Recently rmy S7 battery has been acting up

[AC Question]

While I use the fast charge block, my phone will still charge slowley. Sometimes I will wake up at a lower percentage tHan before plugging it in. And last of all while I'm using my phone while on the charger, it will actually loose charge. All of my problems are occurring with low power mode ON!

 

[Rukbat]

It sounds as if something is using a lot of battery power. Look at the battery listing in Settings and see what it is. (Also, the phone is old enough that if you've constantly been draining it to lower than about 40%, it could have gone bad by now.)