I have a mount for my iPad mini that came with a specifically shaped USB-C to A cable. I want to shorten it and have the new end be USB-C as well.
I was hoping I could just cut the end of another USB-C cable off and join the two together, but that’s not working, I get no power at all…I’m sure it has something to do with the power negotiation USB-C uses. Just hoping I can figure this out.
Any thoughts?

 

A USB C PD charger will output 5 volts with no negotiation. At best, you probably have wires mixed up – USB C uses two conductors for V+ and two for ground, allowing the connector to work no matter the orientation. Worst case, you have the polarity reversed and you've released the magic smoke from the iPad mini and/or the charger.

Don't trust the colors of the wires in the USB cables – verify everything.

 

Certainl JC is correct about not trusting wire colors. And while for DC charging an average splice can work, for that high speed communication it will probably not work.

 

Just buy the right cable.

 

Just buy the right cable.

Quite probably the "right cable" is not available at any price, in a reasonable time, and of a decent quality.

 

USB-C is a standard. I find USB-C to USB-C in all different lengths on Amazon.

 

USB-C is a standard. I find USB-C to USB-C in all different lengths on Amazon.

I do not trust Amazon any farther than I could throw it. too many items my wife has bought wind up not being close to the description or the picture. So I do not consider it to be a trust worthy source of anything. And perhaps if one only wants the common variation of a product, a selection from standard configurations will be OK.
The TS mentions a non-standard shape and a non-standard length. Those will not be found in a list of standard configurations.

The ability to shape available materials into the form one chooses to have is a great freedom, while the lack of such ability is certainly a lack of freedom.