The Plugable USB-C 3-Port Hub with Pass-Through Charging has the ability to pass-through charging from other USB Power Delivery chargers to a computer or phone. Let's see how well it works trying to pass-through power from the dodocool 30W USB Type-C PD Charger to the HP Chromebook 13 G1.
Using software from Granite River Labs, first we look at the USB Power Delivery negotiation between the dodocool 30W USB Type-C PD Charger and the Plugable USB-C 3-Port Hub with Pass-Through Charging.
First we see that the dodocool 30W USB Type-C PD Charger offers 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), and 30 watts (15 volts @ 2 amps) to the Plugable USB-C 3-Port Hub.
The Plugable USB-C 3-Port Hub then initially requests 5 volts @ 3 amps from the dodocool 30W USB Type-C PD Charger.
A discovery process starts where the dodocool 30W USB Type-C PD Charger asks to discover what it's talking to.
The Plugable USB-C 3-Port Hub then provides information about itself to the dodocool 30W USB Type-C PD Charger.
After the dodocool 30W USB Type-C PD Charger understands who its talking to, it then announces support of 20 volts @ 1.5 amps as well.
The Plugable USB-C 3-Port Hub then requests 5 volts @ 3 amps again from the charger.
The dodocool 30W USB Type-C PD Charger provides this power but then the Plugable USB-C 3-Port Hub again requests 5 volts @ 3 amps again from the charger which again provides the power requested.
After the Plugable USB-C 3-Port Hub understands that it needs to provide more power to the HP Chromebook 13 G1, it then requests 15 volts @ 2 amps (30 watts) from the dodocool 30W USB Type-C PD Charger.
If we now look at the transactions between the Plugable USB-C 3-Port Hub and the HP Chromebook 13 G1, we first see them swap power provider and consumer roles.
The Plugable USB-C 3-Port Hub then announces the supported power profiles that it passing through from the dodocool 30W USB Type-C PD Charger. Note that the currents are lower than what the dodocool 30W USB Type-C PD Charger provides to the Plugable USB-C 3-Port Hub (reduced by 12.5 watts for the 5 volt rail, and 5 watts for the other rails due to the power consumer by the hub or provided to the Type-A ports downstream of the hub).
The HP Chromebook 13 G1 initially requests 5 volts @ .5 amps.
The HP Chromebook 13 G1 then requests 15 volts @ 1.67 amps (25 watts) from the Plugable USB-C 3-Port which is passing it through from the dodocool 30W USB Type-C PD Charger.
The HP Chromebook 13 G1 also declares its own power capabilities at the end of everything.
By supporting USB Power Delivery, the Plugable USB-C 3-Port Hub with Pass-Through Charging is able to successfully pass through a complex USB Power Delivery negotiation sequence and can intelligently pass-through power from the dodocool 30W USB Type-C PD Charger to the HP Chromebook 13 G1.
Other hubs like the Marsboy 2 USB 3.0 Type-C Charging Hub don't properly support Power Delivery which makes it challenging to work with external USB Power Delivery based chargers.