Can I charge LiFePO4 below freezing?

Original Post

Right, so I'm planning to wild camp in Scotland over winter in the van and I've got a shiny new 200Ah LiFePO4 battery from Fogstar sitting in the back. Currently running a Victron MPPT 100/30 and a Renogy 400W solar panel, but I'm a bit concerned about charging when it's brass monkeys outside.

I know LiFePO4 are generally hardier than lead-acid, but I'm seeing conflicting info online — some say you can charge down to -20°C, others reckon you'll brick the cells if you go below 0°C. My BMS has built-in low-temp protection, so it supposedly cuts off charging when things get dodgy, but I'm wondering if that's actually reliable or if I'm about to become an expensive cautionary tale on the forum.

The van's got a bit of insulation and I'm planning to heat the battery compartment with a small 12V heater when temps drop, but I want to know if that's overkill or essential.

My questions:

• What's the actual minimum temp for safe charging?
• Will the BMS protection work reliably, or should I supplement it?
• Is the heating approach sensible or am I overthinking this?

Cheers in advance — don't fancy explaining to my missus how I've turned a grand's worth of lithium into an expensive paperweight.

Mate, your Fogstar won't charge below 0°C — it's got a BMS that'll lock you out faster than a Scottish landowner spotting a campervan on their land.

Need to keep that 200Ah warm somehow. Battery blanket, insulation box with a heat source, or just accept you're pulling from stored energy only until spring thaw. Some folk use a small 12V heater pad wired to trigger around freezing, but honestly in a van that's more faff than it's worth.

Your Victron M will tell you straight up when it refuses — very Australian of it, that.

Aye, @NotAnElectrician80's right on that one. LiFePO4's a bit fussy in the cold — most BMS units won't let you charge below 0°C, and your Fogstar will be no exception. Lithium plating risk and all that.

What you can do: keep the battery insulated in the van, maybe a decent blanket or foil emergency wrap round it. The discharge side's fine down to -20°C or so, but charging's the sticky bit.

If you're running solar + alternator charging, you might struggle on gloomy Scottish winter days anyway. Worth considering a small 230V heater pad on a thermostat if you're genuinely off-grid for weeks — some folk use a cheapo heated blanket on a timer.

What's your current charging setup? That'll determine your options better.

Been wrestling with this myself on my garden office setup over winter. The issue isn't really the chemistry — LiFePO4 can handle cold discharge fine — it's the charging that causes lithium plating inside the cells, which degrades them permanently.

Your Fogstar's BMS will cut you off, but the real question is: what's your actual use case? If you're wild camping and mostly discharging (lights, heating, laptop), you're probably okay. It's the charging in sub-zero that's the problem.

Worth checking if you can heat the battery enclosure passively — even a bit of insulation and maybe a small heat mat tied to your alternator charging can make a difference. Some people wire up a simple thermostat-controlled heater, though that's a rabbit hole of complexity.

What's your charging source going to be — solar, alternator, or mains?

Not sure if your Fogstar manual specifies it, but most LiFePO4 BMS units lock charging below 0°C — that's the frustrating reality. The chemistry itself can technically handle it, but lithium plating becomes a risk and manufacturers aren't having it.

What I've done with my static caravan setup is keep the battery in an insulated box with a low-watt heating pad running off the alternator when driving. Costs pennies but keeps things above 5°C minimum. For wild camping though, that's trickier.

If you're serious about winter Scottish trips, you might look at a battery heater blanket — Victron make one and it integrates with your M (guessing Multiplus?). Not cheap but beats being stuck with a locked BMS when you need power most.

How cold are we talking — regular Scottish winter or full arctic conditions?

Have you checked what temperature threshold your Fogstar's BMS actually has? Mine's set to 5°C, which is annoying but manageable in a van situation.

The workaround I've been tinkering with is wrapping the battery in decent insulation — I used some XPS foam boards around mine. Keeps the ambient cold from bleeding heat straight out of the pack. Combined with a small heating pad on a timer (running off solar during the day), you can keep it above the charging threshold without burning loads of energy.

That said, if you're wild camping in Scotland regularly, might be worth looking at whether you actually need to charge while stationary in freezing temps? I tend to do most charging on drive days when the engine heat naturally warms things up. Just a thought depending on your usage pattern.

Wild camping in Scotland sounds brilliant, though the battery situation's a bit grim in winter. @BayJason's spot on about the BMS lockout—it's a protective measure that's genuinely necessary, not just manufacturers being awkward.

The real trick is understanding why it matters. Lithium ions move sluggishly when cold, and if you force charging below freezing, you get lithium plating on the anode. That's permanent damage, potentially dangerous, and no amount of warming it up afterwards fixes it.

What I've done with my shepherd's hut setup is insulation and passive heating. Keep that Fogstar wrapped in a thermal blanket when it's not in use—even a decent sleeping bag works. If you're running a heater in the van anyway, that ambient warmth helps enormously. On my winter trips, I've found that keeping the battery at 5-10°C through insulation means I can charge once the morning sun hits or I'm running the engine.

Bring a second smaller LiFePO4 indoors for critical loads if you need that security blanket.

The BMS cutoff is the real blocker here. Most LiFePO4 cells suffer lithium plating when charged below 0°C—it's not just manufacturers being cautious. Fogstar's threshold is typically 5°C, though worth confirming yours specifically.

Your options are limited but workable:

Battery heater — A 200W immersion heater inside the battery enclosure can maintain 5°C+ passively. Victron's battery heaters integrate cleanly with their systems and draw minimal power when idle.

Insulation strategy — Wrap the battery in rockwool or reflective wrap. Thermal mass helps—even a few litres of water nearby radiates heat overnight.

Charge timing — Pop into a pub or café during daylight when van temperatures peak, then rely on nightly heating to maintain threshold.

Real talk: Scotland in winter means the battery won't deliver rated capacity anyway due to cold cell resistance. If you're relying on evening heating/lighting, you'll want a secondary smaller LiFePO4 kept indoors for critical loads.

What's your actual power draw? Might inform whether accepting reduced winter capacity is feasible.

The BMS cutoff is frustrating but it's there for good reason — lithium plating degrades the cells permanently. That said, there are workarounds if you're keen on winter camping.

I've got a Fogstar 200Ah myself and the BMS does cut at 5°C. Some folk use a battery blanket or heated enclosure, but honestly for a van that's added complexity. What I've found more practical: charge during the warmer part of the day (even Scottish winter has a few hours mid-afternoon), or if you're stationary, position the battery where it catches whatever sun's available.

If you're running an inverter anyway, you could also trickle a small heating element — just don't overdo it or your battery management becomes a full-time job. Some people mount their batteries in an insulated box with passive thermal mass (water bottles, etc.) which helps stabilise temperature swings.

Worth checking whether your Victron charger has temperature compensation settings too. Might give you a degree or two of wiggle room, though won't override the BMS entirely.

What's your charging source — solar, hookup

The Fogstar manual should specify your exact cutoff temp, but most LiFePO4 BMS systems won't let you charge below 0°C—and honestly, that's the right call. Lithium plating is permanent damage you can't reverse.

What actually works for winter van life: insulation. I've got mine wrapped in a decent blanket setup in the boat (not quite Scottish winter, but gets nippy enough). Even basic thermal mass around the battery helps—keeps ambient swings from translating directly to cell temp. A heated battery box isn't overkill if you're serious about wild camping up there.

The other option is accept that winter charging comes from the alternator or a small solar panel on sunny days, then rely on discharge cycles to keep the battery warm. Discharging generates heat, so if you're running 12V systems through the day, the battery stays higher than air temp naturally.

Don't fight the BMS cutoff. Work around it instead. Your Victron should have decent monitoring—check actual cell temps rather than relying on ambient readings.

Have you checked what cutoff temp your Fogstar BMS is actually set to? Some of the newer models have slightly higher thresholds than the standard 0°C, though you'll want to verify against your specific unit's documentation.

The bigger practical question for Scottish winter wild camping: are you planning to keep the battery itself warm somehow? Even if you could override the BMS cutoff (which I wouldn't recommend), the chemistry still suffers below freezing. Most people running winter setups either insulate the battery box heavily or use a low-power heating mat controlled by a thermostat—can add maybe 50-100W when temps drop.

What's your current power draw like? Might be worth looking at whether you can just accept slower charging during winter months and prioritise charging during daylight hours when ambient temps are higher. Also curious whether your van's got decent insulation—that'll make more difference than you'd think.

The BMS cutoff is absolutely the limiting factor here, and @LazyNomad's right about checking your manual first. That said, there's a practical workaround I've used with my own Fogstar 280Ah in the shepherd's hut during winter—it gets properly cold.

The charge controller (guessing you've got a Victron MPPT?) can be configured to stop sending current when temps drop, but your BMS will cut it anyway if you're below threshold. What actually works is passive battery warming. I've had success with a simple 12V heating pad wrapped round the battery under insulation—not high wattage, just 20-30W to keep it above 0°C during charging windows. Costs bugger all and extends your usable window considerably.

The lithium plating risk @BayJason mentioned is real, but it's specifically about charging below freezing. Discharging in cold is fine. So if you're wild camping, you can discharge all day, then charge only during the warmer afternoon hours or when the van's being used for heating anyway.

Winter Scottish camping in a van with

The BMS cutoff is indeed your hard limit here, but there's a practical workaround worth considering if you're serious about Scottish winter camping.

Your Fogstar's BMS will likely cut charging around 0°C, which is frustrating but exists for good reason—lithium plating on the anode during sub-zero charging can permanently damage the cells. That said, you can physically warm the battery temporarily to enable charging.

I've had decent results wrapping my 280Ah LiFePO4 with self-adhesive foam pipe insulation during winter trips. Pair that with a small 12V heating pad (around 50W) and you can nudge the pack above freezing without draining much energy. Some folk use the van's cab heater if the battery's close enough, though you'll want to monitor temperatures with a simple digital thermometer.

Better yet, charge opportunistically during daylight when ambient temps are highest, and size your solar array or portable charger to take advantage of those windows. If you're regularly below 5°C, consider whether a smaller lead-acid auxiliary battery for critical loads might reduce dependency on the LiFePO4 during the coldest periods.

What's your current charge source—solar, vehicle alternator, or mains?

Mate, I've been down this road with my boat battery setup and it's a proper minefield. The Fogstar manual should specify the exact cutoff temp — mine's set to 0°C which is frustratingly conservative for Scottish winter camping.

Here's what I've actually done: insulation. Wrapped my battery box with 50mm XPS foam and tucked a small 12V heating pad inside (just 20W, barely draws anything). Keeps the pack sitting around 5-10°C even in proper cold conditions. Cost about £40 total.

The BMS won't let you charge below its threshold regardless, so fighting that is pointless. But preventing the battery dropping below that threshold in the first place changes everything. I've also noticed my charge acceptance improves when the pack isn't stone cold — quicker bulk charging on those brief sunny winter days.

Scottish winter's going to be grim for solar anyway, so focus your effort on managing what heat you've got rather than trying to bypass the BMS. Your Victron's probably your biggest heat source if you're running a charger — position the battery near that if you can.

The Fogstar 200Ah specs a charging cutoff around 0°C, which your BMS will enforce—no getting round that without disabling it, which you absolutely shouldn't do. Lithium plating becomes a genuine risk below freezing, and that's permanent damage.

What's worth exploring instead: thermal management. I've got a similar setup in my static caravan and use a basic stick heater on a thermostat in the battery enclosure during winter months. Cost's negligible compared to replacing a £3k+ battery pack. Even passive insulation helps—wrapping the battery box with old duvets or rockwool keeps residual heat trapped longer.

For wild camping specifically, your charging pattern matters. Daytime solar will warm the cells naturally; if you're running a generator or DC charger, you're generating heat anyway. The real issue comes with sustained cold and low state of charge—that's when the BMS gets nervous.

Check your actual Fogstar manual for the precise cutoff temperature. Some newer batches have slightly different specs. And @Lefty72, what's your charging source? That'll change the practical approach considerably.