I've been playing with battery management on this laptop (HP 17-cp1035cl). If you'll remember from my previous posts, none of the traditional methods of limiting battery SOC work on this machine.
I'm not sure what I changed, as I didn't catch this until after it'd already happened, but somehow the charging light turned from white to orange, and the battery charge descended from 100% to 93%. It stayed there for many hours.
Then I had to reboot, and it went back to 100%, and now I can't get it to repeat the behavior. {frustrated} 
I'm going to try to retrace my steps, more slowly this time.