I am in process making Raspberry Pi 3B my primary development system.

I am experimenting with adding USB devices, with some success. With several USB device connected via EXTERNALLY powered USB hub I have some minor issues with them, but NO POWER issue as far as I can tell.

BUT after going back to minimal configuration - only USB wireless adaptor connected - I started getting this lightning bolt ALMOST every time the monitor changes. ( No , changing the monitor intensity IS NOT an option , I am looking for an answer , not "try this " band-aid) The power indicator red LED stays on full time and I am still using SAME main power supply.

It sure looks as the monitor "power" also runs FROM USB devices and NOT only from the main power.

This is not a big issue, since it works fine when / with externally powered USB hub I'll be using anyway. I just like to have some clarification why is this happening on "bare bones" Pi.

Please , no "use official power supply by...." , I appreciate if you read the post before replying canned way and not waste your and mine time.


  • What do you mean by a lightening bolt and by monitor changes. Also could you tell us what this USB wireless adaptor is? Knowing its power requirements would help. – pfl Jul 5 '17 at 15:20
  • I'll run the USB adaptor via POWERED USB port and can post the results here. I cannot tell the adaptor power , I have not found a command to do that, still looking. I understand this forum is not a discussion forum , so I also cannot tell you what is LXPanel lightening bolt is. Sorry. – Jan Hus Jul 5 '17 at 17:00

This simply means that your PI isn't getting the power it requires. This can be due to many factors, but it is quite clear that your adapter is pulling more power through the USB than the power supply can output with both the pi AND the adapter working simultaneously. Running too long like this will ruin the board permanently. Using the PROPER power supply is the only way to ensure you're going to get the power required to your PI. NO, you DON'T need the official PI power source. It is sold to support the RPI Foundation. You can go onto Ebay, and find a really nice 5v/3a power supply fur under $5 (not including shipping in some cases). I bought 4 of them to power my PI devices.

| improve this answer | |
  • Sorry, not what I am looking for. Please read the OP. – Jan Hus Jul 5 '17 at 16:58
  • 1
    I wouldn't have answered the OP Had I not read it. The answer you got from me IS the answer you need. The lightning bold that appears in the upper right hand side of your display is the "insufficient power" indicator...the only way this will happen is if: 1) You have an insufficient power supply for the Pi. 2) You have too many devices connected consuming power (via any means i.e. USB, GIPO, etc.) 3) There is a combination between the two. Here is something to help you: raspberrypi.org/forums/… – PiGuy88 Jul 6 '17 at 19:07
  • Is it possible that this behavior is being caused by the combination of an inadequate power supply AND the RPi being back-powered via the USB hub while it's connected? Do you get the bolt with the bare RPi without the USB wireless adapter? If so, then that confirms it's the power supply. In either case, it sounds like the answer is an adequate power supply as @PiGuy88 notes. – bobstro Jul 7 '17 at 15:28
  • @bobstro, Doubtful that the first part of your comment is the case. Although you can back-power a Raspberry Pi, you will actually hurt the Pi by doing this [intentionally]. The fuse for the USB ports can only handle a small amount of power (in which the USB hub is too powerful for). Also, if you you were to back-power the pi in accompaniment of the micro USB power source, theoretically, you should be boosting the total power coming into the pi and possible eliminating the Lightning Bolt. JanHus, what do you mean by "Monitor Changes"? – PiGuy88 Jul 7 '17 at 23:17
  • @PiGuy88 could a faulty hub still do it though? It might be interesting to see if the results are the same using a different powered hub. – bobstro Jul 8 '17 at 1:29

Not the answer you're looking for? Browse other questions tagged or ask your own question.