This is common after Android updates. Normally battery use goes back to normal after some time. A lot of background process run after update, for example all media files will be reindexed. If you have a lot of files, this will take some time. If battery use does not return to normal after a couple of days there may be a conflict between an app and the update - sometimes this can be diagnosed from the per-app battery use estimations somewhere in the settings menu.