Chosen Solution
After charging my battery fully, by mid day I have to charge the battery again. For example, I left home at 9am with 100% Battery and by 1.45pm, my battery was at 17%
It might be you’ve got a rogue app that’s keep the radio on all the time trying to update. Have a look in Settings > Battery > app usage to see if there’s something that’s abnormally high. Otherwise, yes, it could well be an old battery.
