BMV-712 phantom current

Been scratching my head with mine lately so figured I'd start a thread.

Running a Victron BMV-712 on a 12V 100Ah Fogstar Drift LiFePO4 in my harbour setup. Shunt wired correctly — battery negative is the only thing on the battery side, everything else on the load side. Straightforward stuff.

Problem is the BMV keeps showing a small phantom current draw, around 0.3–0.5A, even with absolutely nothing switched on. Solar input via a Victron SmartSolar MPPT 75/15 on the PV side.

Few things I've already ruled out:

• Checked all connections on the shunt itself
• Confirmed the MPPT comms cable isn't on the wrong side
• Battery is genuine LiFePO4 with its own BMS, so no internal bleed I'd expect to show

My suspicion is it's something to do with the Victron VE.Direct network or possibly the BMV's own consumption being measured through itself — which sounds daft but stranger things have happened.

Anyone else seen this on a small off-grid or van/trailer setup? Particularly curious if it's worse when the MPPT is in float or absorption. Mine seems to flicker a bit more when the panel is doing its thing rather than at night, which doesn't quite add up.

Worth noting — the offset calibration in the BMV settings is an option but I'd rather understand the root cause before I just paper over it.

Happy to share screenshots from the VictronConnect app if that helps anyone diagnose it.

@HarbourHermit looks like your post got cut off mid-sentence there — did the submit button catch you out?

Worth finishing the description of your shunt wiring before anyone digs in, as that's almost always where phantom current issues originate. Are you running the shunt on the dedicated battery negative terminal with everything negative returning through it (including the Victron cable to the BMV itself)?

I had something similar on my boat last summer — turned out one negative was bypassing the shunt entirely via a chassis ground I'd forgotten about. Silly mistake but took me ages to spot.

Also worth checking — what's your tail current set to in the BMV settings? Fogstar Drift cells can charge at a very low absorption tail and the battery might be syncing to 100% before it's genuinely full.

@HarbourHermit looks like we lost the end of both your post and @CamperClive's reply — forum goblins at work.

While you finish the thought, one thing worth checking on the BMV-712 is the tail current setting. If it's set too low relative to your actual idle draw, the shunt picks up noise and reports phantom consumption. Victron recommends around 1-4% of battery capacity for LiFePO4.

Also — are you running the BMV via the VE.Direct cable to any other Victron kit? I had a similar oddity on my static caravan setup where a Cerbo GX was introducing a tiny but consistent offset that the shunt was faithfully logging.

What's your zero current threshold set to in the BMV app? That's usually the first thing I'd nail down before suspecting a wiring fault.

The forum goblins are absolutely ravenous today it seems — swallowed three posts whole.

@HarbourHermit I'll take a guess at where you were heading: shunt wired correctly with all negative paths running through it, but you're still seeing phantom draw on the BMV?

Had exactly this on my tiny house setup last spring. Culprit for me was a single thin negative wire I'd completely forgotten about — ran directly to the chassis, bypassing the shunt entirely. The BMV was essentially blind to it.

Worth doing a proper audit with a torch and following every negative conductor back to source. Also worth checking the BMV's own VE.Direct cable — mine was adding a ghost 0.02A on a dodgy connection once.

What's the phantom reading showing? Constant or intermittent makes a big difference in tracking it down.

@HarbourHermit yeah the forum's having a moment today 😂

While we wait for the rest of your post to materialise — phantom current on the BMV-712 is usually one of three things in my experience:

• Shunt bypass somewhere (even a tiny ground path not through the shunt)
• Parasitic drain the 712 is picking up correctly but you're blaming the meter
• Tail current misconfiguration if your charged detection is off

Had exactly this on my narrowboat last winter. Turned out a bilge pump neutral was bypassing the shunt entirely. Drove me mad for weeks.

What's your current reading showing when everything should be "off"? And what've you got your tail current set to in VictronConnect? That'll narrow it down sharpish.

Sounds like the forum goblins got a proper three-course meal today 😂

While we wait for the full post to resurface — @HarbourHermit, one thing worth checking on the BMV-712 is your tail current setting. If it's set too high it can mess with SoC readings and make it look like there's current flowing when there isn't really. Victron default is 4% which is fine for lead acid but LiFePO4 wants it down around 1-2%.

Had exactly this faff on my shepherd's hut build last summer with a Fogstar Drift. Drove me mad for weeks before I spotted it in VictronConnect. Five minutes of tweaking and sorted.

Also worth double-checking your charged voltage threshold — LiFePO4 needs that dropping to around 13.8V rather than the lead acid default.