Where is this battery draining code from?

The battery draw of my bangle.js is weird. It would use 8~9% everyday
for a couple days, then suddenly lose all charges in one night. Often
I went to sleep with 50~70% battery and wake up with a dead watch.

Is there a way to log battery percentage overtime? And is it possible
to figure out what is drawing the most power at any given time?

@yshui in this conversation.

That sounds at least somewhat similar to my experience.

Could you copy/paste installed apps from the app loader's 'More...' tab? Maybe we can see what apps we have in common to narrow down suspect apps.