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I don't know too much about USB-PD. I understood that USB-PD requires negotiation between the charger and the receiver. So probably my Windows laptop (Dell XPS 9570) should be able to know the current wattage input it's receiving. Windows probably also know since it's popping up saying slow charging. So I'm curious to know what wattage is my Dell is getting and is it getting the 100w it supposed to get?

My setup is a Dell XPS 9570 connected to Razer Core X Chroma eGPU. I've tried two cables, the Thunderbolt that came with the Razer Core X and the Apple Thunderbolt 3 0.8m, both of them still give that slow charging pop up.

Cheers!

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  • $\begingroup$ Do you expect the system to be able to tell you? Or why not make an adapter so you can measure current & voltage direct, then calculate power. or you could use one of those plug-in power meters at the mains plug... $\endgroup$ – Solar Mike Aug 10 '19 at 6:44
  • $\begingroup$ Since Windows is able to show the message that the machine is charged slowly, so I felt like it should have some sense of power input. I didn't want to use the plug-in power meter since it's a eGPU box so some of the power are being use to power the eGPU too. $\endgroup$ – sasawatc Aug 11 '19 at 4:28
  • $\begingroup$ @sasawatc, When it is stating slow charging, is battery on the laptop fully drained or 90% full. $\endgroup$ – Mahendra Gunawardena Aug 11 '19 at 4:48
  • $\begingroup$ @MahendraGunawardena both when partially and full. I actually never tested it when I'm in low battery. Are you trying to suggest that the power supply is being lowered as the battery approach to full-charge? $\endgroup$ – sasawatc Aug 11 '19 at 20:21
  • $\begingroup$ @sasawatc One more thing, does your USB-PD cable support Alternative mode. $\endgroup$ – Mahendra Gunawardena Aug 12 '19 at 2:23
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Based on the information provided your Dell XPS 9570 might not be designed fully utilize the USB-PD standard. The wattage of the power adapter with the circular jack will provide a good clue as to the maximum charging power. A brief review of Dell XPS 9570 technical specification I was not able to determine maximum power capability of your laptop. Also there is also evidence based on some of references below that your laptop model is USB-C complaint.

With regard to USB-PD standard, maximum current supported is 3 or 5 amperes. The current supplied is determine by the eMarker chip that is embedded in the USB-PD cable,

enter image description here

If the Dell XPS 9570 is capable of supporting USB-PD maximum current capabilities then the USB-PD cables might not be able to support the maximum current capabilities. This can be identified by looking the cable specifications or using a e-Marker reader like the one below.

E-marker reader

The system including the cable in this scenario support 20V and 5A. If interested I have provided a few references to help further investigate.


References:

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