Apple, which tapped two different manufacturers for the A9 chips of its iPhone 6s and iPhone 6s Plus, has been made to explain reports that the iPhone 6s units equipped with the TSMC chips have a much longer battery life compared to the models equipped with the Samsung chips.

Various tests have been carried out to test the battery life of the TSMC models and the Samsung models, with all the tests confirming the better performance of the iPhones outfitted with the TSMC-made chips.

In a statement released by Apple, it said that through the company's own test sessions and data gathering, the difference between the performances in battery life between the devices is just between 2 percent and 3 percent. The difference, Apple claims, should not be noticeable during real-world usage of the iPhone.

According to Apple, the tests being run to compare the TSMC model and the Samsung model by putting them under heavy workload for hours until the depletion of the battery are not a good representation of real-world usage, as the time that the processor spends on such a high-performance state is unrealistic. As such, the tests are misleading in measuring the real-world battery performance of the devices.

Apple has a point in calling out the legitimacy of the battery life tests to compare the two models, as the tests turn on all the functions of the devices and checks to see how long they will last, which is something that users will not do over the course of their everyday life. On the other hand, the data that Apple has gathered come from anonymous diagnostic data that iPhones send to Apple, which is data that covers how users normally use their iPhones.

The battery life of iPhones is always under scrutiny, and for the new models, the battery life has often been cited as similar to the performance of last year's iPhone. For Apple, however, it is an achievement to maintain the battery life with the increased performance from the A9 chip.