I'm wondering if anyone has seen this with their iPhone 6 Plus. In recent weeks, the battery on my iPhone has been performing very erratically. It definitely does not last as long as when the first phone came out. But stranger still, the battery percentage will drop dramatically after reaching the 50% mark or so, to a red zone level (sub 20%). Today I was using the phone and it was showing 53% when the screen suddenly went dark. When I looked closely at the screen, it showed an empty battery icon asking me to plug in a cable. When I plugged the cable in, the batter jumped back to 50% and I was able to Cronus using the phone unplugged. When I took it into the Apple Store, they tested the battery and didn't find anything wrong. They asked me to do a clean install of iOS which I did but I still have this issue. Being an iPhone 6 Plus, it is outside of warranty. Anyone seen something like this before ?