Storm season prep — emergency power checklist

Right, after the last storm knocked out power for three days whilst I was parked up in the Lake District, I've learned a thing or two about not becoming a human popsicle.

The essentials I won't budge on:

• Battery bank with decent capacity — I've got a 10kWh LiFePO₄ setup (Victron LiFePO₄ Smart) that'll actually keep the basics running. Learned the hard way that "enough" means more than you think.
• Redundancy — solar panels are useless when it's pissing down for a week. I've got a small petrol generator tucked away purely for charging batteries when the clouds move in permanently.
• Inverter rated properly — undersizing here is a false economy. Mine's a 3kVA Victron because running everything at 80% capacity keeps it from melting during a flap.
• Loads actually sorted — no point having 10kWh if your immersion heater's going to drain it in an hour. Know what you're actually running.

The daft stuff I did wrong:

Neglected to label my battery isolator switch. In a panic during the storm, I couldn't find it. Embarrassing when you're trying to disconnect things safely.

What's your setup look like? Are you relying on mains backup, or going full island mode? Genuinely curious whether anyone's actually stress-tested their emergency rig during a proper outage, because the simulation in my head never matches reality.

Spot on about the lessons learned the hard way. Three days is rough going.

Worth adding to your list: a dedicated leisure battery monitor (I use a Victron BMV-712) so you're not guessing state of charge in the dark. Nothing worse than rationing power when you don't know where you actually stand. Paired with a quality DC-DC charger (Renogy or Victron), you can keep things topped up off the engine without flattening your starter battery.

Also consider a small petrol heater rather than relying solely on electric. Propex or Eberspächer units are brilliant but pricey — I've seen lads get by with a basic diesel heater (~£300) running off your tank. Keeps the van at liveable temps without hammering the battery.

Battery capacity itself — if you're regularly parked remote, 400Ah lithium genuinely changes the game compared to lead-acid. Worth the investment over a few seasons.

What capacity are you running currently?

@MarineGeoff three days sounds brutal. Question though — what capacity battery bank are you running now, and did it actually last the full three days or did you have to ration?

I'm in the middle of upgrading my van setup and wondering if I've been undersizing. Currently on 400Ah LiFePO4 but come winter I'm genuinely worried about grey skies hammering my solar input for days on end. Are you relying on anything else for top-ups — generator, shore power when you find it?

Also curious about your heating strategy. I've got a Victron MPPT that's brilliant when the sun cooperates, but the actual power draw from heating in Lake District conditions must've been mental. Did you end up running anything? Thinking about adding a diesel heater to take some load off the batteries rather than chasing every kWh from the sky.

I've been through similar on the boat during winter mooring season — nothing quite like realising your Victron setup's the difference between comfort and misery. Three days is genuinely testing.

What caught me out wasn't just capacity but discharge rate. I'd originally undersized my battery bank thinking I'd ration usage, but that meant running heating, lighting and water pump all contributed to faster drain. Swapped to a decent Lifepo4 setup which holds voltage better under load — made a huge difference psychologically too, knowing I had actual reserve.

One thing I'd add: test your backup heating before you need it. I discovered mid-November that my little diesel heater wasn't getting proper fuel draw because the line had split. Could've been catastrophic in a proper freeze-out.

Also keep spare fuses for your inverter in an accessible spot. Sounds daft but you don't want to be hunting through lockers when you're cold.

Blimey, three days is proper testing. I've got a garden office setup that nearly became a freezer box last February when we had that unexpected cold snap — my Victron MPPT was throttling down to nothing with the cloud cover, and I hadn't banked enough reserve capacity.

What saved me was realising I'd been too clever by half with my lithium setup. Swapped in a modest lead-acid backup (old school, I know) that doesn't sulk when it's cold like LiFePO4 can. Means I've got flexibility now — run the office off lithium when it's decent weather, fall back to the lead-acid when things get grim.

@MarineGeoff — honestly worth checking your battery chemistry, especially if you're relying on it during winter. And if you're planning any ev charging during poor weather, that's another beast entirely. Had to accept I can't do both simultaneously on overcast days.

The other thing nobody mentions: your battery monitor becomes your best mate. Knowing exactly what you've actually got versus what you think you've got is the difference between keeping warm and becoming a very

Mate, three days is no joke — glad you're sorting this properly. A few things that've made a real difference for me:

Thermal management is half the battle in winter outages. I've found that a decent wood burner or even a small diesel heater (if you've got the space) is worth its weight in gold when mains power's gone. Battery alone won't cut it for heating.

Redundancy is key too. Don't rely on just one power source. I run solar + a small petrol gen as backup, plus I keep a hefty leisure battery setup. That way if one system fails, I'm not completely stuffed.

@SueParker64 — how's your Victron holding up now? I'm curious whether you've added any monitoring to it since your winter issues.

Also worth mentioning: keep your battery bank somewhere you can actually access it easily during bad weather. Buried under kit or in difficult-to-reach spots is asking for trouble when you're stressed and freezing.

What capacity are you looking at running now after the Lake District experience?

The real killer during extended outages is battery temperature management, which nobody talks about enough. Lithium cells perform terribly below 0°C and lead-acid capacity drops by roughly 50% at freezing point—@MarineGeoff, if you're stationary for three days, you need to know your battery's actual usable capacity in winter conditions, not the marketing figure.

I've got a Fogstar LiFePO₄ setup in my van and learned the hard way that a cheap 500W immersion heater running off the battery during the day actually extends your range because the pack performs better warm. Counterintuitive but the maths work out. Cost me about £40 and honestly transformed winter reliability.

Also worth considering: a small petrol inverter-generator as backup isn't just about power—it's about charging your main battery bank efficiently when solar's hopeless. Your Victron charger will manage it properly rather than you running a kettle directly and flatting everything.

What's your current battery chemistry and capacity? Makes a massive difference to what actually makes sense for your setup.

Right, @MarineGeoff, three days is genuinely brutal. The thing everyone overlooks is thermal management during extended outages — your battery capacity plummets when it's cold, and you're fighting physics.

I've got a 5kWh LiFePO₄ bank in my tiny house setup, and during winter storms the usable capacity drops by nearly 40% if temps dip below 5°C. I've wrapped the battery box with XPS foam and installed a small 12V heater circuit that kicks in automatically — costs pennies to run but keeps chemistry working properly.

Also worth considering: a petrol generator isn't glamorous, but it's non-negotiable backup. I run a Honda EU22i (quiet enough not to upset neighbours) paired with a Victron MultiPlus for seamless switchover. During the February incident @LindaLamb mentioned, that hybrid setup kept my fridge running and batteries topped up.

For cabin heating specifically, a quality wood burner beats any electric solution during prolonged grid loss. You're not dependent on battery state of charge, and it's genuinely comforting.

Been thinking about this a lot since our static caravan setup got caught in that winter blow last year. Battery performance absolutely tanked in the cold — we're talking 40% capacity loss just from temperature drop.

What nobody mentions is the insulation side of things. We've wrapped our battery box with rockwool and a reflective layer, and it's made a massive difference. Even passive thermal mass helps — keeping a few litres of water near the batteries can buffer temperature swings.

Also worth considering: does your setup have a battery heater? We run a small 12V heating pad on our Victron system, kicks in automatically below 0°C. Costs peanuts to run but saves your chemistry.

One thing though — are you running lithium or lead-acid? Because the strategies differ quite a bit. Lead-acid is more forgiving in cold, but lithium needs that temperature management or the BMS will just cut you off mid-outage, which is exactly when you don't want it happening.

What's your current battery setup?

Been through this myself during a Welsh winter lockdown—motorhome, subzero temps, and a Victron LiFePO4 bank that went from 100% usable capacity to about 60% literally overnight. Brutal lesson.

What @FormerMechanic68 and @Titch are spot on about: lithium hates cold. Most people don't realise their fancy 48V system becomes a brick below 0°C. I've since fitted an immersion heater controlled by a basic thermostat—costs under £50 and keeps the battery enclosure at 5°C minimum. Game changer.

The other bit nobody mentions: your inverter efficiency tanks in cold weather too. A Victron Phoenix running in a freezing caravan might pull 30% more amperage than your summer calculations suggest. Plan for that.

For actual emergency prep, keep your high-drain devices (heating, water pump) on a separate sub-panel. Means you can ration power to essentials—heating + comms only—rather than killing your whole system because you wanted hot water.

Also: fully charge before the forecast

Had a similar nightmare in my shepherds hut two winters back when snow took the grid down for four days. The thing that saved me wasn't the battery capacity—it was recognising that once temperatures dropped below freezing, my lithium pack's usable capacity tanked hard.

What @SimonKelly mentioned about LiFePO4 performance in cold is spot on. I learned to keep mine in an insulated box with a basic heating pad (12V Victron setup running off a small auxiliary battery). Cost about £40 and made the difference between having power and watching my Fogstar inverter cut out repeatedly.

The overlooked bit though: your water system becomes critical when you've got no mains. I switched to carrying extra jerry cans and insulating pipes with pipe lagging. Dead simple, but plumbing freezing solid means you're cooking on a camping stove anyway.

For the motorhome crowd especially—a small diesel heater (like an Espar) pays for itself in comfort and battery longevity. Takes the thermal load off your electrics entirely. I've got one earmarked for the next build.

@MarineGeoff - good timing on this. The Lake District in winter is no joke, and three days without power in a vehicle is a proper ordeal.

One thing I'd add that doesn't get mentioned enough: thermal mass matters more than you'd think. Before a storm hits, charge your battery bank to full, run your heating, and get everything warm—walls, furniture, water tanks. That stored heat buys you critical hours when the power goes down, especially if you're stuck and can't move around much.

Also worth noting—if you're relying on solar during winter storms, you're essentially counting on nothing. I'd recommend sizing your battery capacity assuming zero generation for at least 48 hours. Better to overspec and feel smug than ration heat in a Lake District blizzard.

@SimonKelly mentioned your LiFePO4 shutting down in the cold—did you end up adding a battery heater? Makes a massive difference. I've got a simple 150W immersion heater controlled by a thermostat on mine now. Costs pennies to run but keeps the batteries functional when temperatures drop.

Three days in a van without heating is basically method acting for a penguin, mate. The real wake-up call for me was realising my 100Ah Fogstar lithium wouldn't keep the cab heater running past hour two—turns out you need either a proper sized bank or the ability to tolerate your own breath crystallising.

Key thing nobody mentions: keep a cheap petrol heater as backup (properly vented, obviously—don't want to become a carbon monoxide statistic). Your battery might be rated for -20°C, but good luck getting useful amps out of it when it's actually that cold. I now run mine with a blanket and keep the charge above 40% during winter storms.

Also chuck in a proper 12V kettle and some thermal waterproofs—you'd be amazed how much heat a cuppa and moving around actually generates compared to just sat shivering hoping your LiFePO4 survives the cold.

@SimonKelly—did yours recover okay when it warmed up? Mine needed a full reset after a particularly brutal night.

Been there with the van heating nightmare. Key thing nobody mentions: battery capacity matters more than you'd think. A decent lithium setup (I'm running 200Ah LiFePO4) plus a small inverter means you can run a 1kW heater for hours without draining to danger levels. Pair it with solar and you're golden even on grey days. Insulation's crucial too—thermal blinds made more difference than my beefed-up battery, honestly.

@MarineGaz nailed it. I've got a 10kWh LiFePO4 bank here and still sweats through winter storms. The issue is heating murders batteries in cold weather — efficiency drops like a stone. Victron's BMS helps manage it, but honestly, a backup petrol heater (even a cheap one) pays for itself in peace of mind. Learned that the hard way last February.