Anyone else had grief with a Victron MultiPlus cutting out under load in cold weather?

Picked up a secondhand MultiPlus 12/3000/120 a few months back and it's been brilliant — right up until the temperatures dropped last week. Running it off a 200Ah lithium bank (4x 50Ah EVE cells with a Daly BMS) and it's been handling the kettle, microwave and a small workshop heater without breaking a sweat all summer.

Now that it's properly cold — we're talking 3–4°C in the shed where it's all mounted — it's started cutting out randomly under load. No low voltage alarm, no overtemp warning on the Victron app. Just drops out for a few seconds then recovers. Happened three times yesterday when I had the microwave and a 1kW fan heater running simultaneously, so roughly 2.2–2.4kW draw.

I'm wondering if it's the BMS throttling output from the lithium cells in the cold, or something going on inside the MultiPlus itself. I've read that EVE cells can struggle below 5°C but the Daly BMS should have low-temp cutoff protection — maybe that's actually the culprit rather than the inverter? I've not got a cell-level temperature sensor set up, just the basic Daly app over Bluetooth.

Has anyone seen similar behaviour? Keen to know if insulating the battery box would sort it, or whether I need to dig deeper into the BMS settings.

FrankMurray replied:

@GrahamCole Worth checking your BMS discharge cutoff settings — lithium cells get noticeably more resistive in the cold, so your internal voltage sag under load will be more pronounced than it was in summer. Even if your resting voltage looks fine, the moment the MultiPlus pulls serious current the BMS might be seeing a legitimate undervoltage condition and tripping.

What's your low voltage disconnect set to on the BMS? And have you got Ve.Connect or VictronConnect running so you can pull the alarm history off the MultiPlus itself? That'll tell you pretty quickly whether it's cutting on low voltage, overtemperature, or something else entirely. The Victron logs are genuinely useful for this sort of fault-finding.

EcoFlow_Nerd replied:

@GrahamCole Had almost exactly this with my static caravan setup last winter — turned out my cable runs were undersized and the voltage drop under load was already borderline. Cold weather just pushed it over the edge. The MultiPlus is ruthless about low voltage — it'll shut off faster than you can say "where's my torch?"

Worth checking: have you got the Victron Connect app talking to it? The history tab shows low voltage trip events with timestamps, which is dead useful for diagnosing whether it's a sustained sag or a sudden spike load triggering it.

Also — what cable gauge are you running between the cells and the inverter? With a 3000W unit you really want to be thinking 70mm² minimum, ideally 95mm². Any resistance in those connections gets much worse when everything's cold and stiff.

AndyGraham replied:

@GrahamCole One thing nobody's mentioned yet — check your DC cable run and connections. Cold weather causes slight contraction in crimped lugs and busbar connections, and what was a marginal joint in summer becomes a voltage-dropping liability under heavy load in winter. I found exactly this on my shepherd's hut build; a 3000W inverter pulling 250A+ will expose any weakness ruthlessly.

Use a thermal camera or even just your hand carefully across connections immediately after a cutout — warm spots are the giveaway. Re-torque all terminals while you're at it; Victron specify torque values in the manual and they're worth following properly.

Also worth logging via VictronConnect — the MultiPlus records low DC voltage events. If it's tripping on under-voltage rather than overtemperature, that narrows it down considerably.

RhysGrant replied:

@GrahamCole One thing worth adding to what's already been said — have a look at your MultiPlus low voltage shutdown threshold in VEConfigure. The default settings are often configured with flooded lead-acid in mind, and the trip voltage can be surprisingly high relative to what your lithium bank actually needs. In cold weather your cells will sag harder under load, which can nudge you over that threshold even when there's plenty of capacity left. Try logging your DC voltage during a cutout using a Cerbo or even just a cheap Bluetooth shunt — seeing exactly what voltage it's hitting at the moment it trips will tell you a lot. Might save you chasing a problem that's actually just a configuration tweak.

BerlingoConvert replied:

@GrahamCole What BMS are you running on those EVE cells? On my narrowboat I had a JK BMS that was tripping the whole bank offline when temps dropped — looked exactly like an inverter fault but was actually the BMS seeing a voltage sag under load and pulling the plug. The MultiPlus got the blame for ages before I figured it out.

Worth checking whether the cutout is actually coming from the BMS side rather than the MultiPlus itself. Does your Victron throw any fault codes on the VictronConnect app when it happens, or does it just go dark with nothing logged? That would tell you a lot about where the fault actually originates.