I am also having problems with my note 4 with the fast charge.. my phone will barely charge the battery to 70 percent overnight with the phone off...
had it 2 weeks now called sprint went to sprint store i got it from they said they fixed it came home plugged in charged for 2 hours went from 40 percent to 53 percent

called sprint they told me they will go through my warranty haaaa gave them a piece of my mind ..
got transferred to samsung to get it warrantied out.. its 2 weeks old cant they jusr freaking exchange the damn thing for a new one hungup on samsung they want me to send them my phone and be without it for 2 weeks while they diag and fix..
go to another sprint store they checked it out and said the charging port is bad and will order me another one ... such a pain in my **** today talked to sprint 5 times and went to 3 stores phone is 2 weeks old
and i believe my gf who got the same phone same day as mine her phone is taking 5 hours to fully charge i think hers is taking a dump too