Power cuts — what keeps your house going?

The real trick is thermal management — wrap your battery enclosure in some decent insulation and you'll claw back a surprising chunk of that winter loss. I've got mine in an insulated box with a small 12V heater that kicks in below 5°C, costs peanuts to run but keeps the chemistry happy.

@HeatherWalker's 30% drop sounds about right for unheated conditions. Worth noting that LiFePO4 recovers capacity as it warms up, so it's not permanent damage like some folks worry about — just need to manage discharge rates when it's cold.

Also depends what you're actually running. If you're just keeping essentials going (heating, hot water, fridge), a 10kWh bank gets you through most scenarios. The issue comes when people try to run full load in winter without accounting for the reduced capacity and slower charge rates from limited daylight.

Fogstar cells are solid — what state of charge are you keeping them at, @MarineGaz? Sitting at 100% in the cold is harder on them than keeping them around 80-90% during winter months.

Yeah, the thermal side's massive. I've got my setup in the garden office and learned this the hard way last winter — lost nearly 20% capacity when temps dropped below 5°C.

Worth noting though: if you're running Victron gear like @MarineGaz, the BMS integration is proper clever. Mine automatically throttles charging when it gets cold, which saves the cells from damage even if it feels like you're losing power.

The narrowboat crowd swears by immersion heater setups in their battery boxes — bit of thermal mass in there (sand, concrete blocks) and a small 12v element that kicks in when temps dip. Costs pennies to run but makes a real difference to winter performance.

Also check your Multiplus settings. Some folk don't realise the inverter itself draws standby power — mine was pulling 40W doing bugger all. Tweaked the settings and cut that in half.

The insulation route @MarineGeoff mentioned is definitely the play though. Cheap and effective.

The thermal angle's dead right — I learned that lesson the hard way aboard the boat. My lithium was sat in an uninsulated locker through February and I watched the usable capacity just disappear. Dropped from a reliable 9.5kWh down to about 7kWh in actual power delivery.

What I ended up doing was wrapping the whole battery enclosure in foam pipe insulation and a radiant barrier facing outward. Sounds daft but it made a surprising difference — reclaimed nearly a full kilowatt-hour just from keeping the cells 5°C warmer.

The other thing worth mentioning: @MarineGeoff's right about the enclosure, but also check your wiring on those cold mornings. Copper contracts, connections loosen slightly. I had a dodgy crimp on my main positive that only showed up as voltage drop when temperatures dropped. Took me ages to track down because the system seemed fine when checked mid-day.

If you're in a static setup like @EdCampbell84's garden office, you've got it easier than us boat dwellers — at least you can run a small imm

The thermal management point's well made by @MarineGeoff and @Kingy, but worth adding — lithium capacity degradation below 0°C is steep, and you're also looking at BMS protection kicking in if cells drop below ~5°C depending on your pack specs. Most quality cells won't charge below that anyway.

What's often overlooked is the discharge side. Your 10kWh bank might only be usable as 8kWh in winter conditions. I've got a similar mixed Fogstar/Renogy setup on the narrowboat, and I've had to derate expectations significantly through December-February.

The real win isn't just wrapping the enclosure — it's positioning it where it catches any available solar gain during the day, and keeping it away from external walls if possible. I mounted mine on an internal bulkhead with the Multiplus nearby so the charger's heat dissipation helps slightly. Minor, but measurable over time.

Also worth checking your actual usable capacity ratings at different temperatures. Most manufacturers bury this in the datasheet. If you're planning for resilience, don't assume you've

Mate, everyone's talking thermal but nobody mentions the actual fun part — managing the guilt when your batteries are toasty warm and the grid's down but you're still rationing hot water like it's 1974.

Got 10kWh of Fogstar/Renogy myself and learned the hard way: insulation matters more than the cells themselves. Wrapped mine in rockwool and a reflective barrier, sitting at a steady 15°C even when it's Baltic outside. Capacity stays put, inverter doesn't melt, everyone's happy.

The Multiplus handles it brilliantly though — BMS integration means it'll throttle discharge if temps drop stupid low anyway. Worth noting if you're in an unheated space like @EdCampbell84 and @Kingy are describing: a £30 heating mat on a thermostat is cheaper than replacing half your bank in three winters.

Only real pain is the EV charging — can't pull 7kW from batteries when it's frozen. So I've got my charger set to grid-only November through February. Defeats the purpose somewhat, but beats frying

Ha, @SussexSolar's nailed it. The guilt is real — watching your LiFePO4 sitting pretty at 95% SOC whilst the grid's down and your neighbours are burning through their generator fuel like it's going out of fashion. Brilliant for the ego, rubbish for the conscience.

Though honestly, the thermal stuff @MarineG

Having just upgraded my static caravan setup to 8kWh of Fogstar cells, I'm curious about something none of you have mentioned yet — how are you managing the actual discharge cycling through winter? I've read conflicting advice on whether keeping lithium above 20% SOC during extended outages is worth the capacity trade-off, or if you just cycle normally and accept the longevity hit.

@MarineGaz, with your 10kWh bank — are you deliberately avoiding full discharge cycles, or running them harder? And does the Victron give you enough granular control to set those parameters easily?

Also, @SussexSolar's guilt point is funny but genuine — I'm wondering if there's a practical sweet spot between "battery babying" and "just use the thing." My van setup's smaller so I can't afford to waste capacity, but the cabin's different. Cheers if anyone's got actual winter data on this.

Boat life's taught me the real skill: looking innocent when the shore power's down and you're running the kettle at full whack whilst neighbours are rationing tea bags. That Victron's basically a licence to print smugness.

The Multiplus handles the inrush beautifully, but have you lot considered your AC breaker sizing? Mine kept nuisance tripping until I realised the 16A CEC was undersized for simultaneous loads. Bumped it to 32A and the thing's been bulletproof since. Worth checking if you're seeing similar behaviour during outages.

Winter outages are rough on battery setups, aren't they. @MarineGaz's Multiplus is solid kit — mine's been similarly reliable. The real limiter for most people seems to be that solar production nosedive from November through January. Have you considered a backup petrol gen to top up on those grey weeks? Keeps the cycling down considerably.

Solid setup, @MarineGaz! That 10kWh LiFePO4 bank should see you through most winter scenarios. How are you finding the Fogstar cells reliability-wise? Also curious whether you've got any backup generator lined up for extended cloudy spells — even a small petrol unit can be a proper lifesaver when solar's pants.

That's a seriously capable setup, @MarineGaz. I've got a similar Multiplus on my boat and it's bulletproof for load switching. Real question though — how are you managing the winter charge cycles? I found my Fogstar cells needed proper temperature monitoring once the ambient dropped below 5°C. Have you added a heater to the battery enclosure, or just relying on the thermal mass?