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Does RPi B+ have high enough power output?

e14 Contributor

I have just bought a RPi B+ and found it cannot power my WD My Passport 1TB USB3 drive. The drive just clicks rather than spins up.

 

I'm hoping that it is something I ma doing wrong. Do all the USB ports on the B+ provide the same power?

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  • 0 in reply to e14 Contributor

    Well, as I said in my first reply: You're going to need a nominal 1.7A for a short while during startup. It is not at all evident that a powersupply marked as 2A is actually able to deliver that...

     

     

    I have a test-rig that allows me to test the current capabilities of power supplies. Most 500mA powersupplies are comfortable at 350mA, and above that the voltage sags too much. Similarly the 2A power supplies that I tested often start to drop out around 1.5A (and sometimes even at 350mA!).

     

     

    On the other hand, there might be a voltage drop across the RPI that the WD drive is not happy about. I'd be able to measure such things if it interests me. But in practise it is more important to get things working. So getting  a slightly larger powersupply might solve things for you.

     

     

    If you're into DIY, you could wire up something that "steals" the 5V from inside your big PC. That's a stable and accurate 5V capable of delivering at least around 10A. If it works on there, a better power supply might help. If it doesn't the voltage drop across the 'pi is too much anyway. This is just a suggestion that you might try to verify if buying a bigger power supply might help. I'd only do it if you have everything in house already....

  • 0 in reply to e14 Contributor

    BTW how big is the drive you are trying to get to work?  Maybe a 3.5" drive might not be able to get the required power (sometimes over 1.5A).