FlexSF wrote:
I have a 13 mini, and on occasion it gets warm and uncomfortable. In one instance it was warm because the flashlight turned on while in my pocket, and so I turned it off, and it returned to a normal temperature. Same can be said for another instance relating to the camera. Finally, if I don't put the phone on airplane mode while I'm in a space that can't receive cellular coverage, or wifi, the phone will try, aggressively, to connect to to the internet, and will get warm. Also, by going into settings>battery, you'll see what application is causing the battery to get warm.
Your phone is not overheating unless it displays a message saying so, and shutting down to cool off.
It’s called the Second Law of Thermodynamics. Anything that creates or uses energy does so with some loss. That lost energy is expressed as heat. So when you charge the phone it generates heat in the power source, heat in the charger circuit in the phone, and heat as the energy goes into the battery. The faster the charging, the more heat is generated. Likewise when you discharge the battery; not all of the energy from the battery gets to the circuits that use it. Some of it becomes heat.
If you use the cellular network for voice or data, converting energy to radio frequency signals is very wasteful; only about 30% of the energy that goes into the network components comes out as radio signals, the other 70% becomes heat. And signal strength matters; a 1 bar signal requires that the phone boost its transmitter power to maintain a connection, and it isn’t linear. 1 bar uses 10 times as much energy as 4 bars. And it will use the most energy if it can’t find a cellular network at all; it ups its transmitter power to maximum hoping to get a response. An iPhone 12 or newer (including SE 3rd edition) with a 5G signal uses about twice as much energy as an LTE signal, and 5G towers are still not as densely distributed as LTE, so the signal is likely to be weaker, compounding the problem.
