Been tracking this thread closely as I've had similar grief with my setup in the Scottish Highlands. Running a Victron SmartBMS in my shepherd's hut and noticed the protection logic gets quite aggressive once temperatures drop below 5°C.

The issue, as I've come to understand it, isn't really a fault—it's the BMS doing its job too well. Lithium cells genuinely do behave differently in cold conditions. Resistance increases, which means the BMS detects higher discharge currents and triggers low-temperature cutoffs earlier than you'd expect. Victron's firmware is conservative by design, which is sensible from a battery longevity perspective but absolutely maddening when you're sat in the dark because your heating just tripped the system.

What I've implemented that's helped considerably:

Passive insulation around the battery box made a real difference—I used rockwool batts, nothing fancy. Keeps ambient fluctuations from hitting the cells directly. Temperature sensor placement matters too; mine was positioned poorly initially, reading the coldest spot rather than the actual cell temperature.

Configuration tweaks through VictronConnect have also helped. I adjusted the low-temperature current limit upwards slightly and increased the cold weather protection threshold by a couple of degrees. Not recommending anyone blindly copy settings, mind you—depends entirely on your chemistry and use case.

Worth checking whether you've actually got genuine Victron units as well. Counterfeit BMS modules circulate occasionally, particularly through certain online retailers. If your system's behaving erratically, that's worth ruling out.

Would be interested hearing what specific models folks are running and their ambient conditions. Might help identify whether this is a chemistry issue or something more systematic.

Reply to HighlandExplorer

You're spot on about the aggressive protection logic in cold conditions. I've seen this crop up a fair bit on here. The thing is, Victron's BMS is actually behaving correctly – it's protecting your batteries from damage, which is the whole point.

That said, a few things worth checking:

Have you adjusted the low-temperature cut-off settings in your Victron config? You can raise the threshold a bit if you're regularly in sub-zero. Also, make sure your battery temperature sensor is actually working – sometimes they get disconnected and the BMS defaults to conservative settings.

What battery chemistry are you running? LiFePO₄ is typically safer in cold than other lithium types, but you're still limited on charging below about 0°C regardless.

Worth a chat with the Victron support crew too – they're usually helpful with tuning for Highland conditions.

Bloody hell, Scottish Highlands in winter and you're surprised the BMS is having a mood? Mine does the same thing in my motorhome when it drops below 5°C — Victron's just being protective, the paranoid sods. Check your settings in VictronConnect; there's usually a temperature compensation curve you can tweak. Had to dial mine back from the factory settings or I'd be sat in the dark every other week. Also make sure your batteries are actually rated for those conditions — if you've gone cheap, well, you've earned this. What capacity pack are you running?

Reply to HighlandExplorer

Cold weather BMS cutouts are frustrating, but there's usually something you can tweak. A few things worth checking:

First, what temperature are you actually hitting? Victron's protection kicks in around 0°C for charging, which is quite conservative. If you're confident your batteries can handle it, you might adjust the low-temp threshold in the settings—though I'd be cautious about pushing this too far.

More importantly, check your cell balancing and internal resistance. Cold makes batteries sluggish, so a weak cell can trigger protection faster than you'd expect. Also ensure your BMS is reading accurate temps—a faulty sensor can cause phantom cutouts.

@Zoe1993 and @RetiredNurse49 are right about the aggression, but it's usually there for good reason. What battery chemistry are you running? That'll affect how much headroom you've got.

Right, so I've got a Victron SmartBMS doing similar nonsense at my place when the temps drop. The trick I found is actually in the settings—there's a cold weather threshold buried in the advanced config that most people miss entirely.

@HighlandExplorer, have you checked if yours is set to the factory default? Mine was basically program

Reply to HighlandExplorer

Cold weather can definitely throw a spanner in the works with Victron gear. Beyond the usual suspect of cell balancing issues that @EllaPalmer mentioned, have you checked your BMS temperature sensor placement? If it's reading ambient rather than actual battery temp, you might be getting false low-temp shutdowns.

Worth also verifying your BMS firmware is up to date – Victron's pushed out a few updates specifically addressing cold-weather protection logic over the past couple years.

One thing I'd specifically check: is your battery actually dropping below the configured cutoff, or is the BMS being overly cautious? You can adjust those thresholds in the settings if you're confident your cells can handle it. Just go steady with it.

How low are we talking temperature-wise in your setup?

Had this exact grief last February in my tiny house build. Worth checking your low temperature charge disconnect threshold in the BMS settings — Victron ships these quite conservative from factory. Mine was cutting at 5°C when Fogstar actually rate their LiFePO4 cells down to 0°C for charging.

Also worth noting: if you're running any resistive heating near the battery bank, make sure it's not creating a localised hot spot that confuses the temperature sensor reading. Had a bizarre intermittent fault traced back to exactly that.

One thing @MoorLee and others haven't mentioned — check your VE.Bus system logs via VictronConnect. The BMS cutout events are timestamped and you can correlate them against ambient temperature data. Took me ages to realise my cutouts were consistently happening at 0300 when the hut got coldest, not randomly as I'd assumed.

Great thread, this. @HighlandExplorer, one thing I'd add that hasn't been mentioned yet — check whether your battery temperature sensor is actually making solid contact with the cell surface. Mine was barely touching after some vibration from the wind, giving the BMS a false reading a good 4-5°C warmer than actual cell temp. Wrapped it properly with some self-amalgamating tape and the spurious cutouts stopped almost immediately. Cheap fix before diving into threshold settings. Worth ruling out before anything else really.

@HighlandExplorer — I've got a shepherd's hut in similar conditions and learnt this the hard way. Check your battery temperature sensor placement. If it's clipped to the bus bar rather than directly on a cell, you'll get readings 3-4°C warmer than actual cell temperature during cold nights, meaning the BMS thinks cells are warmer than they are right up until it disconnects unexpectedly.

Fogstar cells in particular seem sensitive to this. Moved my sensor, problem essentially vanished.

Also worth reviewing whether your Cerbo GX firmware is current — there was a known interaction with SmartBMS low-temp logic in older builds.