4 Things to Stop Doing When Charging Your iPhone

The most important thing to avoid when charging an iPhone is anything that generates excessive heat. The key word is “excessive” because heat generation is inevitable when charging a phone. Not all the current goes into the battery and the lost energy doesn’t just disappear into the ether. It becomes heat, destructive of lithium-ion batteries. Heat is also generated when lithium ions move between the electrodes during charging. So, because heat is inherent to the charging process, you don’t want to introduce more of it.

Excessive heat kills lithium-ion batteries because it accelerates the rate of thermal degradation and makes the battery’s internal chemistry unstable. Besides generating extra heat, you should also avoid other bad charging habits that will cause the iPhone lithium-ion battery to become unstable or short circuit. You need to make sure that you use its smart charging features, don’t run CPU-intensive tasks, and use certified chargers. If you follow these, along with good standard charging habits, like making sure the phone is well ventilated (not under a pillow or in a thick case), you’ll charge your iPhone safely for a long time.

Just because your iPhone can charge to 100% doesn’t mean you should. On the surface, this makes sense: the more charge the battery has, the more miles you get out of it. It’s not a car that “likes” a full tank because its fuel pump prefers to be completely submerged, rather than constantly sucking in air, and there is less space for fuel to evaporate, increasing fuel efficiency.

Lithium-ion batteries “hate” being refilled because it puts them under high voltage stress, which can accelerate chemical aging if left in this state for too long, causing them to lose capacity more quickly. Additionally, as they fill up, they become less effective at storing charge, with some of it leaking and turning into heat. If you’re using an iPhone 15 or newer, you can set a charging limit to ensure your iPhone doesn’t charge to 100%. Here’s how to do it:

1. Open Settings.

2. Tap Battery.

3. Tap Loading.

4. Set the desired load limit.

To avoid stressing the battery with high voltage, it is recommended to unplug the iPhone when it reaches 80%. At the same time, you should not let the battery drop below 20% to avoid the opposite: low voltage stress. This is called the 80-20 charging rule, but it’s not always practical to follow, especially if you’re used to charging your phone overnight. Your phone will eventually fully charge and remain in a high-voltage stress state for a long time, which is why overnight charging is not recommended. This is not because the battery will overcharge, as the common myth suggests, since modern lithium-ion batteries “know” when to stop charging once they reach 100%.

Luckily, iPhones have a feature called Optimized Battery Charging that will learn your charging patterns and delay charging the phone past 80%. This is especially useful for iPhones that don’t let you set a charging limit. Only when the phone determines that you are ready to use it will it start charging beyond this threshold, giving you time to disconnect it.

To enable Optimized Battery Charging on an iPhone, follow the steps below:

1. Open Settings.

2. Tap Battery.

3. Tap Loading.

4. Enable optimized battery charging.

Not all tasks you do on your iPhone are the same, as some are more demanding than others. One of the reasons why a smartphone can operate without built-in fans is that its system-on-chip (SoC), of which the processor is a part, does not consume much power under normal circumstances. This can change when you run demanding tasks, forcing it to draw more power from the battery to run them smoothly. But the more energy it consumes, the more heat it generates.

This is why your phone heats up more when you play “PUBG Mobile” than if you were replying to an email, even under normal circumstances. Since charging is already a process that generates heat, these intensive tasks that require a lot of energy will worsen heat generation and potentially lead to overheating. When your iPhone is charging, it’s best to leave it as is unless you want to do a quick, light task.

You can use any charger with your iPhone, but it’s probably best to use one designed specifically for it. Several problems can arise when using a charger from another brand, including constant overheating, port damage, and even frying the motherboard. iPhones are known for their longevity. For example, the iPhone 13 was the most popular iPhone in the United States in 2025, four years after its release.

However, uncertified chargers can shorten their lifespan or kill them because they may not be able to properly regulate the charging current. So, when you buy a charger for your iPhone, make sure it’s made by Apple or MFi certified (Made for iPhone) if it’s from a third party. These chargers are approved by Apple, providing assurance that you will not encounter any compatibility or security issues. Unless you purchased the charger directly from Apple, look for an MFi badge.

Nonetheless, you should evaluate the construction of the charger to ensure that it is of high quality. Otherwise, it could be a fake MFi badge. You can also use the accessory search function on the official Apple MFi program page. You can search by brand, model, or UPC/EAN code. These chargers look expensive, but they aren’t, with some like the Yaptech iPhone Lightning Fast Charger 20W or the Linocell iPhone 17 Charger 60W costing $19.99 and $18.97, respectively.