MultiPlus and Smart NG + VE.Bus BMS no battery monitor

Running into something similar with my shepherd's hut setup and wondering if anyone else has hit this wall.

I've got a MultiPlus-II paired with a Smart BatteryProtect and VE.Bus BMS, and since updating VictronConnect I've lost the ability to select a battery monitor entirely. The dropdown just doesn't show the MultiPlus as an option anymore — it's greyed out, and the "automatic" selection has vanished too. Getting that same message about an unavailable monitor.

From what I can piece together, when the VE.Bus BMS is active it takes over certain control functions and essentially locks out the MultiPlus from acting as the battery monitor — something to do with how the BMS asserts itself on the VE.Bus network. But I'm not 100% sure if this is expected behaviour or something that's gone wrong after the firmware update.

A few things I'm unclear on:

• Should I be running a Cerbo GX or SmartShunt as the designated monitor instead, with the BMS just handling protection duties?
• Has a recent firmware push on the MultiPlus-II broken something here, or is this by design?
• Anyone running Fogstar or similar lithium cells with this exact BMS combo who's found a clean workaround?

The hut is my full-time off-grid power source so I'm keen to get proper SoC monitoring back — flying blind on battery state isn't ideal, especially heading into winter.

Would appreciate hearing from anyone who's navigated this. Is a SmartShunt the obvious answer here, or am I missing something more fundamental in the system config?

Hey @Jock30, looks like your post got cut off there - we're all left hanging! 😄 Would love to help once you finish describing your setup and what issue you're actually hitting.

That said, the MultiPlus-II with VE.Bus BMS combination is one I know reasonably well from my own setup, so do share the full details when you get a chance. Particularly useful to know which firmware version you're running on the MultiPlus, and whether you've got a GX device (Cerbo, Venus, etc.) in the mix - that makes a big difference to how the battery monitoring behaves with the VE.Bus BMS. Also worth mentioning your battery bank size and chemistry if relevant.

@Jock30 Classic Victron puzzle — the VE.Bus BMS is a bit of a drama queen and deliberately disables the battery monitor function in the MultiPlus when it's in charge, because it wants itself to be the sole authority on battery state (fair enough really, it's got the cell-level data).

Fix is to use a BMV-712 or SmartShunt on the DC bus instead — that becomes your actual monitor whilst the VE.Bus BMS keeps doing its cell protection thing. Wire it correctly on the negative rail and configure it in VictronConnect as your battery monitor; the MultiPlus then pulls SOC data from that via VE.Smart networking.

Finish your post though mate, there may be a specific twist with the Smart BatteryProtect in that chain worth addressing! 🔋

@RetiredChef is onto something there. Ran into exactly this with my van build — VE.Bus BMS takes over the show completely and the MultiPlus-II defers to it, which is why the battery monitor greys out in VictronConnect.

The fix that worked for me was adding a SmartShunt into the system and letting that handle State of Charge tracking instead. The BMS still does its protection duties, the MultiPlus does the heavy lifting, and the SmartShunt feeds everything into VRM as a dedicated battery monitor.

@Jock30 finish your post though — there's a few variations of this setup and the devil's in the wiring details. Particularly curious whether you've got the Allow-to-Charge / Allow-to-Discharge lines running correctly to the BMS assistant in the MultiPlus, because that catches a lot of people out.

@Jock30 finish your post before we all go grey waiting! 😄

That said, @RetiredChef and @WildHermit have pointed you in the right direction. Worth noting the specific mechanism: the VE.Bus BMS communicates via the VE.Bus port and essentially overrides the MultiPlus's own state-of-charge tracking — by design, not bug. Victron's rationale is that the BMS is the authority on battery state.

The fix most people land on is adding a BMV-712 or SmartShunt on the DC side for standalone SOC monitoring — it operates independently of the VE.Bus architecture entirely. My own static caravan setup runs a SmartShunt alongside a MultiPlus-II and it's rock solid; VE.Bus BMS handles protection, SmartShunt handles monitoring. Clean separation of duties.

Finish describing your exact symptom though — there are a couple of distinct failure modes here and the solution differs depending which one you're hitting.

@Jock30 your post got cut off so I'm guessing at the specifics, but worth clarifying one technical point that hasn't been mentioned: the VE.Bus BMS requires a dedicated BMS Assistant loaded onto the MultiPlus-II via VEConfigure. Without it, the BMS-controlled charge disconnect and load disconnect signals won't function correctly regardless of what the monitor shows.

Also — if you're using a Smart BatteryProtect on the load side, be aware it must be in Li-ion mode and wired so the VE.Bus BMS Load Disconnect output drives it directly. Many people wire this wrong.

The battery monitor situation @RetiredChef mentioned is by design — Victron intends you to rely on the BMS for state-of-charge with this topology rather than a standalone BMV-712.

Finish your original post and I can give more precise advice.