I am able to boot my Raspberry Pi 2 while using a 1A power supply. However, when I try to power my RP2 with a 2.5A or 3A supply, nothing happens - No LEDs light up and I am unable to measure any voltage between micro USB pin 1 (VCC) and ground. The 2.5A and 3A power supplies work great for charging my cell phone/chromebook, so I am pretty sure there is nothing wrong with them. Also, the 2.5A is brand new and supposed to be compatible with the RP2 (http://www.canakit.com/raspberry-pi-adapter-power-supply-2-5a.html).

What is the problem? Am I missing something completely obvious?

UPDATE: The 2.5A power supply successfully powers a friend's RP2

  • What is the voltage on the supplies that aren't working? Are the polarities on the plugs the same as the one that is working?
    – Kolban
    Dec 23, 2015 at 21:30
  • Wait, you're using a microusb cable to charge a chromebook? I'm not familiar with a model that is capable of doing that...
    – Jacobm001
    Dec 23, 2015 at 21:30
  • @Kolban The 2.5A supply is 5V and the 3A supply is 5.25V. None of the power supply plugs have polarity.
    – Tim
    Dec 23, 2015 at 21:41
  • @Jacobm001 It's an HP Chromebook 11
    – Tim
    Dec 23, 2015 at 21:42
  • I have two of those canakit adapters and haven't had any problem with them with B/B+/2 models.
    – goldilocks
    Dec 23, 2015 at 21:57

2 Answers 2


This might be helpful or at least a bit enlightening:


Power supplies even with same specs can vary in performance, not delivering the stated voltage or feature current fluctuations.

If the supplies are of that kind which have interchangeable connector cables you might also try to switch one of those as they can be the source for problems too.

Hope that helps a bit.


I bought a second Raspberry Pi 2 and it works fine with the 2.5V Canakit power supply.

My original Raspberry Pi 2 started failing to boot, even with the 1A power supply. I discovered that I am able to power this Pi by using a bench top power supply connected directly to the GPIO header.

Verdict: The problem is with the power distribution/regulation on the Pi.

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