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I have a Raspberry Pi 3 Model B and it seems like it's always low on power. You can see this by the lightning bolt on the top right corner.

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I started out by plugging the USB power into a 1A iPhone charger. It worked but the lightning bolt was always there. Then I tried a 2.1A port and the lightning bolt was still there for a majority of the time (any time I clicked or while the Pi was opening an application, while idle it would go away)

I guess I have two questions:

  1. What is the minimum power a Raspberry Pi needs to completely remove the low-power indicator?
  2. What type of issues will you run into if they Pi has low power for an extended amount of time?

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    Hello! Yes, there is a RPi.SE and you'Re cordially invited! The questions of power consumption and the low voltage issue (the lightning bolt) have been asked and answered before. If the Pi reports low voltage with a power supply that should provide 2 amps or more it usually is a problem with poor cabling. There are really bad micro-USB cables out there. – Ghanima Mar 22 '17 at 17:01
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    See Raspberry Pi Power Limitations You need a quality Power Supply NOT a charger, and a decent cable. – Milliways Mar 22 '17 at 23:03
  • NOTE The lightning bolt is NOT a low power indicator, although it is often called this. It is a low voltage indicator. – Milliways Mar 23 '17 at 3:37
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First off the raspberry Pi corporation has not realeased a model "3+" so assuming that you are using a model "3" the power requirements from the official FAQ located Here state that 2.5 amps is the recommended USB power supply current capacity. Which is higher than the 2.1 amp supply that you have which means that you should likely upgrade to a power supply capable of delivering a higher amount of current. Also I would personally recommend that you stay away from off brand power supplies as they aren't usually designed to operate 24/7 and are usually unreliable. Furthermore to answer your second question if your Pi has low power for an extended amount of time you may face unexpected shutdowns which can corrupt your SD card. If you wish to remove the low power warning without changing your set up you could also try lowering the clock speed of the Pi, google "disabling turbo mode on the Pi"

  • Also, the shorter the length of the USB cable the better, ALWAYS. Use an extension cord from the socket to the transformer rather than a longer USB cord. – Sandor Dosa Mar 22 '17 at 17:12
  • This answer perpetuates the SD Card myth. The SOC and SD Card run from 3.3V supplied by an on-board regulator, so the voltage would have to be VERY low for the SD card to be affected. – Milliways Mar 22 '17 at 23:10
  • @Milliways I'm not trying to imply that low voltage will damage the sd card. What I'm saying is that low current/voltage may cause unexpected shutdowns which may damage the sd card – Mohammad Ali Mar 22 '17 at 23:53
  • @MohammadAli Have you tried it? The Pi will run on less than 4V. The question was not about running with batteries. – Milliways Mar 22 '17 at 23:57
  • @Milliways I was referring to the Pi unexpectedly shutting off due to low current – Mohammad Ali Mar 23 '17 at 3:27
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I enjoy trying to understand power consumption as some of my projects rely on battery power and I need to know how long it is going to last.

So, here is my attempt at answering your questions.

  1. What is the minimum power a Raspberry Pi needs to completely remove the low-power indicator?

It depends. The Raspberry Pi 3 can use anywhere from 230mA when idle, to 350mA when using the camera, to 720mA when using all 4 cores of its CPU and that is not counting any additional draw from USB devices.

So to quote RaspiTV: "It’s important to understand that the 2.5A is specified to work in pretty much all circumstances you can think of. But in many cases, a bit less will be OK, depending on what you’ve got plugged into your Pi."

If you are interested to learn more, here is a great analysis from RaspiTV.

  1. What type of issues will you run into if they Pi has low power for an extended amount of time?

I think the biggest issue is if the Pi turns off or reboots as the SD Card could get corrupted or even damaged.

  • This answer perpetuates the SD Card myth. The SOC and SD Card run from 3.3V supplied by an on-board regulator, so the voltage would have to be VERY low for the SD card to be affected. – Milliways Mar 22 '17 at 23:10
  • How about so VERY low so that the Pi turns off or reboots. That is what I said. Here is a nice explanation on potential issues: "One of the main hazards associated with running a Raspberry Pi from a battery is the potential to damage the Pi if it is abruptly turned off. The operating system must be safely shut down before power is removed from the Pi or the SD card (or the Pi board itself) may be permanently damaged." – Ricardo Mar 22 '17 at 23:51

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