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BTW, I have 23 BMS boards, believed to be operational, with an undetermined number of unique IDs.
 

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retepsnikrep said:
It' easy to discover which ID is which block during bench testing.
Plug them into a CAN monitor one at a time, see what ID pops up and write that on the block in marker pen!
jime said:
The essential task would be to have each owner have a simple and inexpensive set of HW/SW to read the ID. That in place, we could all swap boards until everyone is happy.
BTW, I have 23 BMS boards, believed to be operational, with an undetermined number of unique IDs.
If need be .. we could make an event at next Insightfest .. people bring their boards .. and we plug them into CAN-USB laptop , identify the CAN IDs for each board .. and if there is a conflict shuffle / swap to make non-conflict sets .. or outside of gatherings we could do the same thing , just with added shipping cost (the boards alone, are not very expensive to ship.)

retepsnikrep said:
So it seems to be simply a matter of using a spare output on the BCM Replacer to control a 4053 2/3 way DPDT switch chip or similar.
My hunch .. is that we will not end up having to result to such switching .. but .. 'worst case' that should also work.
 

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If need be .. we could make an event at next Insightfest .. people bring their boards .. and we plug them into CAN-USB laptop , identify the CAN IDs for each board .. and if there is a conflict shuffle / swap to make non-conflict sets .. or outside of gatherings we could do the same thing , just with added shipping cost (the boards alone, are not very expensive to ship.)
Now there's a good idea - seems to me. Would avoid a bunch of folks having to try to set up unfamiliar equipment, and the cost of it:)
 

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Well, I went back and watched the original post. Turns out Peter was already ahead of us all on the "swap" club.

Old brain cells just forgot.
 

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If I were doing it, I'd have a dedicated CAN controller for every battery, so they're all on separate buses. No conflicts then, no matter which addresses each board has.
The standard setup is only 3/4 batteries, so not like it'd be too overly complex.
 

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So I've been looking at getting a pair of these LTO from Greentec, and found this thread and am glad to see it seems the circuit board on top does appear to be a BMS. If I don't care much about getting the information via the CANBUS, but do want the charge/discharge/balancing functionality, is there anything in particular I'd need to do other than use appropriate sized wiring for the main power terminals? Based on EndlessSphere link earlier in the thread, it seems that I need to supply power via the CANBUS connectors to the BMS boards in order to handle the charge/balancing?
 

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So I've been looking at getting a pair of these LTO from Greentec, and found this thread and am glad to see it seems the circuit board on top does appear to be a BMS. If I don't care much about getting the information via the CANBUS, but do want the charge/discharge/balancing functionality, is there anything in particular I'd need to do other than use appropriate sized wiring for the main power terminals? Based on EndlessSphere link earlier in the thread, it seems that I need to supply power via the CANBUS connectors to the BMS boards in order to handle the charge/balancing?
As far as the OEM BMS boards from Honda on the LTO modules .. As far as I know :

#1> Balancing is not automatic .. it must be commanded to do the balancing .. via sending the unit some (yet unknown) CAN message.

#2> So far using them as cell level voltage monitoring is as far as has been deciphered.

#3> Alternatively .. there are numerous other cell level balancing options out there .. just be careful the one you choose will do the LTO voltage range.

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As for what else you need .. you will need .. something that monitors those cell level voltages ... and then takes action based on those voltages .. actions like .. Disable Charging when full .. Disable Discharging when empty .. take action to notify and protect when/if cells fail or get significantly out of balance .. and of course installing / mounting / connecting the cells-modules themselves.
 

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As far as the OEM BMS boards from Honda on the LTO modules .. As far as I know :

#1> Balancing is not automatic .. it must be commanded to do the balancing .. via sending the unit some (yet unknown) CAN message.

#2> So far using them as cell level voltage monitoring is as far as has been deciphered.

#3> Alternatively .. there are numerous other cell level balancing options out there .. just be careful the one you choose will do the LTO voltage range.

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As for what else you need .. you will need .. something that monitors those cell level voltages ... and then takes action based on those voltages .. actions like .. Disable Charging when full .. Disable Discharging when empty .. take action to notify and protect when/if cells fail or get significantly out of balance .. and of course installing / mounting / connecting the cells-modules themselves.
Ah, I see, thank you. So folks have done some hard work, but only part-way there. If I really want a 'plug and play' type solution, I'd need a separate BMS that handles LTO cells, and then I can get simple "put the voltage in/out leads here".

Thanks!
 

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Pretty much the case. The LTO solution is pretty simple for the initial manual capability. If one wants a fully capable BMS, then you would need to add a BMS such as the Orion.

It all boils down to what is good enough. Many experimenters think the LTO packs themselves are good enough because they are quire stable and maintain balance quite well. An occasional manual rebalance might be needed.

A step more "managed" is to use the top balancing chips which retepsnikrep has recommended. They balance on charge, so they do a pretty good job with LTO.

If you want active minute to minute balance, then something like the Orion is needed.

Non of this is drop in, nor will it ever be. You have to be an experimenter at heart, but many such folks are making it work:)
 

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Discussion Starter #50
Pretty much the case. The LTO solution is pretty simple for the initial manual capability. If one wants a fully capable BMS, then you would need to add a BMS such as the Orion.

It all boils down to what is good enough. Many experimenters think the LTO packs themselves are good enough because they are quire stable and maintain balance quite well. An occasional manual rebalance might be needed.

A step more "managed" is to use the top balancing chips which retepsnikrep has recommended. They balance on charge, so they do a pretty good joy with LTO.

If you want active minute to minute balance, then something like the Orion is needed.

Non of this is drop in, nor will it ever be. You have to be an experimenter at heart, but many such folks are making it work:)
I think the above sums it up well. These LTO packs seem quite stable, even for people with no BMS.

We can now read the cell voltages from the onboard OEM BMS so can prevent cell over or under voltage scenarios by monitoring them and then controlling IMA assist/regen functionality.

IMHO minute to minute balancing is not required unless,
you are determined to get the last 0.1% out of an exhausted pack or into a fully charged one.

Top balancing during charging can be done with the simple bypass devices I proposed in the other thread.
We can monitor the effectiveness of that with our cell voltage readings.

Of course if you want it all combined and automated you will have to add an Orion2 or equivalent.
 

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I have a question I am hoping someone might help answer. I am using Honda Fit batteries in two different solar battery bank systems. One is a 48V and the other is 24V. I am wondering what someone is using to enable individual cell readings of charge. So far, I have learned that a BMS system doesn't seem to work on LTO batteries like they perform in Lipro4 to keep the cells balanced. I want to be able to have a reading, if possible, to apprise myself in the event a cell isn't keeping a proper balance of other cells in the battery modules. Hopefully, something is available for all 24 cells in each pack. On the 24V system, because I am paralleling each 12 cells, something in a 12 cell composition will work. I don't know how marrying the two 12 cell packs in series for a 48V battery will work. I want to run the 48V batteries at 60V nominal and 46V minimal however I intend to run the 24V at 30V nominal and 22.4V minimal due to the overall system setup.
Anything anyone can add will be greatly appreciated.
 

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Discussion Starter #52
I suggest you read up on all my LTO CAN BMS Research.
Watch a few videos from my YT channel then contact me..
I have a voltage reading device available for them..

 

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Thank you. I will bare my ignorance and ask you what the name of your YouTube channel is and, because I am new to this forum, how to navigate to find your written information. Electrical terminology is something I am having difficulty grasping so, I beg you to bear with me for asking questions that sound absolutely ridiculous to you. I have been one who can immediately imprint knowledge working hands on beside someone instructing me but, have difficulty grasping things in this area not knowing how certain functions are applied through reading. If it was possible, when viewing videos, to ask questions when one doesn't immediately understand something they see being done on a video, it would be most helpful. I have watched videos repeatedly when one small element is assumed by the presenter that skews the ability of the viewer to duplicate what is being presented.
You certainly have excellent knowledge of everything in this field and I only mentioned that you might have awareness of viewers who have none that are using you as a mentor for knowledge from your presentations.
Again, I graciously thank you for responding to my dilemma and will look forward to learning from you.
 

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Discussion Starter #54
 

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Thank you. I will bare my ignorance and ask you what the name of your YouTube channel is and, because I am new to this forum, how to navigate to find your written information. Electrical terminology is something I am having difficulty grasping so, I beg you to bear with me for asking questions that sound absolutely ridiculous to you. I have been one who can immediately imprint knowledge working hands on beside someone instructing me but, have difficulty grasping things in this area not knowing how certain functions are applied through reading. If it was possible, when viewing videos, to ask questions when one doesn't immediately understand something they see being done on a video, it would be most helpful. I have watched videos repeatedly when one small element is assumed by the presenter that skews the ability of the viewer to duplicate what is being presented.
You certainly have excellent knowledge of everything in this field and I only mentioned that you might have awareness of viewers who have none that are using you as a mentor for knowledge from your presentations.
Again, I graciously thank you for responding to my dilemma and will look forward to learning from you.
Most BMS's in the solar industry are built around other chemistry batteries. The reason they don't balance is most do their balancing near the top of the voltage curve and for liion or lifepo4 that is higher than LTO. The top for LTO is 2.7V and thus never hits a voltage where those BMS's start to balance (which for those types is usually around 3.6V). If you search for it you can find LTO specific BMS's for solar but the easiest route is probably to use a programmable BMS (sometimes called a "smart" bms that runs Ant BMS software). In those you set the high and low voltage cutoffs on your phone and also set at what voltage you want it to start balancing.

In an automotive setting there are different needs but for solar buying one is probably easiest.
 

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Discussion Starter #56
We know the LTO BMS has to have the cell balance function enabled via a CAN command to operate.
Now we could send it to the BMS if we knew what it was.

This info from some Toshiba documents is interesting.

(2) Cell voltage balancing
CMU receives the balance signal “1:Enable” from the BMU and it starts the balance circuit.
It starts the cell balance (discharge) control to a target voltage (typically:10 mV).
During voltage measurement, the CMU stops balancer temporarily in order not to affect the
measurements.
If the target voltage is higher than all of the cell voltages in the system at that time, or if
there are cell voltages higher than 2.8V, or if there are cell voltages lower than 2.1V, then the
balance feature does not work.
(3) CAN communication features
CAN communication I/F and BMU specifications are as follows.Data, such as control
instructions from the BMU, temperature and voltage, and module status are transmitted via
CAN communication. For structures of the data frame and definitions of the send/receive
frame, please refer to“Stationary Battery Module BMU development guide (6E6V0058)”.
It looks like we need document mentioned above.. ;)

Any ideas? Google draws a blank.
I registered on the Toshiba site but it's not on there. :(

Anyone with a posh e-mail address, some clout and fat cheque book want to ask for it?? :oops:
 

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Seems like there are only BMU development documents for their Type 3 modules available to download to the public (attached). Any chance they might be using similar CAN commands in the FIT modules or this for something completely different?
 

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Discussion Starter #58 (Edited)
Thanks. Asfaik they outline the data exchange between the BMU (Battery Management unit) which is the BMS master module, and the Host computer. i.e. The car main CPU or whatever.

We need details of the exchanges between the BMU and the CMU (Cell Management Unit) BMS boards.

Sadly they don't help unless I have missed something apart from general layout/process etc.
 

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Discussion Starter #60
I have all the available docs from the Toshiba site.
No leads that I can see apart from the name of the document we need as mentioned earlier.

“Stationary Battery Module BMU development guide (6E6V0058)”
 
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