Don't get that, sorry!I haven't checked what the power supply will do without the resistors. Possibly nothing.Since my Type-C socket only has power and ground wires, do I need to add a 5.1kΩ resistor for the official Raspberry Pi 5 power supply to work safely?
With the resistors (there should be one from CC1 to GND and one from CC2 to GND), it should supply 5V 3A. It should only negotiate 5.1V 5A when connected to a compatible USB PD Sink (like the Pi 5).
There are a number of cheap USB C PD "decoy" boards that can negotiate various voltages, but they are all the old standard ones, so 5V 3A at best.
You could use one of those to negotiate a higher voltage (12V, 15V or 20V) to power your UPS.
Does your step-down converter support the correct PD signalling to tell the Pi it can provide 5V 5A? If not, the Pi will assume 5V 3A unless you override that in the Pi configuration.
Why would a PSU need to have any resistor on CC1/CC2?
When you have 2 wires only make sure to supply 5V (!) to your Pi and it will be happy. Supplying higher voltages will kill it.
Some 'evidence pictures (posted long ago already)
The cable in use is a 2-wire USB-C cable, nothing is on CCx
Statistics: Posted by aBUGSworstnightmare — Wed Jul 16, 2025 10:51 am