Anyone else keep a "OH NO" battery box ready for proper grid outages?

After that 14-hour outage in January I knocked together a grab-and-go setup from the boat — 100Ah Fogstar lithium, a Victron 375VA inverter, and a 30W Renogy panel bungee-corded to the fence. Kept the fridge and a few phone chargers ticking over without breaking a sweat.

Cost me about £340 all-in using bits I already had kicking around, which felt smug-worthy when the neighbours were panic-buying candles from the Co-op at midnight.

Curious what others have cobbled together — anyone running something beefier, or is it all just a dusty generator in the shed that hasn't started since 2019?

BigAl31 | 847 posts | Yorkshire

@DazHenderson77 Brilliant idea mate, that January outage was a proper wake-up call for a lot of people! I've had a similar setup sitting in the garage for a couple of years now — 120Ah lithium, small Victron multiplus, and a folding 100W panel I can lean against the garden wall in about two minutes flat.

One thing I'd strongly recommend adding is a decent 12V water pump if you're on a private borehole or have pressure issues when the grid drops. Caught me out badly the first time round.

Also worth keeping a pre-charged state above 80% at all times — I've got a cheap plug-in trickle charger keeping mine topped up constantly so it's never sitting half flat when you actually need it. Cheap insurance really.

24V_Geek | 1,203 posts | Cambridgeshire

@DazHenderson77 Nice one Daz, the Fogstar cells are solid for exactly this kind of duty. I've gone slightly different route — dedicated 200Ah box that lives in the garage permanently wired to a small rooftop panel via a Victron SmartSolar, so it's always topped up without me thinking about it. Lesson learned after I grabbed my "emergency" battery during the 2022 storms and found it sat at 40% because I'd been raiding it for camping trips 😅

The always-trickle-charging approach is the real game changer for peace of mind. @BigAl31 worth considering if you're building something permanent — you never want to be hunting for the charger when the lights go out!

@DazHenderson77 Living on a narrowboat means every day is an "OH NO" box situation — mine's just called the boat.

RussGreen | 312 posts | Array

My van conversion basically is the OH NO box — 200Ah Fogstar, Victron SmartSolar, and a folding panel that lives under the bed. During that January outage I just backed the van onto the drive and ran an extension lead inside.

Only thing I'd add to @DazHenderson77's setup — worth having a small DC-DC charger so you can top the battery from the car if the solar's struggling in winter. A Victron Orion-Tr Smart is ideal for this. January sun in the UK is basically decorative.

Also thinking about EV charging implications — if grid outages become more frequent, a proper battery buffer setup starts making a lot of sense for protecting your wallbox too.

MoorLee | 847 posts | Array

Mine's a 200Ah Fogstar on a sack trolley with a Victron Multiplus velcroed to it — I call it The Brick. Wife calls it "that thing blocking the hallway for three years waiting for a power cut."

January finally justified its existence.

My van conversion is the OH NO box, my garden office is the OH NO box, and at this point I'm starting to think I just have a personality disorder with a Victron colour scheme.