I've had my S9 about 18 months and in the last week the battery is draining rapidly.  For example, at 6.30am it was 100% by 10:00am it was 1%.  I only use it for browsing, emails etc so not a lot.  I was advised from an android forum to 'clear cache partition'???  I did this and it has improved slightly in that I turned it on around 7.30 am this morning at 100%, its now 13:00 and it's at 10%.  It's really annoying.    Can anyone help, in sim