Instalación exporta con bateria al 60%

Bit of an odd one this, and wondering if anyone else has run into something similar.

My cabin setup has been running well for months — Victron Multiplus-II 48/3000, a pair of Fogstar Drift 48V batteries, and a SmartSolar 150/100 doing the heavy lifting on the solar side. All talking nicely through a Cerbo GX.

Started noticing last week that the system was pushing export back to the grid (I'm on a G98 connection for the cabin supply) even when the batteries were sitting at around 60%. Didn't think much of it at first, assumed a gremlin in the schedule. But it's happening consistently now — sunny afternoon, batteries nowhere near full, and the inverter is exporting rather than topping up the bank.

Dug into VRM and the ESS settings look correct. Feed-in excess solar is ticked, minimum SOC is set to 20%, nothing that should trigger export at 60%.

My suspicion is it's either:

• A BMS communication issue telling the Multiplus the batteries are fuller than they are
• Something screwy in the ESS assistant version I'm running
• A firmware update that quietly changed behaviour

Has anyone seen their Victron system exporting prematurely like this? Particularly interested if you're running Fogstar or Pylontech-style LiFePO4 with DVCC enabled — I wonder if the cell balancing data is confusing things.

Happy to share VRM screenshots if it helps diagnose. This community has saved me more than once, so let's have a proper dig into it.

@MountainHermit the thread title's in Spanish but I'll assume that's a paste error and crack on...

Classic symptom of the Multiplus-II hitting its DC input low voltage threshold early. Even if your Fogstar Drifts show 60% SoC, if there's any voltage sag under load the inverter will interpret that as a depleted bank and start exporting to shed the load.

Check two things in VE.Configure:

• DC input low shutdown — should be around 44V for 48V LiFePO4
• DC input low restart — set maybe 2–3V above that

Also worth checking your battery cable gauge and termination. Voltage drop at the Multiplus terminals vs the battery terminals is often the real culprit, especially if your runs are longer than a metre or so.

What does the Fogstar BMS reporting in the Victron app — is it talking properly via CANbus or just a basic connection?

Seen this exact behaviour on my own Multiplus-II. Worth checking your ESS assistant settings — specifically the "Minimum SOC" and "Feed-in excess solar" options in VE.Configure. If feed-in is enabled and the grid setpoint is misconfigured, it'll push power out even mid-charge cycle.

Also double-check your DVCC settings in the Cerbo/Venus. Had mine exporting at weird SOC points because the BMS charge current limit wasn't being respected properly — Fogstar Drift's BMS can occasionally send odd signals during balancing.

Quick thing to rule out: is the 60% consistent or does it drift? If it's always exactly 60% that points more to a threshold setting than a comms glitch.

@VitoSolar already pointing at ESS which is the right rabbit hole — but also check your grid setpoint in VEConfigure. Had this exact thing on my motorhome build (different scale but same Multiplus-II behaviour) where it was pushing export because the setpoint was configured wrong and the system thought it was "helping" rather than holding.

Also — are your Fogstar Drifts on the latest firmware? There was a period where BMS comms over VE.Can were a bit flaky and the Multiplus wasn't reading SOC accurately. It'd think 60% was actually higher and start exporting to compensate.

Check Venus OS logs too. GX device will tell you exactly what triggered the export event if you dig into the right menu.

Right so this happened to me during my van conversion days before I moved everything into the cabin — I'd be scratching my head wondering why the inverter was cheerfully dumping power back to the grid whilst the batteries sat there looking smug at 60%.

Turned out to be a Dynamic ESS quirk where it was second-guessing itself based on a dodgy weather forecast. Victron's algorithm essentially thought "ooh cloudy tomorrow, better save some room" — except it was July and perfectly sunny.

Worth checking in the VRM portal whether Dynamic ESS is actually enabled on your system, because sometimes it sneaks on during firmware updates without making a fuss about it. If it is, try switching to the standard ESS mode temporarily just to isolate whether that's your culprit before diving deeper into the rabbit hole @VitoSolar and @OffGridMax are already excavating.

Good shout from @OffGridMax and @VitoSolar — both worth checking first.

One thing nobody's mentioned yet: the Fogstar Drift's BMS can signal a charge current limit to the Multiplus via DVCC even when the displayed SOC looks fine. If the BMS decides conditions aren't ideal (temp, cell delta, whatever) it quietly throttles charge acceptance — the inverter then sees excess and pushes it to grid rather than battery.

Check your DVCC logs in VRM and look at Max Charge Current — if it's dropping unexpectedly around that 60% mark, that's your culprit.

Had similar grief with my own Fogstar setup until I realised one cell group was running slightly warm. Sorted the ventilation and the phantom exports stopped.