SIMP BMS with BMW Mini Electric battery.

[DFDF]

Hello everyone,

I'm new to the forum and really appreciate anyone's help.

My end goal is to use a mini electric battery in a classic car conversion. I came across SIMP BMS and it seems like a great solution for an open source BMS. I have the battery and the BMS which is loaded with the BMW I3 firmware. Obviously the Mini electric battery firmware is not directly supported, but my logic is that the CSC's are the same so it might be possible.

I have it all set up and I have connected to the batteries "master connector" I defiantly have communication with the battery, it actually seems happy and is reporting as ready to run. However something is wrong. It is showing all 12 CSC modules, with cells 0-11 on each module, but cells 8-11 are showing as 0V on each module with cells 0-7 showing exactly the voltage i would expect at around 3.8v.

Further to this from modules 9-12 every cell is showing as 0v. Only 64 cells are showing in the debug screen and it doesn't seem to matter what I set the cell series to, it only ever shows 64 cells present which is consistent with cells 0-7 on modules 1-8 being present.

The BMW I3 battery is made up from 8 CSC modules with 12 cells in each. Where as the Mini electric is setup also most the reverse with 12 CSC modules and 8 cells per module. I'm thinking this is probably the reason. My thoughts.... which are only thoughts I do not know, are that there are 4 wasted addresses in modules 1-8 as cells 8-12 are not present, when we get to module 9 we are out off addresses so from there on they are 0.

I'm wondering if the fix could be altering some of the code from the BMSModule.cpp, I can see there is a loop looking for 12 values, this might just be the start of the fix.

Can @Tom91 or anyone tell me if I am heading in the right direction or am i going off at a tangent?

Thanks in advance for any help.

[tom91]

You need to expand the code base and add the 4 missing commands for the CMUs. Then you can also clean up to only register/look for 8 cells per CMU.

UpdateJust check my code base, guess you are in luck you just need to set it to MineE CSC spec, in the battery settings menu.

https://github.com/Tom-evnut/BMWI3BMS/b ... .ino#L3329

[DFDF]

That's amazing thanks Tom, this looks like a newer firmware than what the board was shipped with. I will give this a go Tuesday.
Thank you for your help.

[tom91]

board was shipped with

Where did you get your SimpBMS from and when?

[DFDF]

Hi Tom,

No I'm wrong, it shipped with the latest firmware, I did as you said, set the cells to 96 and its all working perfectly.
Thank you again for all your help.

[tom91]

Where did you get your SimpBMS from and when?

[DFDF]

Hi Tom,

Apologies for the late reply, I got it from www.evshop.eu I played the order on 12th March 2025 and received it on 19th March 2025.

[tom91]

Okay, they are not mine and I consider them counterfits.

Got any pictures of them?

[DFDF]

Oh no!!!

Please see the attached.

[tom91]

Yea thats not one of mine.

[DFDF]

That’s ungood. For anyone else reading is the only official place to get one https://citini.com/ ?

I was also wondering, when the BMS is turned on it has an error to do with the number of cells. When I go to the debug screen and send 6 for cell present reset. Everything seems ok. Until the next power down. Then it will start up with the same error until I go back in and reset the cells present.

Is this normal behaviour? The reason I’m asking is I was thinking about only waking the BMS on ignition live or charge present, but how it is right now would make that impossible. I would have to have it connected to permanent 12V.

[tom91]

I was also wondering, when the BMS is turned on it has an error to do with the number of cells. When I go to the debug screen and send 6 for cell present reset. Everything seems ok. Until the next power down. Then it will start up with the same error until I go back in and reset the cells present.

First time I heard of this issue, also been years since I work on the SimpBMS code. Will have to check if there is a parameter for waiting until setting the error. This has to do the wake up of the modules and how quickly they report.

Edit:

It is currently hardcoded to 3 seconds https://github.com/Tom-evnut/BMWI3BMS/b ... C5-L845C48

So this would need tweaking to see if increasing it to lets say 5 works.

[DFDF]

That’s great thanks Tom, I will give that a try and report back.

[DFDF]

Working great! Thanks Tom!