Need an update for power consumption issue. Many people think this issue comes from the power hungry CPU (Exynos 9810), compare to US Version (S9 Snapdragon 845), Snapdragon is more efficient, faster ,and more smooth gaming experience. Please release an update soon as possible, thanks.
It was said that the issue was on the kernel side. A security patch from few months ago (Probably July or August) was released and some users have reported that the battery life has significantly increased, especially in standby times.
Make sure you update your phone to the newest patch. Try to uninstall apps that you don't use.