No mains, no wifi, and a mast that may not last the night
A power cut has a predictable sequence. The lights and the router go first, so home wifi is gone within a second. The mobile network usually keeps working, because masts have batteries, but those batteries are measured in hours rather than days, and in a wide area outage the network gets congested long before it fails. Somewhere in that window your phone becomes a torch, a radio and a map, and only if the right things are already on it.
This is preparation, not emergency advice. In a genuine emergency, the number for the emergency services works on any phone with any signal, including one with no SIM in it.
What stops working, and when
| Time since the cut | What still works | What to do about it |
|---|---|---|
| Immediately | The phone, on its own battery | Drop the screen brightness and turn off what you do not need |
| Immediately | Mobile data, usually | Download anything you still need now, not later |
| First hours | Calls and texts, congested | A text gets through when a call will not |
| Several hours | Masts running on their own batteries | Assume the signal may go, and stop relying on it |
| Overnight | Whatever is stored on the phone | Offline maps, offline reading, a torch |
| Next day | Your remaining battery, and nothing else | This is why a power bank matters more than any app |
What to have on the phone already
A torch that opens instantly, has a widget and does not need the network. The screen at full brightness is a worse torch and costs several times the battery.
Offline maps with real detail, including footpaths and contour lines. Download the whole region rather than the city, because the reason you are navigating is usually to leave.
The friendlier offline map with fast search. If one offline map app gets installed, most people should make it this one.
Download the offline area anyway. Routing and search keep working inside it, which covers the ordinary case without a second app.
Reads offline copies of Wikipedia and other reference collections. A few gigabytes buys an encyclopaedia that works with no network at all.
The lighter version of the same idea: save the articles for where you live and where you might go, and they stay readable offline.
An offline field manual, open source and entirely local. Worth having for water, shelter and first aid basics even if you never expect to use it.
First aid guidance from the international Red Cross and Red Crescent, stored on the phone. It is a reference, not a substitute for calling for help.
Internet radio, so it needs data, but local radio is where outage information is actually broadcast in most countries.
Uses the phone's FM tuner where the hardware and the region allow it, which means no data at all. Test whether it works on your phone now, because many handsets and carriers never enabled the chip.
Listens to public emergency service feeds where they are published. Needs a connection, and coverage varies enormously by country.
Push to talk over any connection, and far more tolerant of a weak one than a voice call. Set up the channel with family before you need it.
Bluetooth mesh messaging between nearby phones with no network. The range is short and the reliability is mixed, so treat it as a curiosity rather than a plan.
Weather and official warnings from sources you choose, with no advertising and modest data use.
Shows what is actually draining the battery and how much is left in real terms. The most useful app here on day two.
Compass, altitude, sun and moon times and a backtrack trail from the phone's own sensors. No network, no account, no data.
Shared location for a family that has split up during an outage. Worth knowing that it shares that location continuously, which is a privacy decision to make deliberately.
Not for the outage itself: for the scans of your insurance documents and identity papers, marked available offline before anything happens.
Making one battery last two days
- Turn the screen down and the timeout short The screen is the largest drain by a wide margin, ahead of everything else combined.
- Use aeroplane mode between checks A phone hunting for a weak signal flattens itself faster than a phone in use. Turn the radio on for ten minutes an hour.
- Send texts rather than making calls They use less power, and they get through a congested network that will not carry a call.
- Turn off background sync and location Nothing needs to update while the power is out, and location is the second largest drain after the screen.
- Charge the power bank before the storm, not during it This is the one preparation that matters more than any app, and the one most often skipped.
- Torch, compass and sensors
- Downloaded maps and routing
- Offline encyclopaedia and manuals
- Anything already saved on the phone
- Internet radio and scanner feeds
- Live outage maps from the utility
- Messaging and push to talk
- Cloud documents you did not mark offline
Download the maps and the reference material now, keep a power bank charged, and remember that the phone lasts twice as long in aeroplane mode.
Frequently asked questions
Will my phone still make calls if the power is out?
Usually, for a while. Mobile masts have battery backup measured in hours, and in a wide area outage congestion bites before the batteries do. Texts get through when calls do not.
Is FM radio on a phone a real thing?
On some phones, yes: a tuner chip that needs wired headphones as an aerial and no data at all. Whether it is enabled depends on the handset and the carrier, so test it before you rely on it.
What is the single most useful thing to have?
A charged power bank. After that, an offline map of where you live and a torch app with a widget. Everything else on this list is a refinement of those three.
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