The Samsung Galaxy S8 supports Samsung's proprietary quick charging scheme as well as USB Power Delivery for fast charging over the USB Type-C interface, allowing the phone to charge with third party chargers like the Anker PowerCore 13400mAh Nintendo Switch Edition PD Portable Charger. To observe how the Samsung Galaxy S8 performs with the Anker power bank through USB Power Delivery, we attached the phone on a dead battery to the power bank over the Type-C interface.
Upon plugin the voltage started off immediately on a 5 volts rail while the phone pulled initial current which gradually stepped up from about 0.2-1.5 amps within the first 100 seconds. After charging to around 7.8 watts (5.2 volts @ 1.5 amps), the phone began pulling quick changing current at repeated intervals to max out charging at around 10.8 watts (5.4 volts @ 2 amps). We can see that when actively used the phone drew power up to about 9.2 watts (5.4 volts @ 1.7 amps) from the power bank. When the phone went into sleep mode, it drew more power which averaged out to around 10.8 watts (5.4 volts @ 2 amps). Click here to download the trace captured by the GRL-A1 power analyzer to see more details.