GTrusted
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 Belkin USB-C Car Charger + Cable to the Apple MacBook (Early 2015).
Using software from Granite River Labs, first we look at the USB Power Delivery negotiation between the Belkin USB-C Car Charger + Cable and the Plugable USB-C 3-Port Hub with Pass-Through Charging.
First we see that the Belkin USB-C Car Charger + Cable offers 15 watts (5 volts @ 3 amps) and 27 watts (9 volts @ 3 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 Belkin USB-C Car Charger + Cable.
The Belkin USB-C Car Charger + Cable 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.
If we now look at the transactions between the Plugable USB-C 3-Port Hub and the Apple MacBook (Early 2015), the Plugable USB-C 3-Port Hub then announces the supported power profiles that it passing through Belkin USB-C Car Charger + Cable. Note that the current is lower than what the Belkin USB-C Car Charger + Cable provides to the Plugable USB-C 3-Port Hub due to the power consumer by the hub or provided to the Type-A ports downstream of the hub.
The Apple MacBook (Early 2015) only requests 5 volts @ .5 amps from the Plugable USB-C 3-Port Hub which doesn't exactly allow you to charge quickly but that's all the power that is available.
The Apple MacBook (Early 2015) also declares its own power capabilities at the end.
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 Belkin USB-C Car Charger + Cable to the Apple MacBook (Early 2015).
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.
