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Posted: **Mon Mar 30, 2026 6:40 pm**

More testing needs to happen and the temperature readings aren't correct.

================ BMW i3 Pack Status: No Faults =============
Modules:2  Pack:95.14V  AvgCell:3.964V  AvgTemp:18.5C  SoC:0%
CellLo:3.878V  CellHi:4.051V  Delta:173mV

Mod #1  46.55V  lo:3.878V hi:3.880V  T:21.0/21.0C
Mod #6  48.58V  lo:4.047V hi:4.051V  T:16.0/16.0C
=====================================================
================ BMW i3 Pack Status: No Faults =============
Modules:2  Pack:95.14V  AvgCell:3.964V  AvgTemp:19.0C  SoC:0%
CellLo:3.879V  CellHi:4.051V  Delta:172mV

Mod #1  46.56V  lo:3.879V hi:3.880V  T:21.0/21.0C
Mod #6  48.58V  lo:4.047V hi:4.051V  T:17.0/17.0C
======================================================

Sure is handy to have something like Claude be able to look at a couple thousand CAN packets and try to decode what's happening. Just can't trust it's code blindly.

https://github.com/hpeyerl/bmw-i3-bms-tcan485

Posted: **Thu Apr 02, 2026 6:11 pm**

Ok. So this is strange.

@gregski sent me his SME and BMW i3 CSC which allegedly came from a 22kwh pack. His CSC is dated 2018 and the SME is dated 2015.

When I snoop the traffic between his SME and his CSC, the packet trace looks basically the same as mine. There are no 0x3D1-0x3D8 frames. (see log dump from SavvyCan).

gregsme.csv: (70.71 KiB) Downloaded 1 time

When I connect Greg's CSC and another one of my CSC's to two different modules, it all operates correctly when set to the 'new' packet variant.

Code: Select all

================ BMW i3 Pack Status: No Faults =============
Modules:2  Pack:95.14V  AvgCell:3.964V  AvgTemp:24.0C  SoC:0%
CellLo:3.878V  CellHi:4.052V  Delta:174mV

Mod #4  48.60V  lo:4.048V hi:4.052V  T:28.0/28.0C
Mod #6  46.55V  lo:3.878V hi:3.880V  T:20.0/20.0C
=====================================================

I'm tempted to conclude that Greg's CSC and SME did not come from an actual BMW i3. Or maybe there are multiple variants of BMW i3 CSC. Or maybe I'm missing something obvious.

Posted: **Tue Apr 21, 2026 1:35 pm**

Wireviz was conceptually interesting but I found it to be pretty high friction for getting my wiring harness designed.

Together with @splicecad, I've been working with the Splice-Cad.com tool and I've found it's far more intuitive and easier to visualize what's happening than WireViz. It's constantly being improved and this is my way forward for sure. Splice-Cad exports JSON and even has a way to push revisions directly to my Github repo and kick off a GitHub action to render my schematic/layout.

Example: https://github.com/hpeyerl/evj55/blob/m ... ematic.pdf

Anyone doing an EV conversion, could conceivably download my JSON https://github.com/hpeyerl/evj55/blob/m ... _plan.json and import it to their own Splice-Cad project, or simple copy/paste the portions of it they want.

Posted: **Thu Apr 23, 2026 5:01 pm**

Got 8 batteries across two packs in the truck. The first time I've spoken to the modules and definitely the first time since I manually charged each module.

BMS running on a Lilygo T-CAN485 using the code at https://github.com/hpeyerl/bmw-i3-bms-tcan485

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