readings is a bit of a misnomer.

 

Sorry meep I just replied to Chriull, must have gone through just prior to you splitting the thread.

[andress]

You say that you want to monitor each individual cell, but what exactly do you want to monitor? Voltage? Than it will always be same for all the cells in paralel (3 in case of Z10) and it is physically impossible to measure any difference since their leads are connected. You could however monitor temperature of each individual cell. This would most likely give you some information about the health of the cell but the price for so many sensors is much more than the information is worth.

[Planemo]

1 hour ago, ir_fuel said:

That's where we disagree on.

I cant for the life of me think why one would feel it preferable to restrict ones diagnostic abilities.

I come from a dignostic background so the more information I have got the quicker it is to deal with. Additionally in this case, any delays in replacing a cell will only add to the risk.

[ir_fuel]

Just now, Planemo said:

I cant for the life of me think why one would feel it preferable to restrict ones diagnostic abilities.

If you have 3 cells in parallel and one dies, you'll know it because the average will never be 4.2V again over those 3 cells. The only thing you won't know is which of the 3 cells has died.

We're not talking 0.1V differences here. 

Unless there is some way in which 3 parallel cells still can push out 4.2V with one cell being dead of course.

[Planemo]

4 minutes ago, andress said:

You say that you want to monitor each individual cell, but what exactly do you want to monitor? Voltage? Than it will always be same for all the cells in paralel (3 in case of Z10) and it is physically impossible to measure any difference

I did reply to this scenario in the other thread before they got split. I am surprised we dont have the technology to isolate cells for bms purposes prior to being hooked up into whatever P.