Smalltimer
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Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 2:04 pm

I purchased a Pi 4B board along with the 3A type-C rated power supply - or so I thought.
Only to find that the vendor shipped a 2.5A micro-usb power supply with an adapter instead.

The board on the other hand is completely unstable - locking up, none booting between restarts etc.
I contacted the vendor, and was told that 2.5A is enough, but I keep reading that 3A is a must with these boards.

Is the vendor right, is the documentation wrong?

trejan
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 2:21 pm

No. You need 3A if you want to fully utilise the Pi 4. The official PSU is recommended as it has been tested to be compatible and able of supplying 3A.

From the Pi 4B specifications:
A good quality 2.5A power supply can be used if downstream USB peripherals consume less than 500mA in total.

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rpdom
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 2:34 pm

3A is recommended if you are going to fully load the USBs with the max 1200mA, but 2.5A is fine. A lot of people, including me, are running the Pi4B using a Pi 3 PSU with USB-C adaptor.

If you weren't going to use the USB ports at all, you could get away with a 1.8A adaptor.

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B.Goode
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 2:46 pm

Smalltimer wrote:
Wed Aug 28, 2019 2:04 pm
I purchased a Pi 4B board along with the 3A type-C rated power supply - or so I thought.
Only to find that the vendor shipped a 2.5A micro-usb power supply with an adapter instead.

The board on the other hand is completely unstable - locking up, none booting between restarts etc.
I contacted the vendor, and was told that 2.5A is enough, but I keep reading that 3A is a must with these boards.

Is the vendor right, is the documentation wrong?


Until proven otherwise in a particular situation, I would tend to believe the statement made by Raspberry Pi themselves in respect of their own product rather than the word of a vendor whom you seem to allege has substituted alternative goods for what you thought you ordered. (But the actual wording of your order, and thus the agreement between you, would be of interest here... )


Also, I notice you say " the vendor shipped a 2.5A micro-usb power supply ". Just "a power supply"? Not necessarily an official Raspberry Pi spec Power Supply? The latter, with an adapter, is an option mentioned by Raspberry Pi, as cited.

Smalltimer
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 3:51 pm

B.Goode wrote:
Wed Aug 28, 2019 2:46 pm
(But the actual wording of your order, and thus the agreement between you, would be of interest here... )

Also, I notice you say " the vendor shipped a 2.5A micro-usb power supply ". Just "a power supply"? Not necessarily an official Raspberry Pi spec Power Supply? The latter, with an adapter, is an option mentioned by Raspberry Pi, as cited.
The order page cited the following;
Raspberry Pi 15W Power Supply, US, Black

The order itself cited the following;
SKU: 1354: MicroUSB Power Supply with USB-C Adapter

With that said, and in spite of displaying the official Pi power supply, I received a 2.5A generic micro-usb power supply with an type-c adapter
When I contacted the vendor to ask about this, I was told that 2.5A was sufficient;
The Raspberry Pi Foundation has confirmed that a good quality 2.5A power supply can be used with the new Raspberry Pi Model 4B as long as the USB peripherals consume less than 500mA in total. We have tested our 2.5A power supply with the 4B board, and it works well. So we have made it available with adapters as a budget solution. It's very convenient as it can be used for all board models!

Please let us know if you have any more questions.
Needless to say, the thought of a manufacturer recommending one thing and a vendor stating otherwise does raise questions.

Smalltimer
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 4:15 pm

I just wanted to add that I received an official response from raspberrypi.org on matters;

Hi
Ignore the previous email, the new Raspberry Pi 4 needs more juice than previous models - You'll need an official 5.1V 3A power supply (or equivalent).

Kind Regards
​Emma

With that said, I have forwarded this to the vendor, with the expectation of having my order corrected.
Otherwise, I'll just return the order in favor of finding another vendor.

Thanks for the help

W. H. Heydt
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 7:24 pm

Smalltimer wrote:
Wed Aug 28, 2019 3:51 pm
B.Goode wrote:
Wed Aug 28, 2019 2:46 pm
(But the actual wording of your order, and thus the agreement between you, would be of interest here... )

Also, I notice you say " the vendor shipped a 2.5A micro-usb power supply ". Just "a power supply"? Not necessarily an official Raspberry Pi spec Power Supply? The latter, with an adapter, is an option mentioned by Raspberry Pi, as cited.
The order page cited the following;
Raspberry Pi 15W Power Supply, US, Black

The order itself cited the following;
SKU: 1354: MicroUSB Power Supply with USB-C Adapter

With that said, and in spite of displaying the official Pi power supply, I received a 2.5A generic micro-usb power supply with an type-c adapter
When I contacted the vendor to ask about this, I was told that 2.5A was sufficient;
The Raspberry Pi Foundation has confirmed that a good quality 2.5A power supply can be used with the new Raspberry Pi Model 4B as long as the USB peripherals consume less than 500mA in total. We have tested our 2.5A power supply with the 4B board, and it works well. So we have made it available with adapters as a budget solution. It's very convenient as it can be used for all board models!

Please let us know if you have any more questions.
Needless to say, the thought of a manufacturer recommending one thing and a vendor stating otherwise does raise questions.
While your vendor's statement is correct, as far as it goes, they shipped you a part that doesn't match what you ordered. It is on that basis alone that I would insist on getting what I ordered, even if what was shipped is "good enough". What they've done is usally called "bait and switch", and--at least where I live--is illegal.

alphanumeric
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 8:37 pm

https://www.raspberrypi.org/documentat ... pi-power

Product > Raspberry Pi 4 Model B
"Recommended" PSU current capacity > 3.0A
Maximum total USB peripheral current draw > 1.2A
Typical bare-board active current consumption >>> 600mA <<<


No issues here running my 4gig Pi 4B from the Official Micro USB 2.5A supply with the USB C adapter.

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Imperf3kt
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 9:43 pm

Smalltimer wrote:
Wed Aug 28, 2019 3:51 pm
The order page cited the following;
Raspberry Pi 15W Power Supply, US, Black

The order itself cited the following;
SKU: 1354: MicroUSB Power Supply with USB-C Adapter
You got what you ordered, a 2.5A power supply with adaptor to usb-c

A 3A USB-C power supply would have been 18W and would not require an adaptor.


That said, it should still be more than sufficient.
Last edited by Imperf3kt on Wed Aug 28, 2019 9:51 pm, edited 2 times in total.
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52:4C:52:42:41

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davidcoton
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 9:46 pm

Imperf3kt wrote:
Wed Aug 28, 2019 9:43 pm
A 3A USB-C would have been 18W and not needed an adaptor.
2A5 at 5V0 is 12W50
2A5 at 5V1 is 12W75
3A0 at 5V0 is 15W00
3A0 at 5V1 is 15W30

Where do you get 18W? :shock: :roll:
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Imperf3kt
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 9:49 pm

davidcoton wrote:
Wed Aug 28, 2019 9:46 pm
Imperf3kt wrote:
Wed Aug 28, 2019 9:43 pm
A 3A USB-C would have been 18W and not needed an adaptor.
2A5 at 5V0 is 12W50
2A5 at 5V1 is 12W75
3A0 at 5V0 is 15W00
3A0 at 5V1 is 15W30

Where do you get 18W? :shock: :roll:
A miscalculation....

Please ignore my previous reply.
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52:4C:52:42:41

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FTrevorGowen
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Re: Is 2.5A enough for the Pi 4?

Wed Aug 28, 2019 10:29 pm

FWIW, measurements of the current loading behaviour of, albeit single samples, of all three versions of "Official Pi PSU's" can be found here:
http://www.cpmspectrepi.uk/raspberry_pi ... ec.2018.29
Whilst my P4B is usually powered by this USB C PSU: http://www.cpmspectrepi.uk/raspberry_pi ... .2FCharger (acquired before the official 3A PSU's became available) it has also been powered by the 2.5A PSU + adapter "AH" shown here: http://www.cpmspectrepi.uk/raspberry_pi ... pterCables
Trev.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, A+ and a B2) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

hippy
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Re: Is 2.5A enough for the Pi 4?

Thu Aug 29, 2019 2:03 pm

W. H. Heydt wrote:
Wed Aug 28, 2019 7:24 pm
While your vendor's statement is correct, as far as it goes, they shipped you a part that doesn't match what you ordered. It is on that basis alone that I would insist on getting what I ordered, even if what was shipped is "good enough". What they've done is usally called "bait and switch", and--at least where I live--is illegal.
+1

Who was this vendor ? Other purchasers would be advised to steer clear of those who engage in such practices.

Smalltimer
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Re: Is 2.5A enough for the Pi 4?

Thu Sep 05, 2019 2:24 am

I wanted to update my results for anyone facing a similar problem in the future.
The first thing to notes is that I was contending with two separate issues;

The first issue was due to a power supply insufficiency, which was causing HDMI signal failure.
The second issue was due to a faulty or micro-SD card, that was defective or fraudulent, causing the Pi to be very slow.

With that said, here are my observations associated regarding those two issues;

1. When I used the power supply sent by the seller(12 watt generic), the Pi would only boot with smaller screens such as 17" LCD or less - whereas larger screens such as; a 50" LED TV, or 32" LCD monitor are not working properly - ie; the TV along with the 32" computer monitor will not register no signal and go to sleep, whereas the 27" LCD will work intermittently (going to sleep randomly)

However and with that being said, upon using the very same setup(screens) with the official Pi 4, 15.3 Watt PSU, all of the screens worked without without issue.

I have tested this thoroughly over and over again, and so if anyone is facing screen signal output issues, then I'd recommend checking your power-supply first and foremost.

In addition to this, I'd also add, that there were no power signal warnings displayed on the UI at any time when the HDMI signals were failing. And so it would appear that the low power signal is not tied-in directly to the quality of the HDMI signal.

2. As for the micro SD card, this was a much simpler fix, I ordered a Samsung EVO Plus 64 GB and everything livened-up quite nicely - the original card I was using was most definitely defective, and the UI would stop periodically during normal operation - swapped-out the card, and everything runs normally now.

- hope this helps, as this was an enlightening lesson on my part
Last edited by Smalltimer on Fri Sep 06, 2019 6:43 am, edited 3 times in total.

Smalltimer
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Re: Is 2.5A enough for the Pi 4?

Thu Sep 05, 2019 2:31 am

hippy wrote:
Thu Aug 29, 2019 2:03 pm
Who was this vendor ? Other purchasers would be advised to steer clear of those who engage in such practices.
I purchased this from buypi.ca

Though I must say that I am quite disappointed by the quality of care as they vendor chose to ignore my requests for a refund on the power supply to make things right.

- I have since opened a Paypal dispute to get my money back
Last edited by Smalltimer on Thu Sep 05, 2019 2:37 am, edited 1 time in total.

Smalltimer
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Re: Is 2.5A enough for the Pi 4?

Thu Sep 05, 2019 2:35 am

Imperf3kt wrote:
Wed Aug 28, 2019 9:43 pm
That said, it should still be more than sufficient.
Testing shows that 12.5W was not enough to power the HDMI signal on certain monitors.
During testing I found that swapping a working system to the lower power psu results in HDMI signal loss, whereas the official 15.3 W power supply works without issue.
Last edited by Smalltimer on Fri Sep 13, 2019 3:30 am, edited 1 time in total.

drgeoff
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Re: Is 2.5A enough for the Pi 4?

Thu Sep 05, 2019 9:48 am

Smalltimer wrote:
Thu Sep 05, 2019 2:24 am
When I used the power supply sent by the manufacturer(12 watt generic), the Pi would only boot with a smaller screen such as 17" LCD or less - but would not work with larger screens with TV's or LCD monitors such as a 24" or 32" computer screen.
I don't dispute your specific findings with your specific displays. But I would dispute your implication that TVs/monitors with larger screens need more "power" from a RPi than smaller ones.

Timescale
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Re: Is 2.5A enough for the Pi 4?

Thu Sep 05, 2019 3:17 pm

Meh, Headless without any peripherals attached to USB, it works.. Otherwise just get the proper 3amp brick.

W. H. Heydt
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Re: Is 2.5A enough for the Pi 4?

Thu Sep 05, 2019 3:32 pm

Timescale wrote:
Thu Sep 05, 2019 3:17 pm
Meh, Headless without any peripherals attached to USB, it works.. Otherwise just get the proper 3amp brick.
Well...yes. But the root of the OPs problem is that he ordered a proper 3A PSU only to be shipped a 2.5A PSU and a microSUB-B to USB-C adapter. He tried to do it correctly only to get hosed by the vendor.

bjtheone
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Re: Is 2.5A enough for the Pi 4?

Fri Sep 06, 2019 2:08 am

Smalltimer wrote:
Thu Sep 05, 2019 2:31 am
hippy wrote:
Thu Aug 29, 2019 2:03 pm
Who was this vendor ? Other purchasers would be advised to steer clear of those who engage in such practices.
I purchased this from buypi.ca

Though I must say that I am quite disappointed by the quality of care as they vendor chose to ignore my requests for a refund on the power supply to make things right.

- I have since opened a Paypal dispute to get my money back
Interesting. We have bought lots of Pis from them for Robotics without any issues. I ordered my 4B 4GB from them with the official USB C P/S and indeed received the official P/S. Possibly they ran short and decided to substitute or perhaps it was due to the fact that I picked it up at the storefront. Either way I would not accept a 2.5A P/S and micro to C adapter. The adapter will result in further losses. It is not a like for like substitution. However, as other folks have pointed out, a decent 2.5 A P/S should run an 4B unless you max out the load on the USB ports. My 4B runs fine off my 3B+ official P/S with an adapter, with a SSD attached.

I tend to order from CanaKit and BuyaPi since they both have Canadian store fronts. Duty, exchange, and shipping from US sites gets ugly real quick.

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