GTrusted

The Samsung Galaxy S8 is supplemented with the DeX Station that offers USB Power Delivery charging in addition to its own proprietary quick charging scheme as well as USB data and HDMI connectivity for the phone over USB Type-C. The DeX Station can support either Samsung's own Adaptive Fast Charging chargers or other USB Power Delivery chargers like the Google 18W USB-C Power Adapter.

We first insert the Samsung Galaxy S8 into the DeX Station and then use the DeX to connect to a HDMI TV. We then plug in the Google 18W USB-C  Power Adapter to the DeX's USB Type-C charging port using a USB Type-C to Type-C cable. Using the Granite River Labs  GRL-USB-PD-A1 app, we observe how charging happens between the DeX Station and the Google 18W USB-C Power Adapter over USB Power Delivery.

From the USB Power Delivery negotiations, we see initially the Google 18W USB-C  Power Adapter repeatedly offers 15 watts (5 volts @ 3 amps) and 18 watts (9 volts @ 2 amps) to the DeX Station when the Samsung Galaxy S8 is docked and connected over HDMI.

The DeX Station first requests only 10 watts (5 volts @ 2 amps) to which the Google charger accepts.

After requested by the DeX to display its source capabilities, the Google 18W USB-C  Power Adapter again repeats the initial 15 watts (5 volts @ 3 amps) and 18 watts (9 volts @ 2 amps) power profiles.  

The DeX Station then takes this opportunity to request and establish the highest 18 watts (9 volts @ 2 amps) power contract with the Google charger.

We further observe that the DeX Station starts pulling current below 0.5 amps at 5 volts after plugin while initially attached with the Samsung Galaxy S8. The DeX then pulls higher current at about 1.1 amps as the voltage goes up to 9.1 volts after requesting 18 watts (9 volts @ 2 amps) to support the Samsung phone. The current pulled later increases slightly to about 1.3 amps for the DeX to eventually draw around 11.8 watts (9.1 volts @ 1.3 amps) of charging power. This shows that the DeX actually consumes more power used to support the HDMI port connected to the TV.

By comparison, without using HDMI, 11.8 watts is slightly higher than what the DeX Station gets with the Samsung Adaptive Fast Charging Charger as reviewed here, but is similar power as when used with the Apple 61W USB-C Power Adapter in this review, both also having the Samsung Galaxy S8 docked onto the DeX.

The DeX Station does work well over USB Power Delivery with the Google 18W USB-C  Power Adapter, which comes handy if you don't have a Samsung charger and need a quick power source.