Hi all;
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.
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.
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.
Mike Scott wrote:
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.
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-
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.
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.
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-
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.
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.
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.
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/
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.
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
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/
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