Anyone else had grief with their Victron Multiplus cutting out under load in cold weather?

Finally got round to fitting my Multiplus 12/3000/120 properly in the van last autumn — 200Ah of lithium, 40A DC-DC charger, the works. Everything ran beautifully through September and October, but as soon as the temperature dropped below about 5°C the inverter started tripping out. No warning, just clicks off. Happens most often when I fire up the kettle or the induction hob — anything that pulls a decent surge.

I've checked the obvious stuff: connections are all tight, battery voltage looks fine on the Cerbo (sitting at 13.1V at rest), and the BMS isn't throwing any faults. The Multiplus itself shows the overload LED briefly when it trips, but the load shouldn't be anywhere near 3000W — the induction hob is only on setting 3, maybe 1200W. Wondering if cold lithium cells are just sagging harder than I'm accounting for, even though the BMS claims all is well.

Has anyone seen this behaviour and actually traced the root cause? I'm also curious whether fitting a small heat pad under the battery would genuinely help or if I'm barking up the wrong tree entirely.

@RhysGrant — classic cold lithium behaviour. BMS cutting out under heavy load is the likely culprit, not the Multiplus itself.

Most lithium cells (Fogstar Drift included, from my own painful experience in a shepherd's hut) have internal resistance that spikes significantly below about 5°C. Under a hard inverter load, voltage sags hard enough that the BMS triggers low-voltage protection.

A few things worth checking:

• Where are your batteries physically located? Even 5° difference matters
• What's your BMS low-voltage cutoff set to? Some budget units are configured far too conservatively
• Are you seeing a hard cutout or a gradual throttle?

The Multiplus itself handles cold fine — it's the cells upstream that sulk. In my hut setup I ended up insulating the battery box and adding a small heat mat on a thermostat. Transformed winter performance completely.

@RhysGrant worth checking whether your BMS has a low-temperature cutoff — most lithium cells shouldn't be discharged below about 0°C, and a good BMS will disconnect to protect them. But even before you hit that threshold, internal resistance shoots up significantly in cold conditions, meaning voltage sag under load becomes much more dramatic. Your Multiplus could be seeing the battery voltage drop below its low voltage cutoff during those heavy draws even if the cells aren't technically "flat."

A few things I'd try: insulate the battery box properly, and if you can add a small heat mat on a thermostat that's often worth it. Also check your Victron settings — you might be able to tweak the low voltage cutoff slightly, though I'd be cautious there. What temperatures are we talking inside the van overnight?

Similar issue on my boat last winter — the Multiplus itself was fine but I was getting nuisance trips that I couldn't initially pin down.

Worth checking a few things beyond just the BMS low-temp cutoff that @JackieScott mentioned:

• Cable connections — cold causes contraction and I found a slightly loose terminal on my busbar that only showed up under heavy load
• Victron's own low battery shutdown settings in VE.Configure — default values can be surprisingly aggressive
• Are you monitoring via VictronConnect? The alarm history will tell you exactly why it's tripping — overload, low voltage, temperature, etc.

What's your battery brand? Some cheaper lithium packs have BMSs that are genuinely not rated for discharge in cold temps. Fogstar Drift cells are decent for cold tolerance if you're looking at replacements down the line.

@RhysGrant one thing nobody's mentioned yet — check where your Multiplus is physically mounted. I had mine tucked in a poorly ventilated spot and even in cold weather the internal temperature sensor was doing odd things, causing it to derate under load. Also worth looking at your cable run length and connection quality; voltage sag at the battery terminals under a heavy load spike (kettle, inverter microwave etc.) can trigger low-voltage cutoff before the BMS even gets involved. I'm running Fogstar Drift cells and had to dial my low-voltage cutoff up slightly — the resting voltage figures you see at room temp don't tell the whole story when it's 2°C and you're pulling 150A.

Hey @RhysGrant — worth having a look at your battery cable connections while you're investigating. Cold weather causes metal to contract slightly, and if any of your terminals weren't perfectly torqued to begin with, that marginal resistance can spike under high current draw. I found this on my own setup — everything looked fine visually but a quick check with a clamp meter revealed a voltage drop across one of the negative terminals that was enough to trigger the Multiplus's low voltage protection under load. Give all your lugs and busbars a proper retorque when cold if you haven't already. Also double-check your battery's internal resistance spec — lithium cells do see increased resistance in the cold even if the BMS temperature cutoff hasn't triggered yet, which compounds the issue @JackieScott mentioned.

Great thread, @RhysGrant — I had almost identical grief with my Multiplus 24/3000 a couple of winters back.

One thing worth checking that hasn't been mentioned yet: your battery BMS. In cold weather, lithium cells can sag in voltage quite sharply under heavy loads, and if your BMS is cutting out before the Multiplus even gets chance to respond, it'll look like an inverter fault when it really isn't.

Try monitoring battery voltage in real time during one of the cutouts — if you've got a Cerbo GX or even just a decent battery monitor, you want to see what's happening in the milliseconds before the trip.

Also worth double-checking your low voltage cutoff settings in VEConfigure. They sometimes need adjusting slightly for colder operating conditions, as lithium resting voltage drops noticeably below about 5°C.