[iMore.com]

The iPhone 6s and iPhone 6s Plus has a slightly smaller battery than the previous generation—blame the Taptic Engine for horning in on its space—but also great processor and radio efficiency and software in iOS 9 designed to extend power savings longer than ever. The result should be about the same this year as last. But if that's not the case, if your iPhone 6s or iPhone 6s Plus isn't lasting as long as you expect, here's what you can do about it!

Full story from the iMore Blog...

[Just_Me_D]

This quote stands out the most for me.

"The single biggest cause of battery life problems is restoring from backup and not setting up as a new iPhone. Yes, setting up as a new iPhone is a pain but, if you have significant problems that nothing else can fix, setting up as new can also be the solution. It's the nuclear option, no doubt about it. You will have to set up absolutely everything again, and you will lose all your saved data like game levels, but in most cases your battery life will be better than ever."

~Rene Ritchie