Phone overheating during use: apps, charger, battery and when to stop using it

Unplug the charger and switch the device off. Never puncture, bend or heat a swollen battery.

Put a phone that feels hot somewhere shaded and let it cool down before you use or charge it again.

A phone that feels warm is not necessarily faulty. Apple, Samsung and Google name the same activities as causes of warmth: setting up a new phone, restoring a backup, installing a software update, heavy games, long video recordings and streaming high-quality video. Google adds using the phone as a WiFi hotspot and uploading or downloading a lot of data.

According to Apple, these conditions are normal and the phone cools down once the process is finished. As long as no temperature warning appears on the screen, you can keep using the iPhone. Samsung says much the same for Galaxy phones: the phone can feel warm depending on use and surroundings, and system and battery protection features kick in automatically when the temperature rises temporarily.

Heat with no obvious cause is what to watch for. Examples include a phone that gets hot while the screen is off and it is not charging, heat that comes with fast battery drain, or a phone that keeps shutting itself down.

This table sums up the triggers named on the Samsung, Apple and Google support pages, with the first thing to try for each.

Work from the top down, then use the phone as usual for a day to see whether the heat goes down.

1. Close heavy apps first, such as games, the camera, video calls and navigation. Google suggests starting them again once the phone has cooled down.
2. Lower the screen brightness, then turn off WiFi, Bluetooth and location when you are not using them. Samsung points to the Quick panel for all three.
3. On a Samsung Galaxy, open Settings, select Device care, then tap Optimise now. On an Indonesian-language phone the menu is Perawatan perangkat, or Perawatan perangkat dan baterai on some versions.
4. Turn on Power saving through Settings, Device care, Battery. Then open Background usage limits and turn on Put unused apps to sleep.
5. For heavy use, Samsung offers a Performance profile with a Light option, which lowers the processing speed to reduce heat.
6. On a Pixel 6 or later, check the temperature under Settings, Battery, Battery diagnostics, then Phone is very warm.
7. Keep your apps updated, and check the battery status of a Galaxy with the Phone Diagnostics tool in the Samsung Members app.

According to Samsung, Power saving mode lowers the brightness to 10% and limits the CPU speed to 70%, among other things. Menu names and screen layouts can differ between models and software versions, as Samsung itself notes.

A phone and its charger do get warm while charging. Samsung writes that the temperature can be higher with a super fast charger or a wireless charger. Excessive heat usually comes from a charger or cable that is damaged, non-genuine or incompatible. A connector contaminated with liquid, dust or metal particles can also cause it, and so can running heavy apps while fast charging.

If the phone feels hot while charging, unplug the charger and close all apps. Wait until the phone has cooled down, then charge it again. If it still gets hot, try another official charger and cable. When charging wirelessly, make sure there is no metal, magnet or card between the phone and the charger.

The phone also protects itself. Apple says an iPhone slows or stops charging, wireless charging included, when its internal temperature gets too high, and Google says a Pixel reduces its charging speed. A Charging On Hold message on the iPhone Lock Screen means the device is temporarily too hot or too cold to charge.

Apple designs the iPhone for use where the ambient temperature is between 0º and 35º C (32º to 95º F). Apple also asks you not to leave the device in a car, because temperatures in a parked car can go beyond that range. Using it in very hot conditions, Apple says, can permanently shorten battery life.

In Indonesia, phones often sit on the dashboard for navigation or in a phone mount on a motorbike during a midday ride. That habit combines two triggers named by Apple and Google: direct sunlight and long GPS navigation. If you need the phone for navigation, lower the screen brightness and unplug the charger once the phone starts to get hot.

Samsung also names enclosed spaces as a cause of heat: bedding, bags, clothing pockets and places near a heat source. Google asks you not to keep the phone in enclosed or poorly ventilated places. A phone charging under a pillow or in a bag sits in exactly that kind of place.

When the internal temperature goes past the normal range, the phone limits what it does. Apple lists a display that dims or goes black, a weaker cellular signal, a camera flash that is turned off for a while, and some apps that slow down. Google says a Pixel can reduce CPU performance, turn off the camera or its flash, partly turn off mobile data or WiFi, and enter low power mode. Samsung shows a warning message and pauses certain features.

If the temperature warning screen appears on an iPhone, Apple asks for three things: turn the device off, move it somewhere cooler and out of direct sunlight, then let it cool down. A Pixel whose temperature keeps rising can turn itself off; let it cool down before you switch it on again. Apple also writes that very cold temperatures can make a phone turn off or stop charging, so room temperature is all you need to cool the phone down; do not chill it.

Stop using the phone, unplug the charger and take it to the authorized service center for your phone's brand if:

• the back or the screen looks raised, a gap is opening along the edge, or the phone no longer lies flat on a table;
• you smell burning or a chemical odor from the phone;
• the phone stays hot while the screen is off and it is not charging;
• the phone keeps turning off from heat even after it has cooled down, which Google says calls for Pixel support;
• liquid got into the charging connector at some point and the phone now gets hot while charging.

Modern phone batteries are built into the body. Opening the battery pack, taking the battery apart or replacing the battery cells is a job for a service center, not something to do at home. Apple writes that the iPhone battery should only be serviced or recycled by Apple or an Apple Authorized Service Provider. Before you hand the phone in, back up your data if it still turns on.