@AlbertHall
There are other topics where this issue has been addressed, the only viable option is to root the phone and download an app.
Because this topic mentions 80% it may appear a different issue, it isn’t, maybe this topic can be merged with
Another issue is that Fairphone have, no doubt, taken advice from the battery manufactures, and the charge rate is set for optimal user experience ??. The battery is guaranteed for a year.
If you root the phone and mess with the settings Fairphone have no way of knowing what you may do and the warranty would be void.