If I connect my USB PD power bank to my Android phone (which also supports USB PD) I am given the option to charge the power bank from my phone or vice versa. This is, of course, one of the standout features of USB PD, and from what I understand a compulsory one too.

However if I connect the very same power bank to my laptop (a HP Envy 13 that also supports USB PD) I am only able to charge my laptop from the power bank, with seemingly no way of changing the direction of charging.

I usually charge my laptop with a 65W mains charger at home and then take my power bank with me when I leave (the laptop also has a proprietary charging port), so it would be nice to be able to charge my power bank from my laptop so that it's ready when I next need it.

How can I force my laptop to charge my power bank?

  • There are 16 different models of Envy 13's, which do you have?
    – Moab
    Oct 6, 2019 at 18:33
  • @Moab My laptop is the Envy 13-ah0001na, but given that I have said it supports USB-PD 2 I don't see why the exact model is relevant Oct 7, 2019 at 12:13
  • So we can do some research to possibly answer your question.
    – Moab
    Oct 7, 2019 at 13:52
  • Two way USB-PD is not enabled in that model laptop, You mostly see that in Smart Phones. It will charge devices connected to the laptop which is one way.
    – Moab
    Oct 7, 2019 at 14:15
  • @Moab Sorry, I didn't mean for that to come off like that, I was only explaining why I didn't initially mention that in my question. Why do you say two way PD is not enabled though? I often use my laptop to quick charge my phone (the phone says charging rapidly, and charges as quickly as it would with a USB-PD charger), and from what I understand two-way power is part of the PD 2 spec anyway? Oct 8, 2019 at 21:22

1 Answer 1


When plugging two USB-C devices that support both sinking and sourcing power together they will pick a role at random. Perhaps some devices will prefer to source than sink, or vice versa, so maybe it isn't so random. There's a short memory on these to allow swapping roles by unplugging and reconnecting. This gives the impression to some people that a USB-C to USB-C cable has a preferred direction of power flow and by flipping the cable they are redirecting the flow. That is not the case, assuming the cable is built to spec, the disconnect and reconnect cycle is what is reversing the flow.

While a laptop can sink something like 100 watts of power they can typically source only 7.5 or 15 watts, that would be 5 volts at 1.5 or 3 amps. If your power bank is capable of charging from 5 volts then you should be able to charge it from your laptop, but it might not be as fast as you like.

One way to force the direction of power from USB-C to USB-C is with the use of a USB-C/male to USB-A/male cable and a USB-C/male to USB-A/female adapter. With the USB-A connection in the middle power can only flow from the device at the adapter end into the device at the cable end. The power flow will be limited to that allowed by the USB-A port but the laptop will likely have the same power limit out from the USB-C port. This might be helpful because some people find that with a USB-C to USB-C cable a power bank will charge from the laptop, reset the connection, and then discharge into the laptop. That means finding a dead power bank in the morning.

I've found that laptops will often choose to draw power from whichever attached power supply reports being able to supply the most power. If your laptop power supply is rated for 65 watts and the power bank is rated for 80 watts then the laptop might prefer to draw power from the power bank if using a USB-C to USB-C cable. Putting a USB-A adapter in the USB-C port on the laptop, then connecting the power bank to the adapter by a USB-A to USB-C cable (male on both ends) then power can only flow out of the laptop into the power bank.

This means carrying some extra cables but it adds some convenience in not having to "babysit" your power bank as much. Use a USB-C to USB-C cable to connect the laptop to the power bank when you want power from the power bank to the laptop. When you want power from the laptop to the power bank then use the USB-A/female adapter on the laptop and the USB-A/male cable on the power bank to connect them.

It's quite possible that the power bank will refuse to charge from the laptop because it is supplying only 5 volts and it wants to see 9, 15, or 20 volts. I have not seen any laptop that will supply more than 5 volts from it's USB-C ports so it is unlikely your laptop is any different.

There may be other solutions to your problem but to offer them I'd like to know more about the power bank so I'm not speculating too much.

  • Fun fact: If you charge your laptop from a powerbank and end up depleting it, the flow will reverse without warning. Watch out!
    – Qwerty
    Jun 16 at 16:03

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