Connecting BSLblatt batteries and two smartsolar Mppt's to Multiplus Gx

Got myself in a bit of a tangle here and wondering if anyone's been through something similar.

I'm in the process of setting up a system on my narrowboat with two Victron SmartSolar MPPTs and a Multiplus-II GX, and I've decided to go with BSLBatt lithium batteries. On paper it all looks lovely, but I'm hitting what seems to be a CAN bus communication issue between the batteries and the GX unit.

From what I can gather, the BSLBatt batteries want to communicate at 500 kbps, but the Victron GX side of things defaults differently depending on how you configure it. Has anyone actually got this working cleanly? I've been digging through the VRM portal settings and I can see the BMS isn't being recognised properly — it shows up intermittently at best.

A few specific questions:

• Do I need to set the VE.Can port to 500 kbps manually in the GX settings, and does that then cause any conflicts with the two MPPTs if they're also on that bus?
• Would it be better to run the MPPTs via VE.Direct instead and keep the CAN bus purely for the battery BMS comms?
• Anyone know if BSLBatt have a specific RJ45 pinout for UK-spec units? The documentation I received is a bit vague.

Both MPPTs are the 100/30 SmartSolar models if that's relevant. The boat's 12V system, 200Ah battery bank.

Feels like I'm one setting away from it all clicking into place but I can't quite get there — any pointers from someone who's cracked this would be brilliant!

@LindaClark90 classic narrowboat wiring spaghetti — the key thing with BSLbatts and a MultiPlus-GX is making sure your BMS is talking to the Victron ecosystem via the VE.Can or VE.Bus port, otherwise the Multi won't know when to back off charging and you'll cook your cells 🔥

Both MPPTs should wire directly to the battery busbars (not daisy-chained), and use VE.Direct cables to get them visible in the GX portal — then DVCC does the heavy lifting coordinating charge current across everything automatically.

Grab the Victron DVCC guide from their docs, it's basically the bible for multi-source setups like yours.

@LindaClark90 both MPPTs need to be on the same VE.Direct network as the GX — if they're not talking to it properly, the Multi won't know what the solar is doing and you'll get phantom load readings that make absolutely no sense at 2am when you're trying to work out why your batteries are at 40%.

Key things I'd check:

• DVCC enabled in VE.Config — this is what lets the GX coordinate charge sources
• BSLbatt BMS connected via VE.Bus BMS or CANbus depending on your model
• Both MPPTs set to identical absorption/float voltages (let DVCC handle it ideally)

Done similar on my narrowboat with Fogstar Drift cells and twin Victron MPPTs — the GX basically becomes the conductor once DVCC is sorted, everything else falls into line.

@LindaClark90 what model BSLbatts are you running? That'll make a big difference to how you set up the charge parameters on the MPPTs. On my boat I had a nightmare getting the battery profile dialled in correctly before everything played nicely together.

Also — are you using a VE.Smart network between the two SmartSolars? They can sync charge states with each other via Bluetooth which helps avoid them fighting each other. Worth checking that's configured before you go too far down the troubleshooting rabbit hole.

What does the Cerbo GX (or built-in GX?) show for each MPPT in the device list — are both appearing there at all?

@LindaClark90 had a similar headache on my narrowboat build — one thing that caught me out was the charge voltage settings conflicting between the MPPTs and the MultiPlus when they weren't properly networked together via VE.Smart. Are yours networked so they're actually synchronising charge parameters, or are they operating independently? If the MPPTs aren't sharing data with the Multi, you can end up with them fighting each other over absorption voltage. Worth checking in VictronConnect that both MPPTs show the networked lightning bolt icon. Also, what are you using for BMS communication — is the BSL BMS talking to the GX via CAN or are you relying on manual charge limits?