MacBreaker's post in Power bank or ups for Orange pi pc was marked as the answer
There a differed ways to connect.
You have skills with soldering or not?
Ok,easyst way is to buy a usb to DC 4mm connector cable and a power source form Raspberry Pi.
It doesn't matter if mirousb or usb-c connector.
Plug all together and your done.
Bevor i forget, i use 3000 miliampere Cells.
Made sukcessfull tests with 1 hour disconnect from mains and reconnect.
All wthout problems...