Anyone else had their BMS cut out in cold weather? Fogstar Drift 100Ah doing my head in

Had a frustrating weekend with my garden office setup. Temps dropped to about 3°C overnight and my Fogstar Drift 100Ah just shut itself off — BMS low temperature protection kicking in, I assume. Victron MPPT and BMV-712 both showing the battery had gone offline completely. Took until mid-morning for it to warm up enough to reconnect.

The cabinet the battery sits in isn't insulated at all at the moment. Wondering if that's the real culprit — ambient just getting too low — or whether Fogstar's low-temp cutoff threshold is set aggressively compared to other LiFePO4 options on the market.

Has anyone wrapped their batteries in insulation or added a small heat mat to keep temps above the cutoff? What's a reasonable minimum enclosure temp to aim for? I've seen some people mention 5°C as the safe charging floor for LiFePO4 but wasn't sure if discharge is also affected at that sort of temperature.

@CliffWill had almost exactly this with my motorhome last February, parked up in the Brecon Beacons when overnight temps absolutely plummeted.

The thing nobody tells you upfront is that LiFePO4 can't accept charge below roughly 5°C without risking lithium plating — the BMS is genuinely protecting the cells, not just being awkward. The Drift's cutoff is doing its job.

What sorted it for me was wrapping the battery in a small self-regulating heat mat (the kind sold for pipe frost protection) connected to a simple thermostat controller. Keeps the battery above the threshold without cooking anything.

Longer term, insulating the battery compartment properly made a massive difference — thermal mass holds residual heat from daytime charging surprisingly well.

Worth checking whether your discharge still works at 3°C even if charge is cut — most Fogstar units allow that.

@CliffWill yeah the Drift's low temp cutoff is around 5°C for charging if I remember right — it's a lithium thing, not a Fogstar fault as such. Charging below that damages the cells.

Worth looking at whether you can add a small heat mat under the battery, that's what I've done in my motorhome. Decent 12v ones on Amazon for a tenner. Keep the battery in an insulated box and it holds temp surprisingly well overnight even when ambient drops.

Alternatively a Victron MPPT can be configured to stop charge at a set temp if you've got a temp sensor attached — stops the BMS having to do the hard work.

Hey @CliffWill, gutting timing with the garden office! Worth clarifying though — the low temp protection should only block charging below that threshold, not discharging. So if your BMS shut off completely, it might be worth checking whether your solar/charger was attempting to push charge into it overnight and the BMS tripped as a result. As @Clive1999 says, around 5°C is typical for LiFePO4.

A practical fix is adding a small self-regulating heat mat (the reptile tank type work a treat) inside your battery enclosure, wired to come on via a thermostat. Keeps it just above the cutoff threshold without using much power. Alternatively, better insulating the enclosure itself makes a big difference — a well-insulated box retains residual heat from the cells quite well overnight. What's your battery housing situation at the moment?

@CliffWill worth checking whether it actually cut out completely or just blocked charging — as @Steve2000 hints at, those are two different scenarios. If your loads were still running fine but the solar/charger stopped feeding in, that's the BMS doing exactly what it should. LiFePO4 cells can be genuinely damaged by charging below around 5°C, so it's a feature rather than a fault.

Practical fix for your garden office: a small self-regulating heat tape wrapped around the battery, or even just a bit of closed-cell foam insulation around the case, can keep temps above the threshold on cold nights without much energy overhead. Some people run a tiny thermostatically controlled pad heater off a small lead-acid buffer for exactly this purpose.

What's your current battery enclosure situation — is it exposed to outside air or in an insulated box?