Off Topic - USB-A to USB-C

[davehorne]

I bought a device that came with a USB-A to USB-C cable.  I initially connected that device to a USB-C to USB-C assuming it would charge, since I naturally assumed the wall wart was essentially a passive device; if the connected device asked for 20 watts, it would receive 20 watts,  if the connected device only asked 5 watts, it would only receive 5 watts.

Is my thinking correct?
 
The issue, the device would only charge using the USB-A to USC-C cable.  

My question, why?

[UNKNOWNUSERNAME]

i thought all samsung devices are now sold with USB-C - USB-C. Where did you purchase this device from?

[UNKNOWNUSERNAME]

My theory was right, im just confuzzled as to why yours came with USB-A to USB-C🤔🤔

[davehorne]

First, the device in question is neither from Samsung nor a phone, my question was simply, why would a USB-A to USB-C work, but not a USB-C to USB-C? 

[UNKNOWNUSERNAME]

Sorry i just assumed you purchased a samsung device since posting in a samsung forum.

[GoanGeek]

I hope this helps.

https://www.maplin.co.uk/blogs/expert-advice/usb-a-vs-usb-c-differences-benefits-and-more

[davehorne]

It was nice of you to provide that link, but to be honest, nothing in that article explained specifically why the device in question, a USB-C device, could only be charged by using a USB-A at the other end of the cable. 

[Reylob]

Hi @davehorne 

It has to do with the adapter-device charging protocol, or the cable. Your device is not able to negotiate the power requirements with your adapter.

The cable might be wired differently. Have you tried reversing the USB C cable? It should work both ways but only if the manufacture followed the specs. I have devices with the same issue.

Most modern devices are able to negotiate the right amount of power and they you will behave as you described.

[davehorne]

I did try reversing the USB-C to USB-C but that made no difference.  The device only charges with the USB-A at the wall. 

[UNKNOWNUSERNAME]

Following, You have your post in the S24 thread, And did *NOT* specify that this was not about a device other than samsung. Sorry for my confusion in this matter.