Usb c dac not work with battery pack supply?

[shoto]

I modified a usb c to cable to add external 5v battery pack input to be able extend the phone battery when devices are connected.

For BHD pro DAC this cable works with my pc but when I try with my phone it does not work.

BHD had red light in 'connected' state but it wont go into the 'playing' state.

I reconnected 5v line to the cable and it works again, so cable is not damaged, phone doesnt like the external supply

Anyone know why this is? Some kind of smart 'fault' sensing feature of usb c or android?

 

[Jimbob54]

Some Android phones /builds won't accept power in and audio out together.

 

[shoto]

The power line from phone is left unconnected. only the usb device gets power from pack.

 

[Mikig]

I bought a similar cable online with two "y" heads. In my case it doesn't work with PC but it works with smartphone. I use it to power SMSL PO100PRO.

 

[shoto]

I tested on different pc with both usb and usbc port. Again usb works while usb c doesnt, so its usb c related problem and not a device specfic one.