Anyone else running Fogstar Drift LiFePO4 in a shepherd's hut setup? Curious about BMS behaviour in cold

Been running a 200Ah Fogstar Drift in my shepherd's hut for about eight months now. Generally dead happy with it — pairs nicely with my Victron SmartSolar and the Bluetooth monitoring via the Victron app is solid. But I've noticed the BMS cutting charge when overnight temps drop below around 4°C, which I assume is the low-temp protection kicking in.

Not complaining exactly — that's the BMS doing its job. But it means on cold mornings the battery won't accept charge from the panels until things warm up a bit, sometimes not until 10–11am. In a hut that's occupied most of the time that's fine, but I've got a small EV charger setup (a basic 3.6kW unit) drawing from the system and the timing is starting to matter more.

Has anyone found a workaround? I've seen some folk mention wrapping cells in self-regulating heat tape on a separate small lead-acid or supercap buffer, but that feels like a lot of faff. Wondering if the newer Drift batts have revised the low-temp cutoff threshold, or whether a different BMS entirely is worth looking at.

EwanMorris76 | 847 posts | ⭐ Trusted Contributor

@NeilBurns91 Great setup! The Drift's low-temp cutoff is worth keeping an eye on — from what I've seen it starts getting cautious around 5°C charging and will shut off charge completely below 0°C, which is pretty standard LiFePO4 behaviour but can catch you out in an uninsulated hut during a cold snap.

A couple of things that helped me: I've got a small thermostatically controlled heat mat tucked against my battery bank, draws barely anything overnight. Also worth checking your Victron charge profile — make sure you're not pushing absorption voltage too hard in winter.

Have you noticed any self-discharge issues sitting idle between visits? That's where I find shepherd's hut setups differ from permanent installs. The Drift holds reasonably well in my experience but curious what yours is doing over longer gaps.

Frank1999 | 312 posts | ⭐ Regular

@NeilBurns91 Worth knowing that the Drift's BMS will disconnect charging below around 0°C to protect the cells — perfectly normal behaviour, not a fault. If your hut drops below freezing overnight, you might find the battery won't accept charge first thing in the morning until it warms up a bit.

In a shepherd's hut this can catch people out when they're expecting the solar to crack on at dawn but nothing's happening. A small self-heating mat underneath the battery helps enormously through winter — some folk use a basic thermostat-controlled seedling mat. Discharge should still work fine in the cold though, so you won't lose lighting or heating overnight. Just the charge acceptance that gets restricted. Has it actually triggered for you yet or are you just anticipating potential issues?

IslandCruiser | 203 posts

Had something similar last winter in my static — woke up to find the Fogstar had cut charging overnight when temps dropped sharply. BMS doing its job but caught me off guard the first time.

Worth setting a low-temp charge cutoff in your Victron SmartSolar to pre-empt the BMS rather than letting the BMS itself do the hard disconnect repeatedly. Better for battery longevity apparently.

Also if your hut isn't insulated brilliantly, tucking the battery somewhere it benefits from residual heat makes a real difference — mine lives in an internal cupboard now rather than an external locker and rarely drops low enough to trigger anything.

@Frank1999 and @EwanMorris76 have covered the cutoff side well — just adding that managing it from the Victron side feels cleaner than relying solely on BMS protection.

DodgyHermit | 156 posts | Shepherd's Hut Dweller

Running a similar setup in my hut — Drift paired with a Victron SmartSolar MPPT 100/30. What the others haven't mentioned is that the discharge side behaves differently to charging in the cold. My BMS hasn't cut discharge at low temps, only charging, so I've still had lighting and basic loads running on those frosty mornings even when charge was locked out.

Practical fix that worked for me: I've got a small 12v heat mat tucked against the battery casing, triggered by a simple temperature switch around 3°C. Draws barely anything and keeps the BMS happy enough to accept charge by mid-morning once the solar picks up.

Worth checking your Victron app — you can actually see exactly when charge disconnected overnight from the history graphs. Helped me pinpoint the exact threshold mine cuts at.