I'm using a USB 7 port hub that's rated 5V at 3.0A and get a lightning bolt symbol in Raspbian. There's nothing else plugged into it.

Shouldn't this work?


  • 3
    The USB 2.0 spec says that they need to supply only 0.5 Amp per port. So no it may not work, as in your case. The cable could also be the source of the problem. – Steve Robillard Apr 24 '17 at 0:21
  • I'll try another cable, I have a few for the cell phones. If none work, I'll get an adapter from adafruit. – user1598226 Apr 24 '17 at 2:18
  • It was the cable. I tried the powered hub after a 2A adapter didn't work. The 2A now works. Thanks! – user1598226 Apr 24 '17 at 19:44
  • Now it's giving me the lightning bolt again. Nothing changed. – user1598226 Apr 27 '17 at 3:39
  • The answer is the same better power supply. Not a USB hub )powered or unpowered). Likely the other cable was a marginal fix. – Steve Robillard Apr 27 '17 at 3:41

Your PSU isn't powerful enough. Try the official Raspberry Pi PSU. Also try plugging in a power adaptor to your USB hub if it has a jack.

  • The hub is plugged in. – user1598226 Apr 24 '17 at 2:16
  • @user1598226 it is possible that the hub will only supply 500ma to each USB port which is what is stated in the USB spec – Mohammad Ali Apr 30 '17 at 19:36

Lightning bolt means undervoltage.

Measure the voltage you're getting out of your hub (with a multimeter, USB charge monitor, whatever) and on the power pins of your RPi. Either your hub is not supplying a high enough voltage, or your cable is bad enough to drop the voltage on the RPi side.

Also, a "3A" label doesn't magically turn a bad power supply into a good one.

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