This is the lesser talked about feature but basically for those who don't know..
"According to Motorola, it only takes the new Moto X (2nd Gen) 15 minutes reach an additional 8 hours of battery life. While you’d assume another 15 minutes would bring it to a full charge, that’s not exactly how Quick Charge 2.0 works. The quick battery boost is only provided when the device is completely empty, after which it brings charging to more normal levels (we’re sure this has to do with battery health)."
citation link
So you can only use Quick Charge when you're phone almost completely dead and you can't charge it for longer then 15 minutes in Quick Charge mode. It's assumed normal charging resumes after 15 minutes.
You also need to purchase a special Quick Charge charger for an additional $35
"According to Motorola, it only takes the new Moto X (2nd Gen) 15 minutes reach an additional 8 hours of battery life. While you’d assume another 15 minutes would bring it to a full charge, that’s not exactly how Quick Charge 2.0 works. The quick battery boost is only provided when the device is completely empty, after which it brings charging to more normal levels (we’re sure this has to do with battery health)."
citation link
So you can only use Quick Charge when you're phone almost completely dead and you can't charge it for longer then 15 minutes in Quick Charge mode. It's assumed normal charging resumes after 15 minutes.
You also need to purchase a special Quick Charge charger for an additional $35