Is your iPhone getting very warm—or even hot—for no apparent reason, and is the battery draining very quickly? If so, there are exactly two causes for this, and there are also only two solutions to fix the overheating problem. But first, for a better understanding, here’s a brief explanation of why the iPhone (this also applies to Android and Windows smartphones) gets hot in the first place. It’s because of the battery, and when power is drawn from it quickly—meaning a lot of energy is being consumed—it gets very warm and heats up all the iPhone’s components. However, this only happens when something is running on the iPhone and consuming an extremely large amount of power. The result is that you end up with a hot iPhone in your hands. This is a completely normal process, not a defect, but with a little skill and technical know-how, you can easily solve the problem.
If your iPhone gets hot, 99% of the time it’s due to very poor signal reception. You’ve probably set your mobile data connection to LTE or 3G, and if the signal is very weak, the iPhone’s antenna tries to compensate by increasing its transmission power. Sometimes the antenna constantly switches back and forth between LTE, 3G, and 2G, which causes enormous power consumption. This also happens when the iPhone isn’t being used at all; the antenna still tries to establish the best possible connection. This can sometimes cause the smartphone to get hot in your pocket.
Example: In downtown Reutlingen, the e-plus network at the central bus station (ZOB) is so poor that the iPhone’s antenna is completely overwhelmed, constantly switching between 3G and 2G, causing the iPhone to get extremely hot and the battery to drain within a few hours. It even gets to the point where, due to the constant switching of transmission speeds (LTE, 3G, 2G), reception drops out completely, making it impossible to answer or make calls, and also preventing the sending and receiving of text messages.
Solution: If this problem occurs and your iPhone gets too hot even on cold days, you can manually lower the data transfer speed to 2G in the mobile data settings. This reduces the load on the antenna, drastically cuts down on power consumption, cools the battery down very quickly, and ensures excellent mobile data reception for WhatsApp, Facebook Messenger, and other apps. This keeps the iPhone at a normal operating temperature and ensures the battery lasts longer again. If there’s an issue with the cellular network or reception is generally poor, you can always use this trick. It all depends on the antenna, and if it has to transmit like crazy, the iPhone is bound to get hot.
When the temperature outside approaches 30 degrees, all electronic devices have to work a little harder, and it’s perfectly normal for your smartphone to get a bit warmer. But that’s no reason for it to get too warm or even hot. The problem here is the bright sun, combined with a reflective display and the screen’s automatic brightness control. You often use your iPhone in the sun and don’t even notice that the automatic brightness control is cranking the display up to 100% and the device is running at full speed. It’s the same as with the antenna: anything that draws a lot of power — and does so quickly—heats up the battery and, consequently, the entire smartphone. Nothing is broken here, nor do you need to replace the iPhone’s battery; this is simply a normal process.
Solution: Simply swipe up briefly from the bottom of the screen with your thumb and reduce the screen brightness by 30 or 40 percent in Control Center. This will, first, drastically reduce power consumption; second, keep the display brightness permanently set to the level you just adjusted manually; and third, you’ll find that the reduced brightness on the iPhone screen is perfectly sufficient to read the display clearly even in direct sunlight.
All apps are constantly receiving data—such as messages and notifications—and most of them also use location services. This data needs to be received over the internet, which requires a strong signal and, in turn, an antenna that drains the battery depending on the transmission power. The screen makes things even simpler: at 100% brightness, your iPhone has a display that’s brighter than a car headlight from 40 years ago, and that also drains the battery quickly and heavily. The problem of an iPhone that’s too warm or even hot can be easily solved by reducing power consumption and taking the strain off the battery.