Apple is making it easier to replace your iPhone if it randomly shuts off with 30% battery
Some iPhones are shutting off when their batteries say they have about 30% left. When they're plugged back in, they quickly jump back to 30% battery - so they weren't out of power.
It's a real problem! Anecdotally, several BI staffers have encountered it, and there are pages-long threads on Apple forums about the issue.
Apple has addressed the issue. In November, Apple announced a free battery-replacement program for "unexpected shutdown issues." Apple suggests it's a hardware problem, and it only affects a "very small number of iPhone 6S devices" produced in late 2015.
So if you're having the issue, Apple might not cover you, if your phone isn't eligible. On Thursday, Apple introduced a tool to its webpage so you can figure out if your phone is covered without visiting an Apple Store.
Simply visit the page, and plug in your serial number. If you don't know your serial number, you can find it through Settings > General > About.
But if you're having the issue on an iPhone besides a 6S, sorry, but Apple can't help you at this time.