Series 15 iPhones in a brick-and-mortar store: not everyone is happy
Photo: IMAGO/Mahmoud Ajjour / IMAGO/ZUMA Wire
It started seemingly harmlessly: When charging with fast charging, his iPhone 15 Pro becomes "too hot to touch," wrote Ian Zelbo of the tech blog 9to5Mac on Monday of this week on X, which used to be called Twitter. It soon became apparent that Zelbo was not alone: several other users reported similar experiences. YouTubers and bloggers jumped on the topic, exposing the new Apple smartphones to all kinds of stressful situations. Some used thermal imaging cameras to measure the temperatures on the outside of the devices, including SPIEGEL.
The Korean YouTuber BullsLab, for example, shows measured values of up to 46.7 degrees Celsius on the backs of iPhone 15 and iPhone 15 Pro in a video. Another user posted a video on Twitter in which he measures 42 degrees Celsius. He leaves it unclear what the device was doing at that time.
In many cases, a possible explanation for the unusually high temperature can be that apps, music, videos, photos and other data are still being downloaded from the cloud in the background after the initial setup. This process puts so much strain on a number of components that the device can heat up – even though it doesn't seem to do anything.
It's not just iPhones that are getting hot
However, some of the reports of Apple phones being too hot explicitly rule out this phenomenon. For example, the blog "Android Authority", whose iPhone 15 heated up during less demanding tasks such as chats and Instagram.
YouTuber Vaibhav Jain has compared the outside temperature of an iPhone 15 Pro Max with that of a Xiaomi 13 Pro. His result: the iPhone gets quite warm at 43 degrees Celsius, but the Xiaomi heats up even more at almost 48 degrees Celsius.
SPIEGEL has tried to reproduce the problem with several test devices. We hooked up an iPhone 15 Pro with a fully discharged battery to a powerful power adapter, watched videos on Instagram, TikTok and YouTube on an iPhone 15 Plus in quick succession, and played a pre-release version of the graphically demanding game "Resident Evil Village" on an iPhone 15 Pro Max. And we always measured the temperature on the back of the devices with a thermal imaging camera from Seek Thermal. The meter did not show more than 31 degrees Celsius in any case. Too little to get upset.
Is it the SIM slot?
However, this does not mean that the phenomenon does not exist. The only thing that is unclear is what the cause is, why some people experience heat build-up, while others do not. Apple has not yet commented on the reports. Apple technicians refer users who complain about iPhones that are too hot to a support page on the subject that has been around for years.
Meanwhile, mainstream media are also struggling to find an explanation. The Wall Street Journal, for example, writes that the heat problems could be due to design flaws. For example, the SIM card slot is cited as a possible weak point in heat dissipation. In the USA, iPhones only work with electronic SIM cards, so-called eSIMs. However, until then, iPhones had always had SIM slots without experiencing any heat issues. Nor would that explain why heat reports come from all over the world and not just from countries where iPhones are sold with or without a SIM slot.
Troubleshooting Titan and Instagram
Renowned analyst Ming Chi-Kuo also has a possible explanation. In his view, "compromises in the thermal system" could be the cause of the heat problems. In order to reduce the weight of the devices, Apple has reduced the area over which heat can escape from the case. In addition, the titanium that makes up the outer frame would impede heat dissipation. The new A17 Pro chip, which is only in the two Pro iPhones, is ruled out as a source of error.
According to the analyst, Apple could at least partially contain the problem via software update. However, real relief would only be possible if the company were to cut the performance of the chip. In doing so, however, it would virtually deprive its top models of their right to exist. The increased performance of the A17 Pro and the resulting capabilities, such as realistic ray-traced graphics in games, are among the arguments used to lure buyers to the more expensive models, along with the better cameras.
A completely different possible explanation is provided by the tech blogger Faruk. In a YouTube video, he shows how the temperature of his iPhone 15 Pro Max rises significantly, while at the same time decreasing the battery capacity by one percent per minute after launching the Instagram app. Even when idle, the app seems to put a lot of strain on the system. His tip: activate the power-saving mode in the settings under Battery and switch off the background refresh in the Instagram settings. It remains unclear whether the phenomenon he shows can explain all reported cases of heating.
Here's what you can do if your iPhone gets warm
Whether the reported heat issues are actually a design flaw, isolated cases, or something else entirely, there are a few tips to heed if you feel like an iPhone is heating up too much.
Remove the protective case if you have put one on your Apple phone. Such shells can make it difficult to transport heat from the device to the environment.
Charge your iPhone 15 with a weak power adapter. Chargers with only five or ten watts of power take a long time to pump up the battery, but they also generate less heat.
Quit apps running in the background and restart the iPhone. To do this, press the volume up and down buttons in quick succession, then press and hold the power button until the phone restarts and the Apple logo appears.