01-09-2018 01:57 AM
My 720S is connected to a ThinkPad USB-C docking station. The manual says:
When I connect the docking to Port 1 the ideapad gets power (it's charging) but the display connected to the docking does not work.
When I connect it to Port 4, the second screen on the docking works fine, but the ideapad doesn't get PD (Power delivery).
Does this Port4 support this function? What are the select models?
Thanks in andvance for your help.
04-23-2018 06:20 AM
I have the same problem, but not with a docking station...
I bought the "Lenovo ThinkVision P27h-10, 27" (61AFGAT1)" TFT Monitor with USB-C and USB Power delivery.
If I connect the monitor to one port of the Lenovo 720s, I get power. If I connect it to the other port, I get USB and Displayport, but no power.
This is very frustrating! I thought the USB-C cable was supposed to eliminate the need for a docking station and allow charging + displayout over one cable? Who is at fault here? I've tried this both with a 720s with Core i5-7xxxx as well was with the Core i5-8xxxx Quad Core CPU. (we have multiple 720s here).
04-23-2018 03:47 PM
Just thought I'd chip in - not sure whether I'm of any help. I also own an Ideapad 720s-13IKB.. I was quite surprised also to learn that the designated charging port was in fact _not_ the one supporting display connection.
In my case, though, the display connection port _does_ support charging (and, interestingly, does charge my laptop faster than the charging port).
That goes to show that in both your cases, something else must be at play. Have you tried to charge your device directly (via the display port USB-C port)? (That is to say, without the dock/display in between. I tried to charge my laptop with a docking station before, and while it did work, the charging was really really slow.
I suspect this (and your issues, too) might have to do with the amount of power supplied: The original charger that came with my laptop is a 45W charger - since both display and docking station require some power to themselves (USB power delivery on other ports, operating power for the display), there just might not be enough left to properly charge the laptop.
I just now ordered an original Lenovo 65W charger to test my hypothesis - I'll check back and report my results!
In the meantime, I'm curious as to whether any official Lenovo support staff respond to this thread.
04-25-2018 08:56 AM
Same problem here with an Ideapad 720s 13IKB. Via port 1 it charges, but the external display gets no signal (plus Windows shows an error message concerning displayport). Via port 4 it does not charge (neither with nor without a hub inbetween), but the external display does get signal. I have tried this with both an Aukey and a Lenovo USB-C Hub. I hope we get an official answer, because this implementation of USB-C just seems absurd to me.
05-21-2018 07:09 AM
Interesting - with my 720S-13IKB I am using a thunderbolt dock. I works fine and charges the laptop when connected to port 4 (the Thunderbold port), with 2 displays, printer etc.
The dock does nothing if connected to port 1 (doesn't even charge), but the supplied USB-C charger works only in port 1.
So this configuration seems to be working for me with this high end dock. I did have to instal the TB software update and firmware for the dock.
I agree it's confusing. You would think it would charge over either port with any attached device supporting power delivery, and especially a monitor designed for this application with a built in dock.
06-10-2018 07:44 AM
The one I'm using is called Thunderbolt 3 Dock (40AC)
It's not the Thunderbolt Graphics Dock, because I only use it for office work.
Note - it only charges the laptop if the higher capacity AC adapter that comes with the dock is powering the dock. It needs the extra wattage for everything it does.
After all firmware and BIOS updates, it works very good. It comes with a short USB-C cable for a reason (check google). I bought longer cables that work but they are the expensive "active" type.
07-03-2018 06:59 PM - edited 07-03-2018 06:59 PM
I have now tried the Ideapad 720s (Quad Core 8xxx CPU version) with a Lenovo P27h-10 display which was produced more recently (late April 2018 instead of late November 2017) and the result is the same. The Lenovo 720s Laptop won't charge on one of its two USB-C ports and it will charge but not display a picture on the other USB-C port.
But the P27h-10 monitor works perfectly fine with a newly purchased Dell 5290 2-in-1 Tablet with USB-C Port. Here the full Docking functionality is present, only 1 cable for Power, USB and Display connectivity. Just like it should be!
And the strange thing: The Ideapad 720s seemed to mostly work with a USB-C Monitor from HP (HP EliteDisplay E273m). It was even charging I think, but unfortunately this HP monitor can supply only 15W and that was not enough to keep the battery at 100%. And it often took a few tries until the connection was properly established - so not a perfectly reliable combo.
So USB-C works better if you are not stupid enough to combine a Lenovo Laptop with a Lenovo Display. Perhaps the 720s would even work properly with a more expensive USB-C Display? Both the HP and the Lenovo I've tried are in the 300-350€ price range, I'm not willing to spend 600-1000€ for a EIZO display...