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I want to use my raspberry pi 2 as an media center and use movies from my usb HDD Now the problem is that it runs short on power for that usb HDD (my usb hdd uses 2 usb ports btw)

Now I found an old usb hub with external power supply (5v, 2A) and I have a small box where I can fit both the usb hub and the Pi in, to keep everything clean I want to make those 2 power cables into 1, this ain't that hard but now the problem:

The hdmi port is on thesame side as the power in port, so my question is can I give power to it without having to access this port? Will this have any cons/pros and how can I do this?

goldilocks
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roy Steen
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  • Before you go with hub for the HDD, try this. It should allow you to run it directly off a Pi 2 with a decent 2+ A supply. The reason it will not work otherwise is two USB jacks would be expected to provide > 600 mA. – goldilocks Oct 28 '15 at 17:01
  • The problem is that I get the little rainbow on the right top of my screen so it means that the pi then doesn't get enough power, so that won't work? – roy Steen Oct 28 '15 at 17:29
  • It may mean you need a better power supply, but the only way to tell would be to try one. Officially, with max_usb_current=1, there should be 1200 mA available to the USB ports, and technically, a conforming USB device should not expect more than 500 mA per port. However, officially without it set there should still be 600 mA, which should be enough for one port, but my HDD (which only uses one port) definitely won't work that way, whereas using the same 2.5 A supply with max_current set it does. – goldilocks Oct 28 '15 at 17:42
  • So either the Foundation's numbers are exaggerated, or the drive wants an excessive amount of power for one jack. I'd guess the latter, but I'd also think a drive with 2 jacks is a more polite solution (i.e., it wants 500-1000 mA, so within spec). I lot of "maybe, if" in there. I guess it's up to how much faith you have in your current supply (don't bother with < 2 A, and don't count on a hub to deliver that to the pi from one jack) and if not, whether you want to gamble $15-20 for a new one. – goldilocks Oct 28 '15 at 17:42
  • BTW, since it isn't clear in your question which power cables you want to make into one, you can power the pi from the USB hub w/ a USB -> microUSB cable if you are powering the HDD from the hub separately (and the hub is unregulated, which they usually are), which means only one cable into the box (this is what I did before the 2/+ models came along). That doesn't solve your form factor problem, of course. Which I'm glad they moved everything to two sides, it was a mess with stuff sticking out at all angles on the B. – goldilocks Oct 28 '15 at 17:49
  • I only got 1 amp cables tough, the usb hub one is 2 amp (both at 5v) the hub has like a cable that isnt removeable from the plug if you know what i mean – roy Steen Oct 28 '15 at 18:10
  • So If I have an 2 amp power supply I can use 1.2 amps on all 4 usb ports and 0.8 for the rest right? But if I use an 3 amp power supply can I then use 1.2 for usb and 1.8 for the rest or 2.2 for all 4 usbs and 0.8 for the rest? – roy Steen Oct 28 '15 at 20:22
  • I can't say how much you'll be able to use beyond officially it's 1.2 A total from the USB, and the pi itself shouldn't require more than 1. If you know someone with an ipad charger and cable you can use for 5 minutes, you could test this out with that HDD, and whatever else you can find (e.g., a wifi dongle). There's probably not much point going beyond a 2.5 A supply unless you intend to add more stuff via the (unregulated) 5 V pins -- which still is subject to the pi's overall limitations (not sure what it is). I notice you've asked a new question, someone will know the details. – goldilocks Oct 28 '15 at 20:30

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