Grid's just gone down in my area - how long will my battery bank last with essentials only?

Mate, rough timing. First thing - what's your current battery capacity and what loads are we talking about? That'll determine everything.

I'm running 10kWh of LiFePO4 here and when I've tested essentials-only mode (fridge, freezer, lighting, comms), I can stretch it about 4-5 days depending on weather. Obviously solar during the day helps massively - even cloudy conditions give you something to work with.

Key things I'd focus on right now:

Load management - Kill anything non-essential. That second freezer, the water heater, constant chargers. Every watt counts.

Inverter efficiency - Most drop 10-15% efficiency at partial loads, so if your battery's showing 70% charge, you're not getting 70% of the rated capacity in real terms.

Temperature - Cold weather reduces battery output. If it's winter, expect about 10-15% less capacity than the specs suggest.

Monitoring - Get your Victron display or whatever monitoring you've got pulling live data. Real numbers beat guesswork when you're rationing power.

Honestly though, if this is an unplanned outage and you don't know the timescale, have you got any way to charge up? Genset, solar, even a mate's vehicle with an inverter? The grid usually comes back within 24-48 hours for most outages, but being prepared is different from gambling on it.

What's your setup looking like? Battery chemistry, inverter size, and roughly how many kWh are we working with? Might be able to give more specific advice.

Depends massively on what "essentials" means to you, doesn't it? I've got 15kWh in my tiny house setup and honestly, if I'm just running lights, fridge, and a kettle for tea, I can stretch it ages. But the moment someone mentions the immersion heater or the caravan's heating system kicks in, that battery gauge drops faster than my interest in winter camping.

Real talk though — I'd grab a Kill-a-Watt meter and actually measure what your essentials pull for a day. Most people massively underestimate phantom loads and how much the fridge costs them. My Victron system gives me the breakdown and it's genuinely eye-opening.

What kit have you got? Knowing your battery chemistry and inverter specs would help work out realistic numbers rather than just doom-scrolling power cuts online.

Narrowboat living's taught me that "essentials" is a funny thing — turns out you don't actually need the kettle, the toaster, and the shower running simultaneously, who knew?

Real talk though: if you're running fridge, lighting, and bits of heating on 10kWh like @HazelPaddy, you're probably looking at 3-5 days depending on how brutal the weather is. My setup's similar capacity and a winter power cut has me counting fridge cycles pretty quickly.

The trick is knowing your actual draw — stick a Victron BMV on it if you haven't already. Stops you doing maths at midnight while increasingly questioning whether the second freezer was truly "essential."

What's your battery chemistry and what are you actually trying to keep running?

Got a motorhome with 20kWh LiFePO4 and learned this the hard way. Your actual runtime depends on what you're actually running—fridge alone is maybe 100-150W continuous, lighting negligible, but heating/hot water will murder your reserves fast.

Real talk: most folk underestimate parasitic draws. Phone charging, router, security systems all add up. I'd budget for 48-72 hours max on proper essentials if you're disciplined about it.

Best move? Turn off anything non-critical immediately. Forget hot showers, minimise fridge door opens, and if you've got gas heating use that instead of electric.

What size bank are you actually running? And have you got solar to top up during the day? That changes everything—even a small 400W portable panel buys you breathing room.

Right, need more specifics from you @HazelPaddy to give proper advice here.

What's your battery capacity in kWh? And crucially — what are you actually powering? A fridge, lighting, heating, comms? That makes a massive difference.

General rule: essentials typically draw 200-500W continuous (fridge cycles, LED lights, maybe a router). So rough maths — 10kWh would manage about 20-40 hours depending on your actual load profile.

Few things to optimise now:

• Turn off non-essentials completely
• Close doors to minimise fridge work
• Use natural light where possible
• Keep your heating/cooling reasonable

How long the outage lasts matters too — if it's forecast to end soon, you're laughing. If it's extended, you'll want to think about rationing water heating and hot meals.

Post your actual setup and we can give you a realistic timeframe.

Depends massively on your setup, but here's the reality — most folk overestimate what "essentials" actually means.

If you're looking at fridge, lighting, and basics, you're probably pulling 300-500W averaged out. With a decent 10kWh bank, that's roughly 20 hours if you're disciplined. My static caravan setup runs about 400W on essentials and I get a solid day out of it comfortably.

Key thing though — what's your actual capacity? If you've got older lead-acid, you can't discharge fully like you can with LiFePO4. And are you rationing heating? That'll kill your runtime fastest.

If you've got solar, even overcast days help stretch things. Worth checking your charge controller's display if the sun comes back out.

What battery chemistry are you running?

Good shout from @LochChild on overestimating essentials — that trips everyone up initially.

One thing nobody's mentioned yet: check your inverter's idle draw. Some cheaper units consume 30-50W doing absolutely nothing. Over 24 hours that's 0.7-1.2kWh gone before you've boiled a kettle.

From my own motorhome setup running Victron kit, I'd prioritise:

• Lighting (LED only — negligible)
• Phone/comms charging — critical for updates
• Fridge — often the sneaky one, measure actual cycling draw not the plate rating

A clamp meter on each circuit right now will tell you exactly where your power's going. Fogstar cells hold voltage well under load so your BMS readout should be fairly accurate.

What inverter are you running @HazelPaddy? That'll help us nail down your realistic runtime figure.

Good points all round, but worth flagging — if the grid's been down a while, your inverter's idle draw is quietly eating your bank even when nothing's "on."

My Victron Multiplus idles at around 20-25W constantly. Sounds small but that's ~0.5-0.6kWh per day just sitting there.

Also, if you've got a fridge — measure its actual draw with a plug meter rather than trusting the label. Mine pulls way less than the rated figure in practice.

What's your battery state of charge right now @HazelPaddy? That's the starting point for any real estimate.