HACKER Q&A
📣 kuon

How to navigate USB-C charging hell


I realize this topic has been discussed numerous times, but after some research I found about 50 different "theories" on how it is supposed to work.

As a developer and electronic engineer, it deeply frustrate me to have no good understanding of it. I am quite sure that the actual protocol and electrical details are simple, but because everybody comes with their own theory, navigating google results is really hard.

Long story short, I built a new threadripper workstation, and none of the gazillion of USB port will charge my One Plus 5T phone.

I tried all the the A-C ports with different cables (aren't A port just 4 contacts? what can be in the cable, resistors?...). I also tried C-C and it doesn't charge either.

So, two questions:

- Is there a good, technically precise and right explanation of the whole situation? I tried reading the USB standard, but it would take days to extract a proper understanding of it.

- In there an adapter or something I can use on USB-C port of my workstation to provide a "charge port" for my phone which seems to require some voodoo magic to charge?

I am posting on HN because it has a lot of visibility, and I hope this post might become a beacon of hope in the USB situation (this part is very pretentious, but HN did surprise me quite many times).


  👤 wmf Accepted Answer ✓
There's classic USB (5V @ 0.5A) which is supported by every USB port and USB Power Delivery (USB-PD) which can negotiate power up to 240W. Your phone may require PD to charge but none of the ports on your PC provide PD thus it doesn't charge. USB-PD used to be really expensive and now it's still expensive so maybe only Apple supports outgoing PD from their computers.

Then there's proprietary charging protocols like Qualcomm Quick Charge that I hope are being phased out.


👤 GekkePrutser
It will never fast charge on a OP5T but it should slow charge just fine. Only later OP phones (8 onwards) will medium fast charge on standard USB-PD (15 or 18W not the full 35 or 65W). Eg a laptop charger or Qualcomm QC 3.0 or higher.

But slow charging should work on pretty much anything. Having said that, USB-C has a protocol for active devices connected to each other that agrees which device will deliver power to which. Previous USB standards didn't need that as the cable has different ends and this would determine this based on the port type. USB OTG however started to break this assumption based on plug type but needed a wiring change.

So they made it fully dynamic in USB-C but only if active devices are on both ends. Then they'll negotiate. If an active device just sees 5V from a dumb power supply without any kind of signalling it should always slow charge only. It will assume a dumb USB1 power supply meaning 5V at 500mA so 2.5W charging.

Perhaps this needs some configuration in your case though I've seen every computer charging my oneplus just fine. Try to select USB charging only mode in your oneplus.

A USB condom should also work, it's a cable that only permits the 5V through and nothing else. It's used to avoid public chargers from trying to access your files in secret.

As for technical write-ups hackaday has done some in the past but they're a news site so it's not too easy to find back.


👤 simplyinfinity
Ah.. OnePlus is a special kind of brand pulling an Apple move when it comes to charging. Only their chargers will do fast charging. Nothing else. I've got an anker charger that supports 60w PD and QC, other brands of phones and devices quick charge no problem, but not my two OnePlus devices - 5 & 9 PRO

P.s over the years I have tested a handful of portable batteries and chargers from other vendors. Nothing seems to work.


👤 tiernano
Would using one of those little USB charge monitors (like this one: https://amzn.to/310fIou) help? it should show you what the charge is coming in and out of the mobo and different ports... I have used one to test cables, etc... I think thats the one i actually have...

👤 mardiyah
Must read the V and I output at end by use a MM

Then side it by side with the rating data of the wanted charged device (on its manual)

basically to work the charger rating must be greater than the device's


👤 DesktopECHO
> Long story short, I built a new threadripper workstation, and none of the gazillion of USB port will charge my One Plus 5T phone.

Sounds to me like your PC is busted.


👤 ggm
the key points being good, and technically precise.