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I have a USB-C charger with Power Delivery specification (it can charge 5/9/12/15V==3A and 20V==4.35A). Not sure if this is Power Delivery 2.0 or 3.0. I'm using a USB-IF Certified cable, up to 100W (of course, with an e-marker chip). If I connect this charger to my projector, it charges up to projector charging capability which is 40W (20V==2A).

However, when I connect it to my non-Power Delivery phone (USB-C input), it does not charge at all. The phone charges when connected to a regular USB-A charger (using a USB-A to USB-C cable).

From my understanding, a USB-C Power Delivery chargers and cables are still supposed to work with 5V (regular USB voltage) and up to 3A. So, the phone should receive charge.

Any idea why the phone is not charging when using this USB-C Power Delivery charger and USB-IF certified 100W cable? Maybe the e-marker is preventing any power to be delivered because the phone doesn't support Power Delivery? I thought that in this case it would simply deliver 5V and whatever amperage is being pulled.

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  • Some devices, e.g. Apple's, have specific requirements for charger ports, such as a certain value resistor to identify it as OEM (or at least compatible). See epanorama.net/blog/2010/08/18/apple-charger-secrets
    – DrMoishe Pippik
    Commented Feb 14, 2020 at 3:44
  • @DrMoishePippik This phone charges with any other USB-A charger and cable. My main question is if the use of a Power Delivery charger and/or USB-C 100W (e-marker) cable is preventing it from charging. I would like to understand why. I was not expecting no charge at all (not even slow charging is happening).
    – igorjrr
    Commented Feb 14, 2020 at 15:58
  • Likely the Power Delivery protocol has a similar termination requirement... else how would it determine whether to deliver 5 V or 15 V.
    – DrMoishe Pippik
    Commented Feb 14, 2020 at 18:16
  • No, AFAIK a USB-PD device will only provide power if the USB-PD-power-negotiation has been completed (which requires a USB-PD device on each side of the cable). Because otherwise two power sources may be connected on each side of the cable which would of course cause a shortage if both would just supply power.
    – Robert
    Commented Feb 14, 2020 at 18:53
  • @Robert thanks, but it seems to me that in the case negotiation fails, PD port will supply the standard 5V up to 3A, like a regular USB-A port would do. This is not happening, no charge at all is supplied. Who to blame the lack of power? The PD USB-C port, or the e-marker chip inside the USB-C 100W cable?
    – igorjrr
    Commented Feb 14, 2020 at 19:51

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