Raspberry Pi Forums

Posted: **Fri Aug 14, 2020 10:56 am**

Hi all!

I have a Samsung EP-TA20BWB (sure original, came with my S7) plugged in a Rasp Pi 4 rev 1.2 as NAS. The power supply has a very stable voltage output across loads, constant 4.99 - 5.01 V (tested here)! No yellow ray!

Reading this analysis (I believe is not fake - links below), this power supply can deliver more than 3.0A at stable 5V!

Can this power supply be reliable to use with a Raspberry Pi 4 with light use, with a Argon Neo case without a fan, a external HDD pulling 1A only at start spinning (which is OK for PSU which can deliver a 3.0A for short period), only 1.7W for read/write and a 100mA Logitech Keyb/Mouse combo?

Rpi 4 core - 1.2A (Max stress, well above light average 0.6A use)
+
HDD running - 0.5A
+
Keyb/mouse combo - 0.1A
=
Total (stress) - 1.8A
Total (typical) - 1.2A
Total (booting, HDD starting) - 1.7A

https://www.raspberrypi.org/documentati ... /README.md

https://www.raspberrypi.org/blog/therma ... 203%20B%2B.

https://lygte-info.dk/review/USBpower%2 ... %20UK.html

https://lygte-info.dk/review/USBpower%2 ... %20UK.html

Posted: **Fri Aug 14, 2020 11:12 am**

melqui wrote: ↑
Fri Aug 14, 2020 10:56 am
Hi all!

I have a Samsung EP-TA20BWB (sure original, came with my S7) plugged in a Rasp Pi 4 rev 1.2 as NAS. The power supply has a very stable voltage output across loads, constant 4.9 - 5.0 V (tested here)! No yellow ray!

Reading this analysis (I believe is not fake - links below), this power supply can deliver more than 3.0A at stable 5V!

Can this power supply be reliable to use with a Raspberry Pi 4 with light use, as NAS with a Argon Neo case without a fan, a external HDD pulling 1A only at start spinning (which is OK for PSU which can deliver a 3.0A for short period) but only 1.7W for read/write and a 100mA Logitech Keyb/Mouse combo? (Rpi 4 core power consumption at Max stress is about 1.2A, average 0.6A)

Rpi 4 - 1.2A (Max stress, well above light 0.6A use)
HDD running - 0.5A
Keyb/mouse combo - 0.1A

Total (stress) - 1.8A
Total (typical) - 1.2A
Total (booting, HDD starting) - 1.7A

https://www.raspberrypi.org/documentati ... /README.md

https://lygte-info.dk/review/USBpower%2 ... %20UK.html

https://lygte-info.dk/review/USBpower%2 ... %20UK.html

Personally bought the Official PSU, therefore no issues, great value:

https://www.raspberrypi.org/products/ty ... er-supply/

Posted: **Fri Aug 14, 2020 11:15 am**

fruitoftheloom wrote: ↑
Fri Aug 14, 2020 11:12 am

melqui wrote: ↑
Fri Aug 14, 2020 10:56 am
Hi all!

I have a Samsung EP-TA20BWB (sure original, came with my S7) plugged in a Rasp Pi 4 rev 1.2 as NAS. The power supply has a very stable voltage output across loads, constant 4.9 - 5.0 V (tested here)! No yellow ray!

Reading this analysis (I believe is not fake - links below), this power supply can deliver more than 3.0A at stable 5V!

Can this power supply be reliable to use with a Raspberry Pi 4 with light use, as NAS with a Argon Neo case without a fan, a external HDD pulling 1A only at start spinning (which is OK for PSU which can deliver a 3.0A for short period) but only 1.7W for read/write and a 100mA Logitech Keyb/Mouse combo? (Rpi 4 core power consumption at Max stress is about 1.2A, average 0.6A)

Rpi 4 - 1.2A (Max stress, well above light 0.6A use)
HDD running - 0.5A
Keyb/mouse combo - 0.1A

Total (stress) - 1.8A
Total (typical) - 1.2A
Total (booting, HDD starting) - 1.7A

https://www.raspberrypi.org/documentati ... /README.md

https://lygte-info.dk/review/USBpower%2 ... %20UK.html

https://lygte-info.dk/review/USBpower%2 ... %20UK.html

Personally bought the Official PSU, therefore no issues, great value:

https://www.raspberrypi.org/products/ty ... er-supply/

I too, waiting to arrive!

But this specific charger looks good, very stable voltage!

Posted: **Fri Aug 14, 2020 11:22 am**

A question to experts: is possible a bug in firmware (for example) activate the QC 9V or is impossible actually with only software (need hardware)?

https://youtu.be/UYRZ0t5eyjE

Posted: **Fri Aug 14, 2020 5:25 pm**

melqui wrote: ↑
Fri Aug 14, 2020 11:22 am
A question to experts: is possible a bug in firmware (for example) activate the QC 9V or is impossible actually with only software (need hardware)?

https://youtu.be/UYRZ0t5eyjE

Hit a Pi with 9v and the next thing you'll be doing is buying a replacement Pi.

Posted: **Fri Aug 14, 2020 5:52 pm**

W. H. Heydt wrote: ↑
Fri Aug 14, 2020 5:25 pm

melqui wrote: ↑
Fri Aug 14, 2020 11:22 am
A question to experts: is possible a bug in firmware (for example) activate the QC 9V or is impossible actually with only software (need hardware)?

https://youtu.be/UYRZ0t5eyjE
Hit a Pi with 9v and the next thing you'll be doing is buying a replacement Pi.

Sure!

so i would like to know if there is the possibility to activate 9v via software, just to be sure that it will not be activated by a possible software bug.

Posted: **Fri Aug 14, 2020 6:57 pm**

melqui wrote: ↑
Fri Aug 14, 2020 5:52 pm

W. H. Heydt wrote: ↑
Fri Aug 14, 2020 5:25 pm

melqui wrote: ↑
Fri Aug 14, 2020 11:22 am
A question to experts: is possible a bug in firmware (for example) activate the QC 9V or is impossible actually with only software (need hardware)?

https://youtu.be/UYRZ0t5eyjE
Hit a Pi with 9v and the next thing you'll be doing is buying a replacement Pi.
Sure!

so i would like to know if there is the possibility to activate 9v via software, just to be sure that it will not be activated by a possible software bug.

AIUI a P4B does not negotiate any "Power Delivery" but "signals" by hard-wired-resistors that it is a (passive) 5V device that expects to be supplied with up to 3A (No software involved). But that's for the "standard" USB 'C' Power Delivery. How that relates to the QualComn method IJDK. The safest and most reliable option is to invest in an official PSU. The only USB 'C' PD supply I personally know works fine is this one: http://www.cpmspectrepi.uk/raspberry_pi ... .2FCharger with a suitable cable, used before the official USB 'C' PSU became available.
Trev.

Posted: **Fri Aug 14, 2020 8:11 pm**

Initiating QCs higher voltage modes requires active communication between source and sink, it's not going to accidentally engage.

Posted: **Fri Aug 14, 2020 8:37 pm**

dustnbone wrote: ↑
Fri Aug 14, 2020 8:11 pm
Initiating QCs higher voltage modes requires active communication between source and sink, it's not going to accidentally engage.

This ^

As another poster said, there is no power negotiation at all, so QC supplies are fine, as long as they have stable voltage and a good USB cable delivering the power.

Voltage stability is the main issue with chargers, since charging batteries does not require precise voltage regulation. Also, monitoring voltages with a DVM does not give you the whole picture. Chargers may not respond quickly to transient demands, but those are too brief to register on a DVM (you need a scope).

If you can run your system for an extended period of time without any low-voltage warnings, then it's probably okay.

What does the command vcgencmd get_throttled return? If you run that periodically and ever get a non-zero response, then your system has throttled due to either thermal or power issues (the number returned can be used to determine which).

Posted: **Fri Aug 14, 2020 11:10 pm**

use charger at your own risk!

if something bad happens to your RPi based on your insistence.... you are the only one to blame...because:
you bought it,
you plugged it to your RPi, and
you powered it while plugged to the RPi...

if you understand the risk and dont blame others for your action(s).... then that's fine for most of us....

if it works fine and you're happy with it... then that's fine for most of us as well.

Posted: **Sat Aug 15, 2020 12:22 pm**

I run frequently "dmesg" and no "undervoltage" errors. When check USB voltage, stable 5.0V (0.01V variations)

Posted: **Sat Aug 15, 2020 1:56 pm**

then all is well then.... congratulations and have fun!

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