XPS

[jovaseq]

Hi, I have bought the new XPS 13 9300 and I wanted to connect it to my ultrawide monitor. I have tried 3 different ways: usb-c, thunderbolt (my monitor has a tb3 input) and through a TB dock. In all 3 ways the laptop would start and stop charging frequently and also disconnect from the external monitor. What I noticed is that this problem would go away as soon as I plug in the charger. Which shouldn't be the case as my monitor as well as the dock provide 85w. What could be the problem? I am going crazy as this was the reason to buy the XPS 

[Tesla1856]

And how is that a problem when the large monitor is restricted to the desk-use-only anyway?

Sounds like the little XPS-13 just wants some power.

What is make/model of Dock?

And please, one post per issue please. Let's use your thread here.

[jovaseq]

The dock is the Caldigit TS3 plus. However, the laptop should be able to charge and display on an external TB3 monitor with only one cable, or?

[Tesla1856]

OK, well the Caldigit TS3 Plus is pretty nice, and you should see some good compatibility. However, it sounds like it is working to your satisfaction, except for the power-handling.

Are both the Caldigit-TS3-Plus and XPS-13 (9300) both running the latest firmware ? 

[jovaseq]

Yes, but I don't want to have 2 cables on my laptop since one should be enough.

Firmwares are up to date.

[Tesla1856]

How about the firmware on the LG34wk95u ? (since it sounds like it is also connected in every system-connection scenario) 

[jovaseq]

I have done this as well. Generally I am an Update-Freak.

I think the problem is the XPS. and it's a shame because this thing costs 2000€

[Tesla1856]

I don't want to have 2 cables on my laptop since one should be enough.

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Well, I have both the MacBookPro-15 (2018) and the new XPS-13 (9300) here. However, I have no high-end docks here at the moment (only a little hub, with no power-delivery).

Typically, you can't connect power-rails together. I'm not sure on USB-C/TB-3, but I would imagine that the connected devices negotiate, and the one they decide is most powerful ... supplies the power. What do you think?

Edit: I later found this. Looks like I might have guessed correctly, after all:

https://forums.macrumors.com/threads/connecting-tb3-to-multiple-power-sources.2128888/

[jovaseq]

I don't understand what you mean exactly. One purpuse of a dock is to supply power. However there seems to be a problem with the port of the laptop as it does "accept" the power from the dock.

[Tesla1856]

So, if you power-up the Caldigit-TS3-Plus Dock, and then connect only the XPS-13 (9300) to it 
(no LG monitor or anything else connected) ...

... you are saying the dock will not power and/or charge the XPS-13 ?