Subj : Re: pi5 psu?
To   : All
From : Mike Scott
Date : Mon Oct 13 2025 19:44:16

On 13/10/2025 18:35, Chris Townley wrote:
> On 13/10/2025 18:32, Chris Townley wrote:
>> On 13/10/2025 18:20, Pancho wrote:
>>> On 10/12/25 16:03, Daniel James wrote:
>>>> On 09/10/2025 16:42, Mike Scott wrote:
>>>>> I've just installed rasp OS on a new pi5 for the first time. It 
>>>>> moans the psu is insufficient, and can't deliver 5A. But the psu 
>>>>> itself - a kosher raspberry pi one - claims it will deliver 5A/25W.
>>>>
>>>> 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 5V and negotiates current up to 5A (which somehow = 27W).
>>>
>>>
>>> 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 5.1V I believe
> 
>  From the spec: The available profiles are 9V, 3A; 12V, 2.25A; and 15V, 
> 1.8A, all limited to a maximum of 27W
> See https://www.raspberrypi.com/products/27w-power-supply/
> 
> 

(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.)




-- 
Mike Scott
Harlow, England

--- PyGate Linux v1.0
 * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

.