Guide
You plug the same charger into the hub instead of the laptop, and the battery starts losing ground during meetings. Nothing is broken. A hub spends part of the power it receives, and three other limits sit between the wall and your battery.
What reaches the laptop is the charger's real output, minus what the hub keeps, minus what everything attached to the hub is drawing — and the whole thing is capped by the weakest cable in the chain. A 65W charger feeding a hub that states 87W-from-100W passthrough, with a portable SSD attached, can leave a 65W laptop charging slower than it discharges under load.
This is why the fix is almost never a better hub. It is a charger with headroom: size it above your laptop's requirement by the hub's stated overhead, and check the cable can carry it.
| Cause | What you see | What to do |
|---|---|---|
| The hub reserves power for itself | A 65W charger goes in, the laptop reports something in the 40s or 50s. | Read the hub's listed passthrough figure, not the charger's rating. Hubs state something like “100W in, 87W out”; the gap is what runs the hub and its ports. Buy a charger sized above your laptop's need by that gap. |
| The cable is capped at 60W | Charging is fine at the wall but slow through the hub, and the cable came in the box with something else. | A plain USB-C cable carries 3A (60W). Anything above that needs a 5A e-marked cable, and 240W needs a cable rated for it. Cable length does not change the ceiling, but a thin no-name cable often will not hold the rated current. |
| Attached devices are drawing from the same budget | Charging slows further the moment a display, SSD or phone is plugged into the hub. | Everything on the hub is paid for out of the same input. A bus-powered SSD and a 4K display can take a meaningful slice. Move heavy draws to their own power, or accept the slower charge while docked. |
| The charger and laptop never agreed on a high profile | The laptop warns about a “slow charger” or charges only while asleep. | USB-PD negotiates fixed profiles (5V, 9V, 15V, 20V…). If the charger has no 20V profile at enough current, a high-wattage laptop falls back to a trickle. Check that the charger lists a 20V output at the amperage your laptop needs. |
| The port is a downstream one | It charges properly in one port of the hub and slowly in another. | Only the hub's upstream/PD-in port passes wall power to the laptop. The other USB-C ports are for devices, and often cap far lower. The listing names which port is which. |
An inline USB-C power meter turns this from inference into a reading, but the sequence above is enough to tell a cable problem from a budget problem.