Offline and out of power are different problems

The most awkward time for a phone to run out of battery is rarely while scrolling at home. It is at the station barrier, outside a gig or at a hotel reception, when the device also holds your ticket, payment card or room key. Some phones can keep a few useful functions working after the screen goes black. That does not mean every app or digital pass remains available. Understanding the difference can spare you an unpleasant surprise, especially when you are relying on one device to get home.

Losing a signal and losing power can leave you staring at an unusable app, but the solutions differ. With a charged phone, downloaded maps, music and some tickets can still be opened without mobile data. Once the phone loses power, those saved files may be perfectly intact and completely inaccessible.

That matters when a venue tells you to download a ticket before arriving. Usually, the advice deals with poor reception or a busy network. It does not promise that a phone with a flat battery can display a barcode.

Before a long day out, think about where you will next need the screen. If your return ticket or booking details are on it, finding during a break is more useful than waiting until you reach the gates. Check the connection available and allow time for the handset to restart.

Power reserve buys time for certain tasks

Apple’s Express Mode allows certain compatible cards, keys and passes in Wallet to work without unlocking the phone. On supported iPhones, some of these items can also work in power reserve for up to five hours when the phone needs charging.

This is possible because a phone can retain enough energy for a limited contactless transaction even when it cannot run normally. It is a specific capability, rather than an extra five hours of ordinary phone use. You cannot assume that a shopping payment, hotel key or travel pass will work simply because it appears in Wallet.

Before relying on power reserve, check these details while your phone is still working:

• Your iPhone model supports the feature.
• Your particular card, pass or key is compatible.
• Express Mode is enabled for the card, pass or key you need.

There is another easy detail to miss: Apple says Express Mode power reserve is unavailable when you manually switch off your iPhone. A deliberate shutdown and a phone reaching its charging threshold do not behave identically.

A saved ticket still needs a way to open it

Ticketmaster advises customers to view mobile tickets in its app before reaching the venue, so they are available offline. Adding an eligible ticket to your phone’s wallet is another option. Both are useful preparations, but a barcode ticket still needs a working screen for someone to scan it.

A screenshot is not a universal backup either. Ticketmaster does not accept screenshots for mobile entry, and some tickets use moving barcodes. Follow the instructions for the actual ticket you have bought instead of assuming that a saved image will be enough.

If you spot a low battery while you still have time, a lets you keep the phone beside you while it charges. Open the ticket afterwards and check that it is ready to show.

It also helps to have the order number somewhere other than your phone. Ticketmaster directs customers with a flat or broken handset to the venue’s box office with identification and their order details. Check the arrangements for your event before travelling.

A phone can be findable without being usable

A phone that has stopped responding may still help its owner locate it. This uses a separate feature from the one that lets an eligible travel card work at a reader.

Apple says supported iPhones with Find My network enabled can be located for up to 24 hours after being switched off, or up to five hours in power reserve. Those are different situations; the longer figure does not mean a flat iPhone will remain findable for another full day.

Google offers a similar capability through Find Hub on supported phones, including compatible Pixel models. These can remain findable for several hours after shutting down or running out of battery, with network finding enabled and Bluetooth and Location on at shutdown.

Offline finding uses nearby participating devices to detect a Bluetooth signal and report a location. It can help recover a phone left behind, but it cannot restore the screen or make a ticket available to scan.

Neither service guarantees an immediate, current location. Check the time shown alongside a result, because a last known position may be all that is available. Make sure you can access your account from another device, including any necessary recovery method, before you need it.

Make a backup plan for getting home

Plan around the things you must do after leaving, rather than trying to protect every app. A payment card and a written booking reference can be useful, although each service has its own rules.

On London transport, for example, TfL requires the same card or device for touching in and out. The physical bank card linked to your phone is not interchangeable with it halfway through a journey. Ask staff for help if the phone fails.

are available, a break can be a good opportunity to charge while you do something else. Use a code you can easily remember, and retrieve your phone before you need a ticket or key.

If you are going out with other people, make two arrangements before leaving:

• Agree exactly where to meet if someone loses contact.
• Write an essential phone number on paper so you can use a borrowed handset.

Before setting off again, check the functions you will actually use. Power reserve is useful when supported, but a working phone and a practical backup give you more options.