under voltage

Using the latest version of server on Pi 3b. Was using an extremely high quality walwart power supply without problem for several months. Then started getting 'under voltage' warnings so I bought a Meanwell 90-watt 5-volt power supply and adjusted voltage to 5.1 and still have same problem. Now says 'under voltage' all the time.  

What am I doing wrong?


  • more information that might help. I have changed the USB cable, and the micro SD card. This low voltage is combined with 'CPU throttled' and lasts about 20 minutes and then the reading is 'under voltage in past'
  • Just to be clear - we only show the signals that linux produced as many problems come from power problems. That does not necessarily mean you have these problems. I have 2 pis with same message every now and then and they are absolutely stable none the less.

    Of course if you get randomly problems that is source 1 to look for. Guess it depends how bid the undervoltage really is. You might prevent powering printer as described here: 

    that reduces load on power a bit. Also usb cable for power needs good diameter for power lines or resistance reduces voltage that receives the board.
  • Thanks for the reply.

    The Prusa Rambo using the power not a problem since I get the error when booting the Pi even if the Prusa printer is turned off.

    Two things make me concerned: after many months of no voltage errors, I now get it all the time and after some time the 'now' becomes 'in the past' but if I 'restart' the Pi (not reboot) the error returns to 'now'

    Could the Pi be going weak or bad? Is it better to use a Pi 3 or a Pi 4?
  • At startup cpu load is high, so that explains why you only get it at startup. Prusa Rambo in deed uses nearly no power, so no issue anyway. Guess when you render images it might come on again. But as long as it does not cause problems I would ignore it. Maybe you have a newer kernel that triggers earlier. Don't really think the pi is bad - that is unfortunately a frequent issue.
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