Anyone else had their BMS cut out mid-storm when they needed it most?

Last October I was three days into a proper howling Welsh weekend — no mains, no signal, wind rattling the shed something rotten — and my Fogstar Drift 100Ah LiFePO4 just... went dark. Dead quiet. The BMS had tripped on what I later worked out was a low-temp cutoff. Ambient had dropped to around 4°C overnight and I hadn't even thought about the cold threshold on that unit. Generator wouldn't start either. Genuinely grim few hours.

I've since added a Victron BMV-712 to keep a proper eye on things and set up a low-temp alarm, but I'm still not 100% sure I've got the right protection layers in place for winter. My setup is fairly modest — 200W of panels, the single 100Ah Drift, and a Victron Phoenix 375VA inverter running the essentials (router, lighting, a small pump).

What's the community's approach to cold-weather BMS protection in the UK? Are you relying purely on the built-in BMS thresholds, adding external heating mats, or doing something else entirely? Curious whether anyone's actually tested their low-temp charge cutoff in anger rather than just trusting the spec sheet.

@KevLee had almost exactly this happen at the static van last winter. Turned out my BMS was tripping on low temperature cutoff — cells dropped below the protection threshold overnight and that was that. LiFePO4 really doesn't like charging below about 5°C, and the BMS was doing its job, just at the worst possible moment.

Worth checking whether it was a temp cutoff or an overcurrent event — most BMS units log the fault reason if you can pull data from them.

My fix was wrapping the battery compartment with a small self-regulating heat tape on a thermostat. Draws next to nothing but keeps the cells above the danger zone. Running Victron kit here which at least gives you proper fault alerts rather than just going silent in the dark.

@KevLee gutting timing. Had something similar with my garden office setup — battery just dropped off during a cold snap last January.

Worth checking if your Fogstar has a low temp charge cutoff kicking in. Mine was tripping because the LiFePO4 cells genuinely shouldn't be charged below around 0°C — it's a protection feature, not a fault as such.

Fix for me was a simple self-regulating heat mat under the battery, runs off a tiny bit of the bank itself. Sorted it completely.

Also worth logging the BMS data beforehand if you can — the Victron app shows this nicely if you've got a SmartShunt in the mix. Pinpoints exactly what triggered the cutout rather than guessing.

@KevLee seen this exact scenario. My Fogstar did something similar last winter — turned out the cell voltage imbalance had been quietly building for weeks and the storm conditions just pushed it over the edge. BMS did its job, basically.

Worth pulling the logs if your BMS supports it. Check for:

• Cell delta voltage at point of cutout
• Low temp cutoff (as @OldSailor79 flagged)
• Overcurrent from a surge load

Mine recovered fine once I equalised the cells and let it warm up a bit. If it's not coming back at all though, could be something more serious — what's it reading on the Victron app if you've got one connected?