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My new iphone is becoming too hot. Is it normal. Should I return it?

It is becoming hot while charging

Posted on Jul 16, 2023 10:23 AM

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Question marked as Top-ranking reply

Posted on Jul 16, 2023 12:07 PM

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. You didn’t mention your phone model, but 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.

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Question marked as Top-ranking reply

Jul 16, 2023 12:07 PM in response to ShivaThatikonda

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. You didn’t mention your phone model, but 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.

Sep 27, 2023 3:40 PM in response to ShivaThatikonda

I've had my 14 Pro Max for only a year, since updating to IOS17 and just today the newest update when I charge Wirelessy even with a case I have noticed my phone becoming extremely hot.


This is using the Apple MagSafe charger btw. Not until I read about the rumblings on the new iPhone15 did I start to look into it and never knew about this forum as almost everything on Google Search makes it seem as it’s normal.


Now I’m convinced this is not normal and wonder how this affected my actual battery, as I just checked my battery maximum capacity and am baffled after just having it brand new for barely days over a year it is at 90% while I’ve had my 12 ProMax for I believe over 2yrs and that has way more apps, files, photos etc on it and is at 90%.


Although my Apple Support is expired I didn’t bother reaching out because I need to pay them to be heard, but am glad I was able to discover this discussion board just in case someone is going thru a similar experience while charging on the MagSafe with a case after updating to the 17.0.x

My new iphone is becoming too hot. Is it normal. Should I return it?

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