GTrusted

To see if you can use a third party charger like the USB Power Delivery based RAVPower Xtreme 26800mAh Portable Charger with Type C Port + 30W Type-C AC Charger to charge certain Windows based Thunderbolt 3 PC's like the Spectre x360 (2nd Generation 2017), we will see how they perform here. We will use the battery portion of the charger to charge the USB Power Delivery enabled Spectre x360 (2nd Generation 2017) over its USB Type-C connector. 

The RAVPower Xtreme 26800mAh Portable Charger with Type C Port + 30W Type-C AC Charger battery begins USB Power Delivery negotiations by declaring that it offers only a single 15 watts (5 volts @ 3 amps) power profile to the Spectre x360 (2nd Generation 2017). The notebook then requests that 15 watts (5 volts @ 3 amps) from the battery which it accepts.

The charger battery later advertises not only the 15 watts (5 volts @ 3 amps) it initially declared but also four other power profiles: 27 watts (9 volts @ 3 amps), 28.8 watts (12 volts @ 2.4 amps), 31.5 watts (15 volts @ 2.1 amps), and 30 watts (20 volts @ 1.5 amps). The Spectre x360 (2nd Generation 2017) then requests to pull 30 watts (20 volts @ 1.5 amps) which is accepted by the charger battery.

However, soft resets eventually terminates charging but the charger battery resumes communication after some time.

When the Spectre x360 (2nd Generation 2017)'s battery is well charged, we can see that charging happens at 30 watts (20 volts @ 1.5 amps). 

We can confirm that the RAVPower Xtreme 26800mAh Portable Charger with Type C Port + 30W Type-C AC Charger's portable battery is able to properly charge the Spectre x360 (2nd Generation 2017) using USB Power Delivery over the PC's USB Type-C port which supports Thunderbolt 3, USB 3.1 Gen 2, DisplayPort, and USB Power Delivery technology.