I work on the manufacturing side of USB-C hubs, and there is one complaint that comes back so consistently that it is worth explaining properly: the laptop is plugged in, through a 100 watt hub, and the battery is still going down.

The hub is not lying to you. It is keeping some of the power for itself, and it is doing that because it has to.

Here is the arithmetic. A hub advertising 100 watt passthrough takes 100 watts in from your charger. It then reserves somewhere between 12 and 20 watts to run its own electronics, to convert the DisplayPort signal into HDMI, and to power the peripherals you plug into it.…