openinverter forum

2nd balance board...

hanskraayeveld wrote: ↑Tue Oct 07, 2025 4:48 pm Trace M3 balance board.rar

Its original a *.sal file, but I could not upload it, so zipped it

I have reviewed the SPI comms, there seems to be no data coming back from the BMB. The batman on the BMS board seems to be sending some info, or atleast responding to SPI commands. Yet when looking to read data from a BMB nothing is passed on.

Can you please remove IC4 from the board. MAX17841. That should solve the problem.

Excellent!

hanskraayeveld wrote: ↑Fri Oct 10, 2025 5:20 pm

So removing the MAX chip that is also on the SPI bus solved it. Good to note this for this hardware version.

I only even worked on M3 on older version and now ONLY the MAX on the new version.

I also connect 4 modules, changed parameters to 4 modules, plugged two wires in one connector on hvc, other connected to hvc, but little data?
After it, I plugged out other connector from bmb4 to hvc, but same data.

After it connect to one module again, same... little data.

Is it unstable?

Data is very unstable...

Now its not displaying voltages anymore... somethimes some temperatures

After a night, cell voltages are back ...
Sometimes temps comes and then go...
I select balancing on, first time showing 23 balancing, now none...

What could be the problem?

Other board is working fine... So I have one board which was working good, now not.
One board is working on one module. I am afraid to test it on 4 modules, maybe I ruïned the other also

So next for me to do is a small modification on balancing.
I want to change this line:

umin to umax
+ BalHys to - BalHys

I want to balance from top to bottom. So first bleed the highest...

I can change in code really simplex, but the question is: how to upload

No experience with it. I can save file, but normally I work with arduino or teensy.

I think I have to convert all (included) files to a bin file, and then upload it.

Could anybody help?

hanskraayeveld wrote: ↑Sun Oct 12, 2025 4:19 pm Now they are working, and know what the problem is

Please explain what you changed to now get the data working again?

The M3BMS software is written based off of Open Inverter libraries and bootloaders. The same as the STM32_VCU aka Zombieverter. Others and I create more info on how to build the code in the readme for the Zombieverter code base: https://github.com/damienmaguire/Stm32- ... IBUTING.md

tom91 wrote: ↑Sun Oct 12, 2025 4:26 pm Please explain what you changed to now get the data working again?

1 is good working, other is not working good, somethimes, I'll replace batman chip, I think resistance is too low faom some legs to eachother

What happened if I connect a 108 bricks LFP battery?

Do you have info on the BMBs used? Never been done before so could need some tweaks.

Did a update to both boards....

With STM programmer. What a hell of a job... Without Tom, never succeed...

I replace very little:
Balance voltage is highest cell voltage - balhyst (0.002v)

Hopefully it will balance nice....
7 mv imbalance

8 cells balancing

Possibly is not fully working, I had it working on my bench on 18650s with a 24s BMB, I now also have 23s and 25s BMBs to look at on the bench.

I have now a Standard Range battery, so 4x 24 cells.
Next Ill try a Long Range, 2x 25 2x 23 cells.
After it an LFP 108 bricks.

http://portal.greenaid.nl/TBC%2024015
Tesla Model 3 SR battery as home battery, still balancing now with Damian/Tom tool
http://portal.greenaid.nl/TBC%2024000
Tesla model S battery also as home battery, connected to Tesla M3 battery, still working

http://portal.greenaid.nl/TMC%2025004
This is a Tesla model S battery balancer. (Based on Toms simpbms) Only better

After a night, seems cell balancing does not do anything (spectacular) (Can be my fault)

Question for makers: cell balancing M3 module is done by resistance wire, right?

1: How did you imitate this on a bench?
2: When balancing, cell voltage is not available (shorting wires), how is voltage measurement performed when balancing? Balancing stops for a few ms?
3. Why is uavg not matching, also before I do modulifications

I think he is doing something. But what?
5mv imbalance
52 cells balancing
It seems the lowest is more rising in state of the highest are decreasing...

hanskraayeveld wrote: ↑Tue Oct 14, 2025 5:47 am Question for makers: cell balancing M3 module is done by resistance wire, right?

1: How did you imitate this on a bench?
2: When balancing, cell voltage is not available (shorting wires), how is voltage measurement performed when balancing? Balancing stops for a few ms?
3. Why is uavg not matching, also before I do modulifications

1. request balancing and check feedback from the BMBs, as I said I will look to find some time soon to revisit this.
2. Before requesting a measurement balancing is paused. This maybe the reason balancing is not happening porpperly.
3. No idea can take a look when having everything set up again.

I measured the amps (with a very percisely meter) and I measure its balancing.

I measured parallel the brick wire. The last and first brick wire current is flowing one way.
The middlest brick wires, current is flowing forward, a sec, and back a sec.
So it is bleeding, for sure...
So it seems it cannot bleed all bricks the same time.

Am I right?

I hear also something clicking on bmb every 2/3 sec

4mv imbalance
89 balancing
After 29 hours working time

Works nice for me, as expected, only little speed up
I measured balancing/bleeding time is approx. 25%
Hopefully Tom can speed it up to 95%. 5% for measuring voltage.
He also did that for model S.

Tom is working on it... So fingers crossed

Cells balancing 95


I stopped balancing today, this is can readout.
If I had more time balancing would be perfect balanced within 1mv