It may happen that the Samsung Galaxy S6 discharges completely. Say your smartphone is discharged to the extent that this automatically shuts down and no longer can be turned on. If you connect the Samsung Galaxy S6 now to a charger, then you can charge it as usual.
Now you might ask yourself the question:
Is it harmful to the battery if my Samsung Galaxy S6 is completely discharged?
The answer is:
Usually this doesn’t harm your Samsung Galaxy S6, in particular the battery. Because the Samsung Galaxy S6 has installed a protective mechanism to prevent a complete discharge of the battery's. This means that your battery has a remaining basic tension which is necessary that the battery does not have a long-term defective.
That's why it does not matter if your Samsung Galaxy S6 is sometimes discharged completely.
Nevertheless, we recommend you not to discharge it to 0% intentionally to have fun with your Samsung Galaxy S6 in a long term.