Let's take a look at the 7.5W wireless charging test. (Test conditions: Qc2.0 charger 9V output, ambient temperature 29℃, iPhone8PLUS mobile phone, no air conditioning, no fan.)
In the first 10 minutes, it will jump to 7.5W fast wireless charging, and then it will be maintained at 5W charging, and it will take more than 4 hours for the iPhone8PLUS to fully charge.
Look at the 5W wireless charger test situation: (test conditions: Qc2.0 charger 5V output, the ambient temperature is 29℃, do not open the air conditioning, do not open the fan. Fully charged in 2 hours 20 minutes.
This difference is reflected in the length of charging time, because the Apple 5.7 watt output current is 1.5a, and the Apple 5 watt charger, its output current is 1a. When charging the mobile phone battery input, the 17.5 watt will be 50% faster than the 5 watt mobile phone charger.