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Turn on your phone’s built-in battery-saving mode immediately, dim and limit the display, stop power-hungry apps and radios, and reserve connectivity for essential messages and calls. Use Airplane Mode only when you can safely give up cellular service. A power bank or car charger can recharge the phone, but no setting provides a guaranteed number of extra hours.
What to do first when the power goes out
Battery conservation works best when you start before the charge is critically low. A phone that is already searching for a weak signal, keeping its display on, or running navigation can lose useful capacity quickly. Take these actions in order:
- Check the battery percentage and turn on the built-in saver. Use Low Power Mode on an iPhone or Battery Saver on a Pixel. If a Pixel is nearly empty, consider Extreme Battery Saver.
- Dim the display. Keep it bright enough to read safely, then lock the phone instead of leaving the screen awake.
- Stop demanding activity. Exit video, games, navigation, streaming, hotspot/tethering, camera, and other apps you do not need for the emergency.
- Decide whether cellular service is essential. If you must receive calls or messages, leave cellular connectivity available. If there is no service and you do not need the network for a period, Airplane Mode may prevent repeated network searching.
- Tell the people who need to know. Send a short, essential message rather than holding a long conversation, then put the phone away until you need it again.
The U.S. Department of Energy (DOE) advises keeping calls brief and limiting communication to vital information during an outage. Follow local emergency-management and utility instructions if they differ from general conservation advice.
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Turn on the correct battery-saving mode
iPhone: Low Power Mode
Apple’s current instructions distinguish between newer and older iPhones:
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- iPhone 15 and later: open Settings > Battery > Power Mode > Low Power Mode.
- iPhone 14 and earlier: open Settings > Battery > Low Power Mode.
Low Power Mode reduces background activity and changes several behaviors that consume charge, including display brightness, email fetch, automatic downloads, and Background App Refresh. It is a useful first action because it limits work you might not see happening. Apple says Low Power Mode turns off automatically after the iPhone reaches 80 percent charge, so enable it again if the outage continues and the phone has charged past that point.
Menu names can change with iOS updates. If you do not see the exact path, open Settings and use its search field for “Low Power Mode.”
Pixel: Battery Saver or Extreme Battery Saver
Google’s Pixel guidance recommends Battery Saver when the battery is running low and Extreme Battery Saver when the battery is about to die. The exact controls can vary by Pixel model and software version, so open Settings and search for “Battery Saver” if the path on your phone differs.
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Why enabling the saver early matters
Battery-saving modes cannot recover charge already consumed. Enabling one at 20 percent is still worthwhile, but enabling it at 80 or 60 percent prevents background work from using that capacity while you are deciding what to do. Neither Apple nor Google provides a universal number of extra hours because the result changes with the phone model, battery condition, signal, temperature, and what you do with the device.
Reduce screen and app drain
Keep the display off except when needed
The screen is one of the most visible sources of consumption. Lower brightness, read what you need, and lock the phone immediately. Avoid repeatedly waking it to check the percentage or notifications. If you need to monitor messages, check at planned intervals rather than leaving a chat or status screen open.
Low Power Mode can reduce brightness on an iPhone, but still dim the display manually if it remains brighter than necessary. On any phone, a dark room generally lets you use a lower brightness than daylight; do not reduce it so far that you cannot safely read an emergency instruction.
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Stop high-energy activities
Google specifically cautions against activities that keep the processor, display, camera, location services, or network active. During an outage, avoid:
- Video playback and video streaming
- Graphics-heavy games
- Long navigation sessions or map use
- Hotspot or tethering for another device
- Prolonged GPS or location tracking
- Extended social-media or web browsing sessions
- Frequent camera use, especially video recording
- Unnecessary app use that keeps the screen awake
Download or write down directions, contact details, and other information before the battery becomes low if you have a safe opportunity. Do not keep a navigation app running simply to display a route you already know; open it briefly to confirm a turn, then lock the phone.
Manage Bluetooth and Location selectively
Turn off Bluetooth when you are not using wireless headphones, a vehicle connection, a medical accessory, or another device that you genuinely need. Disable Location services only when location-dependent apps and features are unnecessary. Google warns that turning Location off can stop or degrade those functions, so do not disable it if you need location sharing, navigation for evacuation, or an emergency feature that depends on your position.
Likewise, do not close every app reflexively. The important decision is whether an app is actively using the screen, network, camera, GPS, or background updates. Keep the communication and safety tools you may need; stop the entertainment and synchronization that you do not.
Use Airplane Mode only after weighing the communication trade-off
Airplane Mode can save power when the phone is repeatedly searching for a network you cannot use. Google recommends enabling it if the mobile network is not needed, and Apple documents that Airplane Mode prevents calls. With it on, ordinary cellular calls and text messages will not arrive or leave through the mobile network.
Choose Airplane Mode when all of these are true
- You are in a no-service area or cellular service is unavailable for a known period.
- You do not need to receive a call or text during that period.
- You have another way to receive urgent information, or you have arranged a specific check-in time.
In this situation, Airplane Mode can stop the phone from spending energy searching for a tower. It may also disable or disconnect other radios depending on the device and the settings you leave enabled.
Leave cellular service available when it matters
Do not use Airplane Mode merely to chase a small battery saving if you are waiting for an emergency call, an evacuation instruction, a welfare check, or a message from a household member. Instead, keep cellular service on, silence nonessential notifications, and check the phone at intervals. You can enable Wi-Fi or Bluetooth separately if your phone permits it and those connections are genuinely useful, but verify that the needed service works before relying on it.
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Return to normal connectivity deliberately
When you need to call, send a message, share your location, or receive an alert, turn Airplane Mode off and wait for the phone to reconnect before concluding that service is unavailable. After the communication is complete, decide whether to leave cellular service on for incoming contact or return to Airplane Mode for another no-connectivity period.
Communicate briefly and preserve emergency access
During a prolonged outage, communication discipline can save more charge than repeatedly changing minor settings. Prepare one concise message containing your status, location if appropriate, and the next time you expect to check in. Send it once to the people who need it rather than conducting a long conversation.
- Use calls for urgent, time-sensitive information.
- Keep necessary calls short and end them when the essential facts are exchanged.
- Do not stream or remain in a video call when a short text or voice call is sufficient.
- Keep enough charge for emergency services and the people responsible for your safety.
- Check official local alerts at sensible intervals instead of refreshing continuously.
Never disable the only communication method available to you for a marginal battery saving. Battery conservation supports safety; it does not replace the need to call for help when there is an immediate threat.
Charging options when the grid is down
Use a power bank as a backup charger
A USB phone power bank, also called a portable phone charger, can recharge the phone when wall power is unavailable. It is an external energy source, not a battery-saving setting, and it does not extend the existing charge unless you connect and use it. The researched guidance does not establish a particular capacity, model, charging speed, or performance figure, so check that any power bank has a connector and cable compatible with your phone.
To conserve both sources of energy, connect the power bank when the phone is low enough to need it, keep the phone’s display off while charging, and disconnect when the available backup power is reserved for a more important later use. If the power bank itself is nearly empty, changing phone settings will not replenish it.
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Use a compatible car charger
The DOE specifically recommends a car charger as one way to keep a mobile device available during an outage. Confirm that the charger fits the vehicle’s power socket and your phone’s cable. A car charger transfers energy; it does not make the phone consume less, so continue using Low Power Mode, a dim display, and short communications while charging.
Follow ventilation and vehicle-safety rules
If the car must be running to charge the phone, place it in a well-ventilated location. Never run it in a garage or another enclosed space because exhaust can accumulate. The DOE advises removing the car from the garage before charging, once the immediate danger has passed. Do not leave people, pets, or the vehicle unattended in a hazardous location, and follow state and local emergency-management directions for the incident.
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Keep spare batteries and cables ready
DOE guidance also recommends spare phone batteries. For phones with sealed batteries, the practical equivalent is a charged power bank or another approved external source. Store the phone cable, car adapter, and backup charger together so you are not searching for them after the outage begins. Periodically check that the backup source still holds a charge and that the cable is undamaged.
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| Battery situation | Priority actions | Connectivity decision |
|---|---|---|
| More than half full | Enable the saver early, dim the display, stop demanding apps, and prepare a short check-in message. | Keep cellular service on if you need incoming contact; use Airplane Mode only during a deliberate no-service period. |
| Low and falling | Use the most restrictive built-in saver appropriate to your phone, lock the screen, and avoid video, games, navigation, hotspot use, streaming, GPS, and camera sessions. | Limit calls to vital information. Consider Airplane Mode only when you can safely miss cellular calls and messages. |
| Nearly depleted | On a Pixel, consider Extreme Battery Saver. Keep only emergency and essential communication functions available, and seek a power bank or car charger. | Preserve enough charge to contact help. Do not cut the only available emergency connection simply to extend standby time. |
| Charging from a backup source | Keep the display off while charging, use a compatible cable, and disconnect when you have enough reserve for the next essential task. | Continue the saver mode; charging does not remove the need to limit network and screen use. |
Why no setting promises a fixed number of extra hours
Two phones showing the same percentage can have very different usable runtimes. Relevant factors include:
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- Battery age and condition: a worn battery stores less energy than it did when new.
- Signal strength: a phone can use more power while searching for or holding a weak connection.
- Screen and radio use: brightness, video, GPS, Bluetooth, Wi-Fi, and cellular activity change consumption.
- Temperature: extreme conditions can affect battery behavior and charging.
- Software and settings: operating-system versions and enabled background features vary.
Apple and Google explain which behaviors their modes reduce, but the official guidance does not give a universal outage-specific percentage or extra-hour figure. Treat any fixed promise as applying only to a particular phone and test condition, not as a guarantee for yours.
Common mistakes and how to correct them
Turning on Airplane Mode without realizing calls are blocked
Symptom: family members cannot reach you. Correction: turn Airplane Mode off when incoming cellular contact is important, then use brightness and app controls to reduce drain instead.
Leaving a streaming, game, or map session open
Symptom: the percentage drops quickly even though the phone is not being held. Correction: stop the app, lock the display, and use a saved note or downloaded information when possible.
Disabling Location before checking its consequences
Symptom: navigation, location sharing, or a safety feature stops working. Correction: restore Location services for the task, use it briefly, and disable it only when you no longer need that function.
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Waiting until the phone is almost dead to find a charger
Symptom: the backup charger or cable is missing when communication becomes urgent. Correction: keep charged spare power and compatible cables in the same accessible place before an outage.
Charging a running car in an enclosed space
Symptom: the vehicle is in a garage or poorly ventilated area. Correction: do not run the engine there. Move the vehicle to a well-ventilated place only when it is safe, following local emergency instructions.
Quick Recap
Power-outage phone checklist
- Battery-saving mode is on.
- Brightness is as low as practical, and the screen is locked between uses.
- Video, games, streaming, navigation, hotspot, prolonged GPS, and unnecessary camera use are stopped.
- Bluetooth and Location are off only when their functions are not needed.
- Airplane Mode is used only during a period when cellular calls and messages are not required.
- Calls and messages are brief and limited to essential information.
- A compatible cable, USB power bank, or car charger is available.
- Any running vehicle used for charging is outdoors or otherwise well ventilated.
- Local emergency-management, utility, and public-safety instructions take priority over generic battery advice.
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