I have just updated my watch yesterday to the latest firmware version 14.13. Battery level was at 70% when I went to bed. This morning it is at 45%. It went down in 9 hours while I was sleeping. And no, PluseOx is turned off, so it is not because of that. I did an Indoor Climb activity right before I went to the bed, if that matters. I also did a soft reset after the firmware update.