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I bought the Official power supply but when I use it in my Pi 3 model B I get a warning saying: "low voltage, please check power supply".

I have checked the voltage on the Pi using a multimeter and it displays 5.2 V, suggesting that it shouldn't be an issue with the power supply.

It has a fresh install of Raspberry Pi OS and the only things connected are a mouse, keyboard and a HDMI output to a monitor.

Are you able to help in any way with diagnosing/fixing the issue with the Pi?

JonasVautherin
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Cai
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4 Answers4

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Try getting a shorter / thicker / better quality USB cable to connect the Pi to the PSU. Poor cables can produce all sorts of weird behavior which sometimes only manifest when the current exceeds a certain value or the cable is bent just the right way, while 99% of the time the connection is OK and voltage measurement looks fine.

Also, make sure you measure the voltage on the 5V pin on the GPIO connector, not with some sort of power monitor connected in series with the cable. When the Pi is disconnected, you should measure 0V there, not 5.24V.

Dmitry Grigoryev
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Checking the voltage with a multimeter isn't that useful. If it shows high that is a integrated measurement made at a point of time. It tells you nothing about the voltage which triggered the low voltage warning.

Try the following

  1. a different power supply
  2. a different power cable
  3. a different Pi
joan
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where are you measuring the voltage?

what software is running when the message shows?

How to rule out the peripherals (keybd mouse hdmi):

set up remote-login to the PI (like ssh).

unplug everything, including the keyboard, mouse, and HDMI


boot the pi


connect remotely to pi with ssh (putty on windows)


now run 'dmesg -T' from the command line


if there are no low voltage errors in the dmesg log, it means its your mouse, keyboard, or hdmi was causing the problem.


if there are still low voltage errors in the dmesg log, it means something in your pi or power supply wires/usb jack is not working.
don bright
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EDIT: Thanks to some help I got in comments, I learned that this is not a good answer for this question. The descriiption in this answer does not describe an anomoly or bug in the undervoltage warning (yellow lightning bolt). Although it's not a helpful answer to this question, it was pointed out that someone who has observed this "discrepancy" might find this "answer".

When you saw the undervoltage lightning bolt, was that on a monitor plugged into the HDMI connector on the RPi, or was it on a VNC connection? I have had both the HDMI into a monitor and VNC over WiFi to a laptop at the same time, but the lightning bolt only appeared on one of them (I think it was on the HDMI). Given the number of power supplies I tried, as well as numerous other such experiences people have posted, and the contradiction between HDMI and VNC, I am inclined to suspect that the problem is with the RPi.

TRS-80
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