Victron Multiplus-II 48v tripping under EV charge load — anyone else had this?

Finally got my EV charging setup running off the battery bank but the Multiplus-II 5000VA keeps throwing an overload fault when the EVSE ramps up past about 3.5kW. Bank is 16x 280Ah EVE cells in 48v configuration, so capacity isn't the issue. The Victron is set to 230v AC out, transfer switch enabled, and I've got solar feeding in via a SmartSolar 150/45.

Checked the VictronConnect logs and it's showing the AC output current hitting the limit briefly during the EVSE ramp-up phase — that initial inrush when the car starts drawing. Tried dropping the EVSE to 13A via the app which helps but defeats the point really. Feels like the inverter should handle this given its rated output.

Wondering if it's a configuration issue in the CCGX or whether the weak link is actually my DC cabling — I used 70mm² for the main runs but there's a short section of 50mm² I bodged in temporarily and never replaced. BMS is a Daly 200A active balancer unit, so that could also be cutting out momentarily under spike load and the Multiplus sees it as a fault.

Has anyone tuned the overload trip sensitivity in VEConfigure, or is there a specific PowerAssist setting that smooths out the inrush? Getting a bit fed up of resetting faults every time I plug the car in.

@VitoProject had almost identical grief on my narrowboat when I added a Type 2 EVSE last spring.

Few things worth checking:

• PowerAssist settings in VE.Configure — if your AC input limit is set too low it'll trip before the inverter even tries to cope
• What's your DC bus voltage under load? If cells aren't balanced properly the BMS might be pulling the plug before Victron even reports a fault
• The Multiplus-II 5000 is rated 5kVA but continuous draw at 3.5kW plus any other boat loads could be nudging limits depending on ambient temp

Also — is this grid-tied or pure off-grid? If you've got shore power connected, check the input current assistant configuration. Mine was throttling the inverter unnecessarily.

What BMS are you running with those EVE cells?

@VitoProject this is almost certainly a PowerAssist configuration issue rather than a genuine overload. In VE.Configure, check your AC input current limit — if it's set too conservatively, the Multiplus tries to compensate from the battery when grid (or generator) input gets restricted, then trips when the combined draw spikes during EVSE ramp-up.

Also worth checking: what's your DC input low voltage cutoff set to? EVE cells at 16S will sag noticeably under sudden 3.5kW+ demand, and if the BMS is momentarily pulling back on discharge current during that ramp the inverter sees it as a supply fault rather than overload.

In my cabin setup I had identical behaviour — sorted it by setting a soft current limit in the EVSE (using an Indra unit here) to slow the ramp rate, giving the Multiplus time to stabilise.

What BMS are you running?

@VitoProject worth checking your AC input current limit in VE.Configure too — if it's set low (say 16A) and PowerAssist kicks in late, there's a brief moment where the inverter is carrying the full ramp-up spike alone before assist catches up.

Also, what does your DC bus voltage look like at the point of fault? If your BMS is throttling output current and the voltage sags below ~47v under that sudden load, the Multiplus can trip on low battery before overload protection even becomes relevant.

On my shepherd's hut setup I had similar nonsense with a smaller Multiplus — turned out the transfer switch delay was creating a gap that the inverter couldn't bridge cleanly. Tightening that in VEConfigure3 sorted it.

Grab a VRM screenshot of the moment it trips if you can — makes diagnosis much easier.

@VitoProject one thing nobody's mentioned yet — have a look at your ESS assistant settings if you're running ESS. Specifically the "Minimum SOC" threshold. If your bank dips anywhere near that floor when the EVSE ramps up, the system can get a bit confused and chuck an overload fault even though the cells are perfectly capable.

Also, what's your BMS configured for as a max discharge current? If the BMS starts throttling output right as the EVSE peaks, the Multiplus gets caught short and trips. Worth logging via VRM or even just the GX device display to see exactly what's happening at the moment of fault — the live graphs are brilliant for catching these split-second events.

What GX device are you running alongside it?

@VitoProject one thing I'd add — check your DC input low voltage thresholds in VE.Configure. If they're set conservatively (easy to do with LiFePO4 cells), the Multiplus can start throttling output before it actually needs to, which under a sudden load spike like an EVSE ramp-up can trigger a fault rather than a graceful reduction.

Also worth looking at the inverter DC shutdown voltage versus your battery BMS low-voltage cutoff — you want the Multiplus to back off before the BMS trips, not after. With 16x 280Ah EVE cells you've got plenty of capacity, so those thresholds might just need nudging upward a touch to reflect your actual cell characteristics. What firmware are you running on the Multiplus? Some older versions had slightly aggressive overload detection behaviour.

Good shout from @OakTel on the voltage thresholds — I'd add specifically check your DC input low shutdown vs DC input low pre-alarm values. If they're close together the Multiplus panics before the BMS even blinks.

One thing nobody's touched on yet — what's your battery cable sizing and run length? With 16x EVE cells you've got the capacity but if your DC cabling is undersized you'll see a voltage sag under that 3.5kW+ load that looks to the inverter like a genuine undervolt condition even though the cells themselves are fine.

I had almost identical symptoms on my narrowboat build — turned out my negative busbar connection had a dodgy crimp. Showed fine at low loads, fell apart at ~70A draw. Thermal camera sorted that one in about 30 seconds. Worth a look before diving deep into VE.Configure rabbit holes.