I have an iPhone 6s that I bought in late 2015. By late 2017 I was getting horrible life from the battery so I jumped at the chance to get a replacement from Apple (1000 baht here in Thailand or about US$30) in early 2018. By late 2018 the replacement battery was already performing quite poorly; so poorly that I started routinely putting the phone in Low Power Mode and carrying along a power bank if I was going to be away from a charger for any length of time. Currently the iPhone 6s says that the battery is able to charge 90% of capacity and capable of Peak Performance. However, Coconut battery says that the phone is only able to charge to 77.4% of design capacity. (Wow. Why so different?) I have made huge efforts to reduce battery usage by limiting Background App Refresh to only those apps in which it is either essential or very important. I have also limited Locations Services in most apps to when the app is in use. And, frankly, I don't use the phone that much. I have an iPad which I use for most of my reading, email, web surfing, etc. I don't make or receive telephone calls. I send a few Messages to my wife and daughter during the day. I take a few photos. I listen to music for a couple of hours per day. If I am away from WiFi I listen only to music already downloaded to the phone. The other day I took my phone on a 65K bike ride. I was using the Apple Workout app on my Apple Watch to track the ride. (I know that this hands off Location Services duties to the phone.) I put the phone in Low Power mode. I only used it four times: Twice to let my wife know where I was. Once to check my location on Google Maps (no navigation) and once to look up the meaning of a Thai word. After three and a half hours my phone was down to 55%. I didn't use it again until later in the day by which time the battery was at 45% and still in Low Power Mode. I then used it to read a Kindle book while sitting by the pool. (Yeah, I had to turn the brightness up to see the screen in the bright sunlight.) In ten minutes the battery had gone from 45% to 25%. Still in Low Power Mode. So, should I get another new battery or would that just be throwing good money after bad?