ESS - DVCC / Battmonitor - was stimmt denn nun?

Been wrestling with this one on my van build for a couple of weeks now and it's doing my head in.

Running a Multiplus II with a Cerbo GX, SmartShunt, and a 48V LiFePO4 pack with a JK BMS — the BMS isn't talking directly to the Cerbo, just the SmartShunt doing the monitoring legwork.

The question that's haunting me: which device should actually "own" the battery data in DVCC?

With DVCC enabled, the Cerbo wants a trusted battery monitor. I've got the SmartShunt set as the battery monitor, which makes sense on paper — it's sitting right on the negative busbar, seeing everything. But when I dig into the ESS settings, there's this nagging feeling I'm double-counting or misconfiguring something, especially around State of Charge synchronisation.

A few things I'm trying to untangle:

• Should the SmartShunt remain the selected battery monitor in DVCC, or does that cause conflicts when ESS is doing its own calculations?
• Without the JK BMS connected to the Cerbo, am I missing out on proper cell-level voltage protection being fed back into the charge logic?
• Does DVCC's SVS (Shared Voltage Sense) actually help here, or just muddy the waters further?

I've read the Victron documentation twice and somehow come away more confused each time — which is impressive, really.

Anyone running a similar topology — AC-coupled PV, no direct BMS comms to the GX device — who's cracked how to structure this properly? Genuinely curious whether connecting the JK via a RS485-to-USB adaptor is

@VitoBuild the thread title's in German but I'll answer in English — the core issue is that with DVCC enabled, the Cerbo takes the SmartShunt's SOC as the system-wide battery monitor, overriding what the Multiplus sees internally. This is correct behaviour, not a bug.

Key thing people miss: if your JK BMS is connected via CAN or VE.Direct, Victron will prefer the BMS data over the SmartShunt. Check your DVCC settings — System Monitor dropdown will show you what's actually being used.

On my narrowboat I run a SmartShunt as backup monitor with the BMS as primary. Once I stopped fighting it and let DVCC manage charge current via SVS and SCS, everything settled down properly.

What's your JK connected via? That'll determine which path the Cerbo's actually trusting.

@VitoBuild had exactly this confusion setting up my static caravan system last year. The bit that clicked for me — with DVCC on, the SmartShunt becomes largely decorative for charge control purposes. The Cerbo is trusting the JK BMS figures instead.

What actually sorted mine was making sure the Battery Monitor setting in the DVCC menu was explicitly set to the JK BMS, not left on "Automatic." Automatic sounds sensible but it can grab the wrong source depending on firmware versions.

Also worth checking: does your JK BMS have a Victron-compatible UART/RS485 cable or are you running it via some Bluetooth workaround? That affects whether the Cerbo is getting real-time data or polling on a delay — which shows up as that maddening SoC drift you probably noticed.

Really useful thread — I've been going round in circles on this same question for my tiny house build.

One thing I'm still not clear on: when DVCC is active and the Cerbo GX takes over as the "trusted" battery monitor source, does the SmartShunt data still display normally in VRM? Or does it effectively get demoted to just a sensor feeding data upstream?

Asking because I've got a Fogstar Drift pack with an external JK BMS and I'm trying to work out whether I still get accurate SOC history in VRM for monitoring purposes, even if the SmartShunt is no longer "in charge" of the control loop.

@ShaunDixon — did your static setup retain full SmartShunt logging once DVCC was sorted, or did you lose granularity on the data?

@VitoBuild the piece that often gets missed: when DVCC is active and your JK BMS is talking to the Cerbo via the correct protocol, the BMS becomes the authoritative SOC source — the SmartShunt gets demoted to a "backup" role essentially. This is correct behaviour, not a fault.

What catches people out is the SmartShunt still displays its own SOC figure, which diverges from what VRM shows, causing apparent contradictions.

My recommendation: go into your Cerbo settings → System Setup → Battery Monitor and explicitly confirm which device is selected. With a communicating BMS, select the BMS. Reserve the SmartShunt for current/voltage monitoring rather than SOC authority.

@ShaunDixon is right that DVCC fundamentally changes the control loop — the CVL/CCL/DCL limits pushed by the BMS override everything else in the charge chain.