Hi Bob,
Thanks for posting your question here! USB laptop docking stations like Plugable UD-3900 can’t charge laptops, so you’ll definitely still need that laptop’s power supply whenever you dock and want to charge at the same time. Sorry about that!
If you are interested, here is some background on why:
Every laptop can have a different type of physical power connector and adapter specs - so there isn’t a way to create a completely universal charger. And for a USB connection, power for charging goes from your laptop to the USB devices you connect, but not in the other direction. So any power heading back to the laptop would have to be on its own special cable.
Hope the above information helps! If you need any additional information, please do feel free to shoot us an email at support@plugable.com. We are here to help!
Regards,
Roze