In a long power cut, your phone is still useful for as long as the network lasts: calls, messages, official alerts. Keeping it charged is the problem. Nineteen of the 24 national guides we compiled list a charged power bank, and thirteen list a phone charger and car charger. Only Austria and Slovenia list neither.
What size?
Power banks are rated in milliamp-hours (mAh). A 20,000 mAh power bank charges a typical phone four or five times. That is what we suggest for a household of two adults over 72 hours: enough for a charge a day each, with something left for a torch or radio.
A power bank always delivers less than the number on the label, because some energy is lost converting it to your phone's voltage. To estimate for your own phone, find its battery capacity in the specifications, and don't expect to get the full rated figure out.
| Household | Rough guide for 72 hours |
|---|---|
| 1 to 2 people | One 20,000 mAh power bank |
| 3 to 4 people | Two, or one larger one |
| Anyone using a tablet or medical device | Add capacity for that device |
Bigger is heavier and takes longer to recharge. Two medium power banks are more flexible than one huge one: one can stay at home while another goes in the grab bag.
Keep it charged
A power bank only helps if it is full when the power goes. Power banks lose charge slowly in storage, so:
- Top it up when you check your kit, twice a year, and after any use.
- Store it with its cable next to it. A power bank without the right cable is useless.
- Keep it indoors at room temperature, not in a hot car or a cold shed.
- If a warning comes, charge everything: phones, power banks, torches and radio.
Make the battery last
- Turn on low-power mode and dim the screen.
- Close apps you don't need and turn off Bluetooth and location if you don't need them.
- Use a separate torch, not your phone's.
- Get news from a battery or crank radio rather than streaming. All 24 guides list one. See our emergency radio guide.
- Text rather than call: messages use less power and get through busy networks more easily.
The car as a charger
A car with fuel is also a charging station. A USB car charger lets you charge phones and power banks from the car's socket. Four guides (Estonia, Czechia, Slovakia and Greece) also advise keeping the tank at least half full: petrol pumps need power, and the car may be your way out.
Only run the engine outdoors, never in a garage, even with the door open, because exhaust gas contains carbon monoxide.
Solar chargers: a caveat
Small solar panels and solar power banks are slow, and in a dark winter week they are close to useless. They can help in a long summer outage, or for someone who often camps, but they are no substitute for a power bank charged in advance. Many emergency radios include a small solar panel and a USB port; treat that as a bonus, not your main supply.
What about bigger power stations?
Large portable "power stations" can run a lamp, a laptop or a small appliance. None of the guides we compiled lists one, and they are not needed for a 72-hour kit. If someone in your household depends on electrical medical equipment, talk to your doctor or supplier about a backup plan.
Checklist
- A 20,000 mAh power bank, charged, with cable.
- A car charger, if you have a car.
- Spare batteries for torch and radio. See batteries for an emergency kit.
- Important numbers on paper, in case the phone dies anyway.
Our power cut checklist covers the rest, and the checklist sizes it for your household.