I think I have solved the charging problem with the Samsung s7. I would stop at 53% and go no father. I allow it to discharge to 0%. The I charged it again and this time it stopped at 73%. Then discharged it to 0% again. And recharged it again, and this time it went to 100%. It seems like that the battery need to be exercised up and down to get full activation of the cell in the battery. The old wet cell batteries would sulfate and act this same way.
(plates would become hard and not be able to accept the electrolyte).
Don't know if this is the case but it fixed my problem with the phone not being able to reach 100% charge.
Don R