pi5 psu?

The psu is not one expressly declared for use with the Pi5, or is it? Afaik the Pi5 needs 5A plus the USB Power Delivery feature, which the Pi4 psu does not have. The Pi4 psu won't let you run the Pi5 reliably. So you probably need another psu after all, I'd recommend the official one, you can never go wrong with that.

-jw-

But it is the official one. Or at least, was bought as such and is so labelled. A huge wall-wart.

Bought from pi hut back in February; carries authentic-looking labelling.

There is an official one guaranteed to work with the Pi4 only and a different official one for the Pi5, and only this one has the PD feature. Check what exactly you have bought. If this really is the Pi5 version, it is defective and you should consider returning it.

-jw-

Are you using something like the Argon ONE V3 case? That needs the config.txt line "usb_max_current_enable=1" as it filters the power through its hardware. Bloody pain!

Does the PSU have a captive cable, or is the cable removable? Are you perhaps using a substandard cable?

Where did you buy the PSU?

Theo

That doesn't sound right.

Raspberry Pi sell three different USB-C PSUs:

- A 15W PSU for use with the Pi 4/400 only.

- A 27W PSU for use with the Pi5/500 (and 4/400)

- A 45W PSU which is like the 27W but more powerful and can power some laptops, etc.

The 27W and 45W PSUs support the USB Power Delivery spec and will provide a range of powers/voltages after negotiation with the device. The 15W PSU provides only 5V/3A, and is stated to be inadequate for the Pi5 and later.

There is no official "kosher" 25W PSU from Raspberry Pi.

I think the 27W PSU was the original official version.

Also, it is worth making clear the rPi5 USB PD is unusual, it only uses

Whereas my normal USB PD plugs produce their specified high wattage by boosting voltage, so they don't work with the rpi5 at all. Which irritated me a lot when I found out.

ISTR it can give other voltages, but the Pi5 will only negotiate 5V - or

From the spec: The available profiles are 9V, 3A; 12V, 2.25A; and 15V,

I think its 5.5V at 5A.

(OP) That seems to be what I pi-hut delivered. So why the pi5 is moaning, I can't think. 5.1V/5A, 9V/3A, 12V/2.25A, 15V/1.5A printed o0n it.

(I've moved back to a pi4 for the moment: there seems a problem in the latest rasp OS on the pi5 that stops perl/Tk working correctly. Needs checking out.)

Yes, that's right, my statement was muddled.

And 3A * 9v =27w, even if the rPi5 can't use it.

Hopefully the next round of Pi type devices will use more standard, higher voltage, USB PD. If my cheap USB plugs can do PD it shouldn't be too expensive to support?