A SamMobile writer reported seeing his battery sink from 10% to 5% in seconds, and his experience has been echoed by several Reddit users.
Reddit user ToonTonic reported losing nearly 50% of their battery charge in an hour with no apps open.
Another Reddit user reported their battery dropping from 10% to 4% in 3 minutes.
It's not just this Android 9.0 update that has affected battery life negatively, however.
Samsung will possibly look to fix these battery issues in January 2019 as part of its expected patching cycle.
