Featured Articles
Announcing Pi
Technical Specifications
Raspberry Pi FAQs
Win a Pi
Raspberry Pi Wishlist
Actions
Forum Thread Details
  • Replies 12 replies
  • Subscribers 678 subscribers
  • Views 7632 views
  • Users 0 members are here
Related

Pi3 shows yellow lightning bolt with official power supply

chaozz

I got a Raspberry Pi 3 from TinyDeals to review on my Youtube channel. However, when I run Raspbarian (I tried two different SD cards) or RetroPie I get a yellow lightning bolt in the top right corner. I understand this means "undervoltage".

 

I am using the official Raspberry power supply (I have two, brand new) and tried different phone chargers all with the same result. I have also tried different SD cards and don't have anything plugged into the USB ports.

 

Is my unit broken?

 

PS: I am also a bit disappointed I won't be able to do a review of the Pi, since I won't be able to get warranty on this device (and bought a case and power supply for nothing). image

Parents

  • Yes, the yellow lightning bolt means "undervoltage". Normally "its right about it", i.e. when it says it's undervolting, that is usually the case.

     

    The good news is that the pi itself will work just fine (and within spec) down to about 3.3V on the 5V input rails. The bad news is that HDMI devices that expect to be powered with 5V from the PI like the HDMI->VGA adapter that I have, will not be happy. Similarly, USB devices that are bus-powered will usually not like this situation.

     

    As you have an HDMI screen (you see the yellow bolt), and don't need an HDMI->VGA adapter, and you can use a powered USB hub for USB devices that you need, the pi can still be tested.

     

    But.... Before you go blaming the pi... I would recommend you test if the pi is "lying" or not. What is your 5V powersupply delivering? On the GPIO connector, nearest the corner, you find a pin with 5V (pin2). The pin along the edge of the PCB is another 5V pin (pin4). The next one is "GND". So get out a multimeter and measure it. Are you getting less than 4.75V ? Then the pi is right when complaining about low voltage level....

  • in reply to rew

    I tested pins 2 and 4 on the GPIO, and they both give 5.22volts when booted up (no USB devices connected). Any ideas?

  • in reply to chaozz

    Well... in that case, it seems that your pi is "lying" to you that the power is not sufficient. Just ignore the lightning bolt.

     

    In practice I still find this such an odd "defect" to have, that I suspect that your powersupply is not coping enough with the sudden bursts of required power that the power dips below 4.65V very shortly, so that your multimeter cannot detect them.     

     

    You say you bougth a powersupply specifically for the pi? Did you get the one from Element14 with the attached micro usb cable, or a different one?

    The resistance of USB cables varies a LOT. I've done a measuring session, and the worst had a resistance of 6.5 Ohms, so at 0.5A (the pi3 can exceed that), you'd get a voltage drop of 3.25V, start out with 5.25 and there will be only 2V left, too little to run a pi. But even a 1 Ohm cable will not cope well with the spikes possibly triggering exactly what you are seeing.....

  • in reply to rew

    I can not ignore it, because none of the USB devices I connect work. The same setup works fine on my Pi Zero.

     

    Here is the power supply I am using, with a fixed cable: https://www.kiwi-electronics.nl/raspberry-pi/raspberry-pi-stroomvoorzieningen/rpi-psu-5-1v-2-5a--eu-uk

Reply Children
No Data