By supporting Qualcomm Quick Charge 4+ technology, the Xiaomi Mi 8 can charge not only with USB Power Delivery 3.0 and Qualcomm Quick Charge 3.0 based chargers but also the USB Power Delivery 2.0 based Anker PowerCore 13400mAh Nintendo Switch Edition PD Portable Charger over the USB Type-C interface.
Using a USB Type-C to Type-C cable we plugged in the Xiaomi Mi 8 to the Anker PowerCore 13400mAh Nintendo Switch Edition PD Portable Charger and observed USB Power Delivery charging. Current was pulled immediately along a 5 volts rail starting voltage by the Xiaomi phone while on a fully depleted battery. As the current lingered at about 1 amps, the phone drew initial power of around 5.1 watts (5.1 volts @ 1 amps) from the power bank. Once the battery has charged for about 40 seconds a hard reset happened where the phone trickle charged for a bit. This led to an increase in voltage to a 9 volts rail with higher current being pulled allowing charging at around 16.2 watts (9 volts @ 1.8 amps). This power level is also close to that supplied by the original Xiaomi 18W QC3 charger which shows that the Xiaomi Mi 8 can support USB Power Delivery 2.0 just as well as Qualcomm Quick Charge 3.0 for charging.
Click here to download the trace captured by the GRL-A1 power analyzer to see how charging looks like between the Anker power bank and the Xiaomi phone.