FP2 Battery health and duration?

I’m closing this so we don’t have to many open threads about the same topics.

For general discussions please continue here:
https://forum.fairphone.com/t/fp2-research-on-power-consumption-in-idle-and-stand-by-to-prolong-battery-duration/12947?u=paulakreuzer
or here:

For problems with the battery here:

And for problems with charging here: