Drums a delicate subject, especially when we are talking about iPhones.
The Apple smartphone is designed to retain up to 80% of its original capacity for 500 full charge cycles. Recently AppleCare + started to cover batteries that retain 80% or less of their original capacity. As Brazilians, we do not yet have AppleCare + available in our country, this coverage is only valid for the device's one-year warranty period. But how to identify whether your battery is defective or not, retaining less than 80% of its capacity?
Until then, the best known way to get this information was using the coconutBattery app for OS X. Although it is an app for Mac, just stick your iPhone on your computer to also be able to view the device's battery information. That is, it does not solve the problem for those who have an iPhone and a PC, for example.
Enter the app Battery Life.
It is a new application for iOS, universal (that is, compatible with iPads and iPhones / iPods touch) and free, which shows the information of the battery life in a simple and direct way.
In addition to showing the level of battery degradation, it is also possible to view projections of battery life times for the most diverse purposes (3G conversion, 3G / 4G / Wi-Fi navigation, video / audio playback, etc.). There is also the option to check the raw data of the battery, such as charge, capacity, voltage, cycles, temperature, charge current, charge state and maximum charge current.
In my tests, battery degradation was between 1% and 4%. In comparison, coconutBattery says it varies between 1% and 2% (meaning the data is not very different). Both also say that the battery of my iPhone 6s has 99 cycles. Although it is not something exact, it is a good reference for you who have some doubts about the performance of your battery.
(tip from Miguel Dornaes)