Normal warm, or a problem?
| What's happening | Usually means |
|---|---|
| Warm while fast charging, then cools once full | Normal |
| Warm during games, video calls, GPS navigation or 4K video | Normal, especially with the screen bright |
| Hot in a parked car or on a sunny dashboard | The heat outside, not a fault, but it wears the battery |
| Hot while sitting idle, screen off | An app running flat out in the background, or a fault |
| Hot every time it charges, with any charger | A worn battery or a charging fault |
| Hot and the battery drains fast | A worn battery, or an app stuck running |
| Hot and the screen lifts or the back bulges | A swollen battery: stop charging it |
What the phone does when it's too hot
Phones protect themselves. As they heat up they dim the screen, slow down, stop the camera flash, and pause charging. On an iPhone you may see Charging On Hold, or a full-screen Temperature message saying it needs to cool down before you can use it. Galaxy and Pixel phones show similar warnings. These are safety features, not faults: let it cool and it carries on.
Apple says iPhones work best between 0 °C and 35 °C. An Ipswich summer day goes past that easily, and a car parked in the sun gets far hotter.
How to cool it down safely
- Stop charging and close the app that's working it hard (a game, the camera, navigation).
- Take it out of the case, especially a thick or leather one.
- Move it into the shade or an air-conditioned room.
- Let it cool on its own. Don't put it in the fridge or freezer: sudden cold can cause condensation inside, which is worse than the heat.
- Turn it off if it's still hot after ten minutes.
Common causes, and what to do
Charging in the heat. Fast charging makes heat; so does the sun. Charge somewhere cool, out of a thick case, and not on the dashboard. Wireless chargers run warmer than cables.
A cheap or damaged charger or cable. A charger that doesn't regulate power properly can overheat the phone and itself. Use the phone's own charger or a reputable brand, and replace frayed cables (here's how to pick a safe charger).
An app stuck running. Look at the battery settings: Settings → Battery on iPhone and Pixel, Settings → Battery → Battery usage on many Galaxy phones. An app using far more than usual is the likely culprit. Force-close it, update it, or remove and reinstall it. A restart often clears it.
Weak signal. A phone working hard to hold onto a weak mobile signal or searching for Wi-Fi heats up and drains fast. If it only happens in one place, that's probably the reason.
A worn battery. As batteries age, their internal resistance rises and they make more heat while charging and under load. If your phone is a few years old, gets hot while charging and doesn't last the day, the battery is the most likely cause. A battery health reading helps: Settings → Battery → Battery Health on iPhone, or the Samsung Members app's battery check on Galaxy phones.
Damage inside. A phone that's been dropped or got wet can develop a short circuit that makes heat even when idle. That needs a repair.
When to stop using it
Stop using and charging the phone straight away if:
- the screen is lifting, the back is bulging, or the phone no longer sits flat;
- it's too hot to hold, or hot while switched off;
- there's a chemical smell, hissing or smoke.
If there's smoke or fire, move away from it and call Triple Zero (000). Otherwise, unplug it, keep it on a non-flammable surface away from anything that can burn, and get the battery seen to.
Sources
- Apple Support: If your iPhone or iPad gets too hot or too cold
- Queensland Fire Department: Lithium-ion battery safety
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