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The  SoftBank SELECTION USB Type-C Fast Charging AC Adapter can serve as a replacement power supply to charge various USB Type-C devices including non-Qualcomm Quick Charge enabled phones like the Samsung Galaxy S8. Let's see how well the SoftBank charger performs with the Samsung Galaxy S8 phone which supports Samsung's proprietary quick charging scheme as well as USB Power Delivery for fast charging over the USB Type-C interface. 

Plugging in the SoftBank SELECTION USB Type-C Fast Charging AC Adapter to the Samsung Galaxy S8 while the battery is fully depleted, we can see from the Granite River Labs GRL-USB-PD-A1 software that the phone charges at around 6.5 watts (5 volts @ 1.3 amps) when it is actively used. When the phone goes into sleep mode, it draws more power averaging around 10.8 watts (9 volts @ 1.2 amps) with frequent current spikes in between.

The Samsung Galaxy S8 gets about the same 10.8 watts (9 volts @ 1.2 amps) in similar fashion when powered by the Samsung Adaptive Fast Charging Charger as seen in this review.