Can you modify bps communication with Bus with lithium batteries

Been down a similar rabbit hole recently with my backup setup. Got a Victron MultiPlus tied into a DIY lithium pack and the BMS comms have been giving me grief — specifically around baud rate mismatches on the CAN interface.

Mine's running at 500Kbps (Victron's default for their VE.Can stuff) but the BMS I picked up was preconfigured at 250Kbps from the supplier. Took me ages to figure out why the Cerbo GX wasn't seeing the battery properly — everything looked wired correctly.

Few things I've learned the hard way:

• Don't assume the baud rate matches just because the wiring is right
• Most decent BMS units (I've seen this on Daly and JK units) let you change it via a PC tool, but you'll need the right cable and sometimes proprietary software
• Termination resistors matter more than people think — especially on longer cable runs

My question for the thread: has anyone managed to manually modify BMS CAN settings on a Fogstar-sourced pack? They're not exactly forthcoming with documentation and I'm wondering if there's a hidden config mode or if it needs reflashing entirely.

Also curious whether anyone's using a CAN bridge/converter to handle mismatches rather than changing the BMS itself — seems like a cleaner solution for a backup system where you don't want to be faffing with firmware.

@MoorCamper the baud rate mismatch is a classic headache with DIY packs. Worth clarifying which BMS you're running — most of the JK and Daly units default to 9600 baud whilst the Victron VE.Bus side expects its own protocol entirely.

If you're using a Cerbo GX as the intermediary, the Venus OS handles the translation layer, but you'll need the correct VE.Direct or RS485 cable and the BMS set to the matching comms profile. Some JK firmware versions let you toggle between protocols directly in their app.

On my Ducato build I ended up using a Victron SmartShunt as a standalone monitor rather than relying on direct BMS comms — cleaner solution when the native integration gets messy. Not always ideal but sometimes pragmatic.

What's your current GX device situation?

@DucatoSolar curious what BMS options actually play nicely out of the box with the MultiPlus without needing to faff with baud rate settings? I'm running a Fogstar Drift pack and looking at adding proper DVCC comms rather than relying on the voltage-only setup I've got now. Is it purely a case of matching the baud rate in VE.Config or are there other parameters that need adjusting? I've read conflicting things about whether the MultiPlus needs a specific firmware version before it'll properly respect BMS charge limits over the bus rather than just ignoring them.

@George1972 From my experience, the JK BMS has been pretty solid with the MultiPlus via the VE.Bus BMS interface — minimal faffing required if you're using the right firmware version. The Daly units can work too but often need a USB-to-UART adapter and some patience with the baud rate settings in the configuration software.

@MoorCamper worth double-checking whether your mismatch is actually a baud rate issue or a protocol one — they can present similarly but the fix is quite different. If you're on a JBD/JIKONG type BMS, there are some community-built scripts floating around that handle the translation layer between the BMS output and what Victron expects to see on the CAN or RS485 side. What interface are you using to connect — CAN bus or RS485?

@OllieGraham91 interesting you mention the JK — I've been eyeing that up for my van build. Quick question though: are you running that comms link directly via VE.Bus or are you going through a Venus device (Cerbo GX or similar) as an intermediary? I ended up using a Raspberry Pi running Venus OS on my boat setup which gave me a lot more flexibility around protocol translation, but I'm wondering if that's overkill for a simpler van conversion where space is tight. Also did you have to do anything specific around the DVCC settings in the Victron interface to get charge current limiting to play nicely, or did it all just negotiate automatically once the BMS was recognised?