To see how well the Xiaomi Mi 8 performs over a Qualcomm Quick Charge 4+ platform, we linked up the phone with the third party Portway 60W USB-C PD and QC4+ Charger and observed QC4+ based charging. While entire charging summed up to about 115 minutes, it was unexpectedly slower than the 110 minutes taken using the Mi 18W QC3 Charger that ships with the phone (more details here). Rather charging could have been faster given the more high-end QC4+ charging by the Portway charger.
Note the Qualcomm Quick Charge 4+ technology includes USB Power Delivery 3.0, PPS (Programmable Power Supply), and Qualcomm Quick Charge 3.0 support over the USB Type-C interface.
Starting from a fully drained battery on the Mi 8, we connected the phone to the QC4+ enabled USB Type-C port on the Portway 60W USB-C PD and QC4+ Charger. The phone initially drew power close to 18 watts but a few minutes later it kept on using Augmented PDO's to request the charger to step up from 5 volts to near 10 volts as the current level dropped to almost half and rapidly changing. When the voltage rose to almost 12 volts, the current became more settled to level out charging at around 14 watts. After 50 minutes later, the power charging reset resulting in both voltage and current to decrease for charging to drop to around 3.5 watts and further down to about 1 watt when reaching full charge on the battery. Click here to download the trace captured by the GRL-A1 power analyzer to see more details on the entire charging cycle.