Thinkpads Forum

I wanted to try out connecting a T25 to the Lenovo Thunderbolt Workstation Dock, and everything works great except that the laptop won't charge via the Thunderbolt 3 port.



I have the laptop's Thunderbolt 3 port connected to the Thunderbolt 3 port on the back of the docking station, but the laptop isn't attempting to charge. There isn't even a warning about there not being enough power to charge it via the Thunderbolt 3 port.



Also connected to the dock are 2 DP monitors, a wireless mouse receiver, a USB wired keyboard, and an Ethernet cable. These devices all work as expected. Both the 230W and 65W power supplies are also connected to the dock.



I have installed all available updates from Lenovo Update, as well as the TB3 firmware update posted here: https://pcsupport.lenovo.com/jp/en/prod ... /thinkpad-...



Does anyone have any suggestions on what I might try to get charging to work, aside from just connecting a power supply to the laptop directly.



TIA!

These types of docks do not offer charging through the input port. Think of it this way - you can't charge a computer using a powered USB hub or dock over the USB port!

The Thunderbolt port can only charge the ThinkPad using the dedicated USB-C type chargers. The Thunderbolt (and USB) docks do not charge the computer over the data connection port.

If you need a dock to charge while offering port expansion, you will need something that connects to the docking port on the bottom of the machine, like this: https://www.lenovo.com/us/en/accessorie ... 40A20090US

That's not true; USB-C and Thunderbolt can be used for charging. This works for me with the TP25 and the X1 Carbon through the USB-C dock or the Thunderbolt 3 Dock.

In this case, I suspect that they rigged the workstation dock so that charging via the Thunderbolt port can only work if you use their special cable that also connects the rectangular charging port. Probably this is why this dock only mentions compatibility with certain workstations. This is just a guess, though.

dr_st wrote: ↑

Sat Feb 23, 2019 2:22 pm

That's not true; USB-C and Thunderbolt can be used for charging. This works for me with the TP25 and the X1 Carbon through the USB-C dock or the Thunderbolt 3 Dock.

In this case, I suspect that they rigged the workstation dock so that charging via the Thunderbolt port can only work if you use their special cable that also connects the rectangular charging port. Probably this is why this dock only mentions compatibility with certain workstations. This is just a guess, though.

This seems likely. The workstation dock's combined Thunderbolt 3/slim power connector special cable is only useful for those laptops that have the Thunderbolt 3/slim power connector directly adjacent to one another so that the cable can connect to them both simultaneously. In doing so it provides power over the slim power connector and data over the Thunderbolt 3 connector, presumably. So the dock probably doesn't care to provide power on the Thunderbolt 3 port. Perhaps this is to avoid the workstation laptop trying to draw power on both the TB3 and slim power connector at the same time. The workstation laptops may need to draw more than the 100W that the TB3 cable can provide, necessitating the extra connection to the slim power connector.

Still, it would have been nice if they found a way to allow the TB3 port to provide power if the slim power connector is not in use. Though they provide the Thunderbolt 3 Gen 2 Dock (non workstation) for this functionality.

Interesting, I stand rightly corrected. Now that you bring it up I have also seen some models with a small rubber plug that goes over a connection that's adjacent to the power plug, which I read somewhere was a dock connector.

bra1niac wrote: ↑

Sat Feb 23, 2019 5:00 pm

Still, it would have been nice if they found a way to allow the TB3 port to provide power if the slim power connector is not in use. Though they provide the Thunderbolt 3 Gen 2 Dock (non workstation) for this functionality.

Lenovo has a shameful history of deliberately locking out features/compatibility of docks to force people to buy different docks for different products. Usually it was via mechanical blocks, which are rather trivial to defeat; this here may be something else, but I hope some enthusiasts can figure out how to beat the protection.

theterminator93 wrote: ↑

Sun Feb 24, 2019 1:04 am

Interesting, I stand rightly corrected. Now that you bring it up I have also seen some models with a small rubber plug that goes over a connection that's adjacent to the power plug, which I read somewhere was a dock connector.

Yes, that's the new sideways mechanical dock plug used on *80 series, the new X1 Carbon, and some other new models.
https://i.redd.it/6bxexq4827001.jpg

I like it less, but have to admit that there are advantage to this system - it allows ultra-slim models to use mechanical docks as well.