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The Lenovo ThinkPad X1 Carbon (5th Gen 2017) is a more premium notebook PC from Lenovo that supports USB Power Delivery charging protocol via its two Thunderbolt 3 enabled USB Type-C connectors. The Thunderbolt 3 ports can be used for charging in both directions over USB Power Delivery, which means they are able to charge other USB Type-C devices as well as the Lenovo notebook itself. Other than charging, the Thunderbolt 3 ports also support Thunderbolt 3 (40 Gb/s), USB 3.1 Gen 2 (10 Gb/s), and DisplayPort 1.2 to connect with 4K@60hz displays.

The Lenovo ThinkPad X1 Carbon (5th Gen 2017)'s included AC power adapter is 65 watts based which offers the following USB Power Delivery profiles- 65 watts (20 volts @ 3.25 amps), 45 watts (15 volts @ 3 amps), 18 watts (9 volts @ 2 amps) and 10 watts (5 volts @ 2 amps) through its USB Type-C cable connector. When plugged in to a Thunderbolt 3 port on the Lenovo notebook, we observe how USB Power Delivery protocol transactions happen over charging using GRL-USB-PD-A1 analyzer software from Granite River Labs. 

We can initially see the Lenovo 65W USB-C Charger starts to communicate USB Power Delivery with the Lenovo ThinkPad X1 Carbon (5th Gen 2017) at 18% battery level by listing 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), 45 watts (15 volts @ 3 amps), and 65 watts (20 volts @ 3.25 amps) power capabilities. Note that the 15 watts (5 volts @ 3 amps) and 27 watts (9 volts @ 3 amps) being declared don't actually match the 18 watts (9 volts @ 2 amps) and 10 watts (5 volts @ 2 amps) given on the charger's casing.

The Lenovo ThinkPad X1 Carbon (5th Gen 2017) goes ahead to request the highest 65 watts (20 volts @ 3.25 amps) power option from the charger which it then accepts.

We then observe a series of Vendor Defined Messages occurring over which the charger initiates Discover SVIDs, Discover and Enter Modes, Unstructured VDM, and Exit Mode with the notebook. 

On a 18% charged battery, we can see in the first 10 seconds the Lenovo ThinkPad X1 Carbon (5th Gen 2017) starts off pulling current at about 20 volts over initial power request and Vendor Defined Messages while the notebook is turned on upon plugin. The notebook then pulls higher current to eventually charge by drawing an average 52 watts (20 volts @ 2.6 amps) power in between 2.4-2.8 amps bouncing current.

As expected, the Lenovo ThinkPad X1 Carbon (5th Gen 2017) works well with its own Lenovo 65W USB-C Charger using USB Power Delivery although we didn't observe charging to reach max 65W from the above negotiations.