Should you really limit your iPhone’s charge to 80%?

We recently told you about it, limiting the charge of your iPhone to 80% would extend the life of the battery. A journalist tested this feature for a year on her iPhone 15 Pro Max, with encouraging but not spectacular results. New feedback is now enriching the debate and tends to confirm the benefit of this practice.

A German study examines the question

The German site Macwelt conducted a survey among its readers who owned an iPhone 15. They asked them for screenshots showing the state of health of their battery after a year, and whether or not they limited charging at 80%.

By comparing the data, one observation emerges: batteries seem to degrade faster when charged to 100%. To support these results, the German site then carried out a statistical test.

Statistics confirm intuition

To find out if the difference was significant, Macwelt used a test called the T test. It is a method that allows two groups to be compared: here, those who limit the load to 80% and those who go up to 100%.

The test calculates a value called « p-value ». It designates the probability that the difference observed between the two groups is due to chance. The lower the p-value, the more certain we are that the difference is real and not just a coincidence. It is generally considered that a p-value less than 0.05 (i.e. 5%) is sufficient to conclude that the difference is statistically significant.

Macwelt took the test twice. First with all the data (102 iPhones), then excluding lightly used batteries (less than 140 charge cycles). And in both cases, the p-value was less than 0.05. This means that there is less than a 5% chance that the difference in battery degradation between the two groups is due to chance. We can therefore say with confidence that limiting the charge to 80% helps preserve the battery in the long term !

However, should you rush to activate this option on your iPhone? Not necessarily. If you change your smartphone every year, the difference will be minimal. On the other hand, if you keep your device for several years, it may be worth it, provided of course that your daily use does not require 100% autonomy. As always, it’s about balancing comfort and durability.

On this subject, do not hesitate to read or reread our 6 tips to increase the life of your battery.