Smartshunt pass thru but no readings

Had almost the exact same head-scratcher on my narrowboat last spring when I retrofitted a Victron SmartShunt into my leisure bank setup.

Everything passing through, loads working, solar coming in — but the shunt was sitting there completely dumb. No readings, just silence on the Victron Connect app.

Turned out I'd missed something embarrassingly simple: the small signal wire (the 9-15V supply cable, the thin one to the B1 terminal) wasn't properly connected. The shunt needs that separate feed to actually power its brain. It's not enough just to have current flowing through the main terminals — without that signal wire getting a clean positive feed, it just sits there like a very expensive bit of copper bar.

Worth checking:

• Is your B1 signal wire fused and connected directly to the battery positive?
• Have you got a solid negative reference on the case/B2 side?
• Bluetooth showing the device at all, or genuinely zero presence in the app?

If it's appearing in VictronConnect but showing dashes rather than figures, that's often a calibration/synchronisation issue rather than a wiring fault — you'd want to force a "synchronised" state in the app settings.

If it's not appearing at all, I'd start suspecting that signal wire or a dodgy fuse in the supply.

Also worth double-checking your battery negative routing — all your negative loads need to return through the shunt, not bypass it. Inverters are a classic culprit for sneaking a direct negative connection and skewing your readings completely.

Anyone else had similar grief with theirs? Curious whether this is catching more people out since the campervan solar boom took off.

@Deano the classic "it works but doesn't know it works" — nine times out of ten you've got the negative cable from something bypassing the shunt entirely, mate.

Check that every negative path routes through the shunt's load terminal — not directly back to the battery. Even one rogue chassis earth will throw the whole lot off. Had this exact faff on my boat; turns out a previous owner had helpfully wired the bilge pump straight to the battery negative like some kind of anarchist.

The SmartShunt is only as clever as the wiring feeding it.

@Deano mate, narrowboat twin bank setups are basically a rite of passage for this exact meltdown — check your "Battery negative" terminal on the shunt is the only path back to the battery, because if you've left a sneaky direct chassis ground anywhere it'll happily bypass the shunt and read absolutely nowt while your loads laugh at you.

@Deano had this exact faff with my cabin setup last year. The SmartShunt needs to be the single point of return for all negatives — battery, loads, everything. Miss one stray negative going direct to the battery terminal and it's blind to that current. Doesn't matter if it's tiny either.

Also worth checking in the VictronConnect app that the shunt size is configured correctly under battery settings — mine was defaulting to wrong capacity and throwing daft readings even after I'd sorted the wiring.

Narrowboat installs are notorious for "helpful" previous wiring that bypasses stuff randomly. Follow every negative back like you're investigating a crime scene. Methodical, annoying, but there's no shortcut.

@Curly38 nailed the single return point thing — and I'd add: don't forget the chassis/hull bond if you've got one. On my cabin setup I had a sneaky earth strap going directly to the battery negative, completely bypassing the shunt. Spent a whole afternoon convinced the Victron app was broken before I found it hiding behind the battery box like it was ashamed of itself.

Also worth checking the VictronConnect app — make sure the shunt's battery capacity and charged voltage are actually configured, not just left on defaults. It'll work but the SOC will be reading absolute nonsense.

Pull every negative connection and trace each one. Every. Single. One. It's tedious but there's no shortcut unfortunately.

@CamperSam raises a valid point on the hull bond, but there's another one people consistently miss — the small signal wire (the negative sense lead going to the aux terminal on the shunt). If that's not connected to your load-side negative, the shunt has no reference point and VictronConnect just sits there showing dashes.

Also worth checking: are you monitoring via Bluetooth only? Some Android devices struggle to maintain a stable connection long enough to populate the initial sync. Try the Victron Connect app on a different device, or give it a full 30-second stationary connection before dismissing it as a wiring fault.

In my tiny house backup setup using a SmartShunt 500A, I had this exact symptom — turned out the sense wire had been accidentally landed on the battery-side negative lug rather than the load-side. Swapped it over, readings populated instantly.