Endgame
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Power efficiency of official power supply?

Thu Oct 01, 2020 4:53 pm

Does anyone know how efficient the official pi 4 power supply is? I know usb power bricks can vary greatly in power efficiency, and I'm really looking for something in the 90%+ efficient range for my pi 4s, and 95% efficiency would be fantastic. Ex: say my pi is pulling around 10 watts - at 90% efficiency the power brick should be pulling 11w from the wall.

Additionally, does anyone have a recommendation for a high efficiency, multi port adapter (ex, 6x ports). I'm currently using one of these, but, at best, its 85% efficient per Anker support

https://www.amazon.com/Anker-Charger-Po ... B00P936188

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jahboater
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Re: Power efficiency of official power supply?

Thu Oct 01, 2020 5:02 pm

I cant find a datasheet for the Pi4 PSU that 99.99999% of people use.
Here it is for the older Pi3 PSU:
http://www.farnell.com/datasheets/2020879.pdf
80.86%
Pi4 8GB running PIOS64 Lite

trejan
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Re: Power efficiency of official power supply?

Thu Oct 01, 2020 5:07 pm

jahboater wrote:
Thu Oct 01, 2020 5:02 pm
I cant find a datasheet for the Pi4 PSU.
Yeah. For some odd reason, the raspberrypi.org product page doesn't have the datasheet but you can find it on the RS product page for it.
Efficiency:

81% minimum (output current from 100%, 75%, 50%, 25%)
72% minimum at 10% load

Endgame
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Re: Power efficiency of official power supply?

Fri Oct 02, 2020 1:33 pm

That's a shame the official power supply is so low. Does anyone have any leads on 90% + efficiency supplies?

pidd
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Re: Power efficiency of official power supply?

Fri Oct 02, 2020 1:54 pm

Endgame wrote:
Fri Oct 02, 2020 1:33 pm
That's a shame the official power supply is so low. Does anyone have any leads on 90% + efficiency supplies?
It might be worth you doing some measurements at your typical load levels, at 2A load it might be around the 90% efficiency mark or higher. They are specifying 81% over the 25% to 100% load range which is a big range for an efficiency spec as can be seen by them reducing efficiency spec to 72% at 10% load. There will be a sweet-spot where it is most efficient.

I am quite concerned at the relatively low load regulation figure of 5%, this means the 5.1V supply might not achieve 4.85V at full load.

I suspect the figures are very conservative.

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jahboater
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Re: Power efficiency of official power supply?

Sat Oct 03, 2020 9:11 am

pidd wrote:
Fri Oct 02, 2020 1:54 pm
I suspect the figures are very conservative.
Very likely.

I am impressed by the simple fact that the detailed spec is actually published.
Pi4 8GB running PIOS64 Lite

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Imperf3kt
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Re: Power efficiency of official power supply?

Sun Oct 04, 2020 2:37 am

pidd wrote:
Fri Oct 02, 2020 1:54 pm


I am quite concerned at the relatively low load regulation figure of 5%, this means the 5.1V supply might not achieve 4.85V at full load.

I suspect the figures are very conservative.
I suspect the 5.1v figure is not accurate.
I have two official power supplies and both measure 5.25v at the Pi end.
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achrn
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Re: Power efficiency of official power supply?

Sun Oct 04, 2020 5:38 am

pidd wrote:
Fri Oct 02, 2020 1:54 pm

I am quite concerned at the relatively low load regulation figure of 5%, this means the 5.1V supply might not achieve 4.85V at full load.
When I tested an older official PSU it showed a linear characteristic from about 5.2V at 200mA to 4.7V at 3.4A, so at 2A it was about 4.95V.
My write-up is at http://www.astounding.org.uk/ian/raspi- ... _test.html and the data is in http://www.astounding.org.uk/ian/raspi- ... plies.xlsx

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FTrevorGowen
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Re: Power efficiency of official power supply?

Sun Oct 04, 2020 8:40 am

achrn wrote:
Sun Oct 04, 2020 5:38 am
pidd wrote:
Fri Oct 02, 2020 1:54 pm

I am quite concerned at the relatively low load regulation figure of 5%, this means the 5.1V supply might not achieve 4.85V at full load.
When I tested an older official PSU it showed a linear characteristic from about 5.2V at 200mA to 4.7V at 3.4A, so at 2A it was about 4.95V.
My write-up is at http://www.astounding.org.uk/ian/raspi- ... _test.html and the data is in http://www.astounding.org.uk/ian/raspi- ... plies.xlsx
FWIW, you may find these "current loading" measurements (and others linked to therein) of interest:
https://www.cpmspectrepi.uk/raspberry_p ... _Models.29
Trev.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, 2xB2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, and a A+) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

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