My iPhone 15 Pro Max heats up when charging

hukalatorium wrote:

I wish there was a way to adjust charging speed with a setting.

This issue only occurs when using a modern charger with high power. Charging with the power adapter that came with older iPhones and a USB A to C cable does take longer, but the phone does not heat up much at all.

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. In particular, fast charging with a 20 watt power source will cause any smartphone to get very warm, so warm it may have to pause charging to cool down after 30 minutes or so.

This won’t do any harm to the phone, but if you don’t want it to happen use a lower current power source or charge wirelessly.

Phildo8 wrote:

(Apologies for such a long drawn out comment) I’ve been in wireless sales/repairs for 20yrs maybe I can inform on the topic. You’re not alone this happens to my iPhone 15 Pro ALL THE TIME whenever it’s charging & I’m using it to play a game, play music, browse online, etc. without fail after 30-45mins at most I’ll get the pop up saying “Charging will resume when iPhone returns to normal temperature. I do have some “informative” input. It IS an iPhone 15 Pro/Pro Max issue.

Sorry, it is not an “issue”. It is a FEATURE that was added in iOS 16 to all iPhone models that support it. When you fast charge a phone it gets warm. Physics rules, specifically the 2nd law of thermodynamics. The phone pauses charging at 80% to allow the accumulated heat to dissipate. All iPhones always have paused at 80% when fast charging. The only difference is that with iOS 16 Apple added a message that it was pausing; it is not a change in operation, it is only letting you know what it has always done.

The irony is that before this message was added this forum had a steady stream of posts “why does my phone stop charging at 80%?

If the phone gets too hot to operate safely it shuts down. If that hasn’t happened it is within its normal operating range. It is not a problem of any kind, big or small. ALL battery operated devices will get warm in normal use, and (if you like) hot if you are stressing it to its limits. Specifically, if you fast charge it, use it with cellular data with a weak signal (especially 5G), use the camera for extended periods of time, watch videos, or play interactive video games. Or do any of these things while charging it. And it will get even hotter if you have it in a fully enclosing case, because then there is no way for the heat to escape.

I wish there was a way to adjust charging speed with a setting.

This issue only occurs when using a modern charger with high power. Charging with the power adapter that came with older iPhones and a USB A to C cable does take longer, but the phone does not heat up much at all.

So you want me to charge my phone slower than it already is , just so it doesn’t heat up. It’s not a response as to why it’s getting hotter the reason it gets hotter is because it’s messed up and it’s a flaw which apple should have fixed pre-release. My iPhone 13 Pro is also 5g so don’t start on that or anything , it doesn’t merely get heat anywhere near the same amount as my 15pro

Where did I say that? There is no problem with it getting warm. It’s NORMAL to get warm when charging. It isn’t a flaw, it’s basic physics.

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. In particular, fast charging with a 20 watt power source will cause any smartphone to get very warm, so warm it may have to pause charging to cool down after 30 minutes or so.

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.

bigjoed wrote:

by turning off background processing on the 15 in the battery settings before charging the 15 doesn’t get nearly as hot for me SO this is definitely a software issue.

Yes, by turning off background processing that stops the SOFTWARE that runs in the background from running. So it is definitely a software problem, the problem that running software uses energy, and thus produces heat. And when you let software run while charging the entropy of charging and running is additive.

It is perfectly normal on all phones. 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.

(Apologies for such a long drawn out comment) I’ve been in wireless sales/repairs for 20yrs maybe I can inform on the topic. You’re not alone this happens to my iPhone 15 Pro ALL THE TIME whenever it’s charging & I’m using it to play a game, play music, browse online, etc. without fail after 30-45mins at most I’ll get the pop up saying “Charging will resume when iPhone returns to normal temperature. I do have some “informative” input. It IS an iPhone 15 Pro/Pro Max issue. I’ve been in wireless retail since ‘04 after graduating HS. I got a job at a Nextel(hands down BEST carrier & features EVER! Especially the direct connect) My store was a retail & service repair center. So the past 20yrs have taught me a TON about wireless especially being a certified wireless repair tech I’m also certified by Apple to do service & repair. I’ve been with my current store now going on 4yrs. I’m a Retail Store Manager at a VZW store. Granted not corporate Verizon but w/the biggest Verizon franchise in The US(Wireless Zone) so I’m not but 1 step below corporate stores & customer care far as what we can and cannot do in my store & the only sole difference is we absolutely cannot adjust/credit a customer’s account. This is a very well known issue to Apple according to my stores Apple Representative however for whatever reason they’ve been unable to pinpoint the bug bc normally a software update would fix all across the board. However in this case that will not work, clearly if we’re still experiencing it since the base iPhone 15/15+ don’t have the issue so it’s something in 15 Pro/Pro Max boards or software. So who knows honestly when it’ll be fixed. My Apple Rep seems to believe that while it’s a huge inconvenience to users it doesn’t rank high enough on list versus other known issues therefore it’ll probably be a long time if ever.

I think everyone understands what you’re saying about thermal dynamics and such BUT why does only the 15 pro max get that hot? My 16 Pro Max doesn’t get anywhere near as hot.

by turning off background processing on the 15 in the battery settings before charging the 15 doesn’t get nearly as hot for me SO this is definitely a software issue.

No it is not a problem, but if it bothers you don’t fast charge it. Get a 7.5 watt wireless charge pad or use a 5 watt Apple “cube”.

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.

Problem is that all phones don’t warm up like my daughter’s iPhone 15 pro max. Apple has acknowledged that they are working on an update for this issue. Other phones don’t have the issue. So obviously the law of thermodynamics would dictate that this would affect all phones and all manufacturers. This is a 15 pro max problem.

Hi all, I bought the 15pm last May and since the beginning my iPhone gets hot while charging, but I noticed that when I charge it via Laptop and cable USB-C it doesn’t get hot

If it doesn’t turn off to cool down it is not overheating. And the fact that when you charge it with a 7.5 watt Qi charger it will not get as hot as with a 20 watt fast charger that proves it. That’s simple physics.

No, you cannot use that to tell people it’s normal my 15 promax is a replacement after I got a new one and I charge it Without using it at all.

my iPhone 14 Pro and 13 Pro Max never heat up when I charge them. That law is correct but it shouldn’t hit up the phone. The phones can slightly get warm while charging when you don’t use it.