Photos (Background Activity) using all of my battery
I've had this problem for about a month where my Photos app is using 20% to 30% of my battery daily and 25% to 35% weekly with "Background Activity". I've contacted Apple Genuis twice about it and they have no clue what the problem is and I've sent full diagnostic tests in and still have no clue. I've restored my phone and always quit Photos app in multitasking even though I don't use it that much, I use other apps more than I use Photos but it still uses twice the battery as my main apps. I turned off most of my apps to have access to my photos and don't have iCloud Photo Share or Stream on. I can't find the Photos app in the background app refresh settings to turn off background activity so how do I stop it from using all of my battery? Please help!
iPhone 6 Plus, iOS 8.1.2, 64GB, AT&T