I just got my Raspberry disconnected from a 1 meter USB cable and then connect an extension USB cable (about 2 meters). Before replacing the cable the Raspberry functioned normally, but after replacing the cable, the green LED flashes and nothing happens. I tried 2 chargers: one 1A and through the gate with a second outlet with Raspberry 2A but this does not have any effect.

  • Does it work when connected to a short cable? If so the long cables are probably losing too much voltage.
    – joan
    Commented Jul 30, 2015 at 9:13
  • Yes! with short cable it work perfectly.. I wondered over low voltage but do not know how to check .. I have a strain gauge, but I do not know how to measure voltage usb Commented Jul 30, 2015 at 9:16
  • 2
    Well, by experiment you have discovered the long cables lose too much voltage. Buy chunkier cables, USB cable wires can be very thin.
    – joan
    Commented Jul 30, 2015 at 9:41

3 Answers 3


If you want to check the current draw over USB, then there are many types of USB voltmeter/ammeters available on eBay, for example:

USB Voltmeter

This may help you track down the problem. However, as joan suggests in the comments, if you must use a 2 meter cable then get a thicker USB cable, so that there is less power drop.


I think you have pretty much done the troubleshooting yourself, the problem is most likely in the cable. It could be a really low quality one, since moving from 1A to 2A doesn't change a thing. Maybe the cable is even broken.

You could try and see of the extension cable works with connecting i.e. your phone to a PC (if it's that kind of cable).

The longer the cable the less efficient it will be, so might as well go for a proper one in your case!


Sorry for late reply,

Problem was not resolved,but it was in cable. I have found better cable and everything is now okay.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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