Jk BMS B2A8S20P + JP-Plink board to connect with Cerbo GX

So here's where I'm at — finally pulled the trigger on a JK BMS B2A8S20P for the static van build, paired it up with the JP-Plink board to get it talking to my Cerbo GX. Using the Victron Type A cable into the BMS-CAN port, set the CAN protocol to option 4 (Victron) on the JK side, and... nothing. Cerbo's just staring blankly at me.

A bit of background: the van's running a 48V LiFePO4 pack I've built myself — Fogstar cells, decent quality — and the rest of the system is full Victron (Multiplus II, SmartSolar, the works). Everything else talks to the Cerbo without complaint. It's specifically this BMS integration that's gone quiet.

Things I've already checked:

• Cable pinout — gone over it twice
• CAN protocol setting on the JK app — definitely on 4
• Cerbo firmware — updated last week
• VE.Can port set to 500 kbit/s in Remote Console

Still showing no BMS data whatsoever on the GX Touch. No battery widget, nothing populating under Devices.

What I'm not sure about is whether the JP-Plink board needs any specific configuration beyond what's in the JK app, or whether there's a known firmware version issue with this particular BMS model communicating with recent Cerbo firmware. I've seen vague mentions of termination resistors mattering on CAN bus runs — is that likely to be the culprit given the cable's only about a metre long?

Anyone actually got this specific combo working in a UK off-grid setup? Step-by-step would be genuinely appreciated rather than

@BordersNomad interesting setup — I've been eyeing the JK BMS for my narrowboat build and the Cerbo GX integration is exactly what's holding me back from pulling the trigger.

Couple of questions if you don't mind:

• Does the JP-Plink board handle the RS485 to VE.Direct conversion cleanly, or are there any quirks with the Cerbo recognising it reliably?
• Which firmware version are you running on the JK? I've seen reports that older firmware causes dropouts
• Is the Type A cable the specific Victron VE.Direct one, or something third-party?

I'm particularly interested because on a narrowboat I'd need rock-solid comms — if the BMS drops off the Cerbo mid-cruise that's a problem. Any instability you've noticed under load would be really useful to know about before I commit to the same stack.

@BordersNomad great project — the B2A8S20P is a solid choice for a static van build, that 20A balancing current is genuinely impressive at the price point.

One thing worth confirming early: make sure the JP-Plink firmware is current before you attempt pairing with the Cerbo. I had a frustrating afternoon with my own Cerbo GX integration where the BMS was simply not appearing on the VRM portal — turned out to be a firmware mismatch rather than any cabling issue.

Also double-check your VE.Direct port assignment in Venus OS. With multiple devices connected it's easy to have the Cerbo scanning the wrong port entirely.

What cell chemistry are you running — LFP presumably? That'll affect your BMS profile settings considerably once you're into the Victron ESS configuration side of things.

@BordersNomad what cable settings are you using on the Cerbo side? I had such a nightmare getting my JK to show up properly — kept appearing as unknown device until I fiddled with the baud rate in Venus OS.

Also worth double-checking the JP-Plink firmware version, there was a batch a while back that had dodgy comms. Mine was one of them, obviously 🙄

The Type A cable should be fine but make sure you've not got a ground loop situation — caused me endless grief on the boat before I sorted it.

@FinnTaylor78 narrowboat install will be fine, just factor in the damp. Learned that the hard way.

@BordersNomad which firmware version is on the JK? I had a similar setup in my static van and early firmware on the B2A8S20P had a habit of dropping the RS485 connection intermittently — showed up fine in VictronConnect but kept disappearing from the Cerbo device list.

Worth checking the baud rate on the JP-Plink board matches what the Cerbo expects — mine defaulted to 9600 but needed bumping to 115200.

Also make sure you're on VenusOS 3.x minimum, older versions had patchy support for the JK via that Plink board. Once I sorted those two things it's been rock solid — cell voltages, SOC, temps all reporting cleanly through the Cerbo.

What are you using for your battery bank — how many cells in the pack?

@BordersNomad my JP-Plink took about 20 minutes of me staring blankly at it before I realised the little jumper on the board needed moving — check that before you go down the firmware rabbit hole @BoatMick is hinting at.