Can I draw power from the USB-C port on the XIAO? make it a battery pack

I created a devise, and I also want it to be a 5v power pack…
The XIAO is powered via de 5v pin, a buck converter (2amp max) is used to regulate from 12v to 5v.
A charge balance board is used to handle the 3x18650 cells, outputting 12v.

So I tried connecting:

  1. Another XIAO: It successfully powers On the connected XIAO! it blinks…
  2. a Pixel 2XL smartphone (with 30w fast charge): it shows that it is charging for 1 sec. Then it stops charging it. I think is has to do something with the power drawn.

Any idea about what is happening? and is there a workaround? Do I have to enable something?

Your phone probably wants to charge at a higher voltage. USB-C can go up to 20V (?).

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My Pixel 2XL supports Power Delivery… so you are right, it will try to up the voltage to 20v.
But I think that it should ask for it first, before it just draws it… right?
It should select from what the XIAO can deliver, and if it can’t deliver more than 5v, then why force it into shutdown mode?? it seems something related to the USB-C on the XIAO.

The ability to draw 5v and turn the XIAO into a low power battery pack is appealing to me.

Is there something that could be done?

Power Delivery explained.

Another thing I just noticed…
If, I connect my Pixel 2XL to the XIAO, and I don’t supply 5v to the pins on the XIAO…
then, my phone powers the XIAO.

It is clear that the phone and the XIAO are resolving their power differences the best they can.
But Power Delivery is somehow forcing the XIAO to stop supplying.

Is this a Hardware problem or a Software?