I'm running into issues with my battery draining quickly (iPhone 6s with iOS 11) and it appears that Photos is the culprit (based on % battery use) presumably from uploading photos to iCloud Photo Library (with ~150k items).
I can manually 'Pause Updates' by going into Photos. Updates are also paused when in Low Power Mode — both of these are helpful. However, when I plug in the phone to charge and it gets back to 80%, Low Power Mode turns off and iCloud Photo Library updates resume, and my battery quickly drains again.
It could be that the battery just needs to be replaced. The capacity is above 80% and the iPhone reports that the batter is ok.
Is there a way to to configure Photos to only update iCloud Photo Library when it is plugged in and not to update when it is on battery power?