The so-called “40-80 rule” from Apple is a recommended guideline for managing the battery of devices such as iPhone, iPad and MacBook. The Apple indication suggests keeping the battery life of the device between 40% and 80% most of the time, if possible, in order to maximize the battery life in the long term. The advice is based on the typical behavior of lithium-ion batteries, commonly used in most electronic devices.
Apple invites you to avoid fully charging the device up to 100% and letting it completely discharge: these cycles complete with load and unload can contribute to faster battery deterioration. Periodically, such as once a month, Apple suggests fully charging your device up to 100%. This process can help calibrate the battery and keep the charge level display accurate.
The 40-80 rule and Apple’s indications are applicable in the case of any device you use lithium ion battery, even from different manufacturers. In fact, we also talked about it in the article in which we explain what to do if the battery on Android runs out quickly.
The 80% battery charge limit is automatically applied on iPhone 15
Following the guidelines briefly outlined in the introduction can help preserve the battery life. However, many people find it more practical to use their devices without worrying too much about rigorous maintenance charge between 40% and 80%.
So Apple, like other manufacturers, have developed software algorithms that take care of adapting the charging process of battery, slowing it down significantly above 80%. It’s the concept of adaptive chargingespecially useful when you leave your smartphone charging all night.
The news is that the owners of iPhone 15 and iPhone 15 Pro can now limit the charging of their phones to no more than 80%. It is not mandatory but according to Apple, as is already known, activating the function can help to attenuate “battery wear and improves battery life by reducing the time your iPhone spends fully charged“.
iPhone 8 and later already support what Apple calls “Optimized Charging.” The difference compared to the solution introduced with the iPhone 15 is that Optimized charging It works by limiting the battery charge to 80% when the iPhone is inactive (usually in the middle of the night). The new feature of recharge to 80% (limited to iPhone 15s for now) doesn’t try to be as smart and simply enforces the limit throughout the day.
Why Apple doesn’t bring the “charge limiter” to previous generation iPhones
Presumably there’s nothing stopping Apple from sending a software update on previous generation iPhones to enable the “charge limiter” at 80% throughout the day. On the other hand, the intelligent battery protection that is activated for example at night is already present: therefore the reasons for the choice are not clear.
A feature that uses a very similar recipe to ensure longer battery life is available on most smartphones, for example Samsung Galaxy equipped with One UI version 4.0 and Android 12 or later, both products released in 2021.
They are Reddit there is an endless discussion containing suggestions on how Apple could further improve the functionality. However, everyone’s hope is that the 80% charge limiter can also be brought to previous iPhones. A further step that would help reduce the volume of electronic waste, thanks to batteries that last longer and need to be replaced less frequently.