For the last 5 years I have been using an iPad Mini 2 to surf the web with Chrome on the couch. Even with a 5 year old battery, I would be able to do it for a long time, often not charging it for 3 days or more. That iPad is now gone (RIP) so I started using my iPhone 6S more for web surfing. The phone is 3+ years old but the battery is relatively new. I had a new battery installed at the Apple store less than a year ago for a discounted price ($25 I believe) due to some issue that you probably already know about. Right now the Battery Health says that it is at "Maximum Capacity - 97%" and "Peak Performance Capability". So here is the problem: I can literally watch the battery percentage decrease as I use the iPhone to surf the web. It will go down faster than 1% per minute of use. Sometimes even faster. Last night I had 64% when I sat on the couch at 9PM and with limited web surfing while watching TV the phone was dead by 11PM. I don't remember it being like this over the last 3 years, it seems to be only over the last few months. Could this be some type of software change?