How can I make a 'PD' battery port pass 9v instead of standard 5v?
The name for these add on modules to enable USB Power Delivery or Quick Charge voltages are called trigger modules. &quot;Trigger&quot; is the keyword.
If you want to design your own then you can use an usb power negotiation IC like TIs TPS25741A or NXPs PTN5100 or any number. Googling &quot;usb power ic&quot; should show a ton. Make sure you include what type of protocol you need like PD or QC and maybe version. They are not intercompatible but many changers may support both. My usb power bank supports QC 2.0 but not 3.0, and not PD.