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VCU as a BMS main on the CAN bus

Posted: Thu Apr 10, 2025 11:27 am
by TommyB
Hello everyone,

in the Johannes VW touran update he started using MEB battery platform modules in his conversion and from what I gathered from the video and on the wiki, he is directly using the VCU as the master BMS to use with the BMS slaves that come with each module.

Now my situation is similar as in my conversion I will be using MEB modules (got the whole ID4 battery pack 82kw for dirt cheap).

Now before buying a bunch of parts, i have questions:
1. The obvious question is what are the downsides to this route of implementation? From what I gather there might be that ID can clash if there are more devices on the network, but Johannes has a bunch of stuff and it seems to work fine for him.

2. If I go this route the idea would be to try to implement this into Zombie, unless I missed something and there is this option already and that probably answers all my questions. It has SimpBMS support, but from what i understands it for "high level" CAN commands not BMS slave management.

3. Plan B which is probably plan A, get the same-ish setup as Johannes is using and start hacking away for stuff i need.

Any suggestions, solutions, ideas or already WIP things that can help are very welcome.

Re: VCU as a BMS main on the CAN bus

Posted: Thu Apr 10, 2025 12:47 pm
by johu
Attached is a CAN log of all 9 modules connected to CAN bus. There you can check for ID clashes.
I didn't get any, maybe because VW maintain a table of all IDs they ever used?

Even the small BMS that only monitors one module sends out messages for 4 modules. So it's like 12 modules.

The code of mebbms.cpp could also be ported to Zombie. It generates the high level values

https://github.com/jsphuebner/stm32-car/tree/touran-meb

Re: VCU as a BMS main on the CAN bus

Posted: Thu Apr 10, 2025 12:49 pm
by tom91
You will need to code your own master, even if you use Zombieverter. Zombieverter code base will never swell to include "BMS master" functions, the one that is maintained and released by the OI community (Damien and others)

The best route to take if you want to use the Zombieverter is to create your own BMS master for the VW MEB pack based off the SimpBMS open source code or Johannes VW code.

SimpBMS code for interfacing https://github.com/Tom-evnut/VW-bms/tree/master/VWBMSV2

Re: VCU as a BMS main on the CAN bus

Posted: Sat Nov 01, 2025 1:52 pm
by YankeeB
I'm looking at the ID4 62kwh pack for my conversion. Couldn't land up any un-complicated BMS to pack setup with minimal wiring contraption. Found the Vero BMS as the best solution as it can use the native CMUs of the ID4 pack and doesn't need to use the Vero nodes(satellites). 519kustomz on Youtube had done this on his Corvette conversion. I'm told by Vero that it's best to have all the modules from a single pack to prevent possible Canbus ID conflicts. I still need to confirm with Vero if the 100MA limit on the ID4 balance wire fuse wouldn't be an issue with the Vero.

Re: VCU as a BMS main on the CAN bus

Posted: Sat Nov 01, 2025 4:31 pm
by tom91
YankeeB wrote: Sat Nov 01, 2025 1:52 pm it can use the native CMUs of the ID4 pack a
YankeeB wrote: Sat Nov 01, 2025 1:52 pm I still need to confirm with Vero if the 100MA limit on the ID4 balance wire fuse wouldn't be an issue with the Vero.
So you concerned about the OEM fuses in the modules to be used with the OEM CMUs? Also this is very random topic to talk about this.

Are you even posing a question?

The Vero BMS is evolved from the SimpBMS, with my consent, the SimpBMS code base is fully compatible with the ID range of battery packs. Strong suggestion you use the OEM complete pack modules AND CMUs. Have seen wierd behaviour regarding balancing when using less modules then then stock.