iPhone 6S Plus 128gb Has anyone else experienced this issue: Battery with optimised settings (no back ground refresh, siri off, backlight 10%, most locations and notifications off, background location services off except find my phone) and minimal usage (texting, web browsing, calling, podcasts) and on wifi mostly lasting only 6 hours usage and 15 hours standby? I had almost two day battery with the 6 Plus and same settings/usage. Like 14hour usage and 32 hr standby. The main problem is when I get into the red zone: 20% or less battery the iPhone shuts down and has the please plug me in sign as if it has no battery. Plugging it in, it says 13% or 19% as when I last had it on before it decided to shut off and act like it had no battery. It does this in low power mode too. If it is a common problem let me know if there is a fix. Trying to save the hassle of driving to "apple". It's a real issue because I need my phone in the hospital and one of the times I was low on battery it switched off I was getting a call from the consultant.