Apple sources the CPUs for the iPhone 6s and 6s Plus from two different companies: Samsung and TSMC. But the chips are different. According to this Engadget Public Access article, readers on Reddit and MacRumors have run tests, and it turns out that the TSMC chip provides about 2 hours more battery life than the Samsung version.
You can check your iPhone’s CPU by installing the free Lirum Device Info Lite app from the App Store (there are probably other apps that can provide this info too). After you launch the app and dismiss the ad, you’ll see something like this:
The Model section tells you which processor you have.
- N66AP (6s plus) or N71AP (6s) – Samsung chip
- N66MAP (6s plus) or N71MAP (6s) – TSMC chip
I have the TSMC chip, and my battery life has been fine. But I noticed yesterday a review in The Guardian that says:
Apple has chosen weight and thickness over battery life, which is a poor choice. Your experience may vary, but I suspect you will have to charge the iPhone 6S twice a day.
I was surprised when I read that review, because my battery life has been exemplary. If some models of the iPhones 6s have 2 hours less battery life, I would think that Apple is going to need to recall the phones with the Samsung CPU.
Update: Apple has said that battery performance in real-world conditions result in only a 2-3% difference in battery life.