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Is it possible to power a USB Hub by plugging into one of the ports in the hub a USB Male to male cable, and the end plugged in another USB port of PC? Will the hub draw power this way?

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To clarify, will the hub draw power from the other PC port and distribute the power among the different ports in the hub? –  who manchu May 30 '13 at 21:24

2 Answers 2

No, That's not how USB hubs work. They are designed to pull power from the USB you plug into that came with the hub or from an alternate power source.

The wiring is done so that everything is technically wired to that 1 outgoing connection to the PC.

If you want the pinout of the USB wire see this site. (VCC is power)

The USB Pinout:
Pin  Name    Cable color     Description
1    VCC     Red             +5 VDC
2    D-      White           Data -
3    D+      Green           Data +
4    GND     Black           Ground
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ah but maybe if he can "split" the hard wired usb wire, I mean convert it into 2 sockets, then he could power the hub from 2 computers. –  barlop May 30 '13 at 21:45
    
I guess if he REALLY REALLY wanted to... –  Will.Beninger May 30 '13 at 21:48
    
Is there anything like a "USB 3.0 Y (dual male A) to female A cable"? Can't seem to find it anywhere.. –  who manchu May 30 '13 at 22:02
    
Ya I really don't think so... Any time I see dual male USB cords it's for things like an external hard drive or something that needs more power –  Will.Beninger May 30 '13 at 23:17
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Found exactly what I was looking for. Theoretically it should be able to provide up to 1000mA to the all of the ports in the hub combined. http://amazon.com/gp/product/B007VUF1HY/ Hopefully it will provide atleast 500mA to one port (USB 3.0 portable hard drive <-> file transfers between multiple USB 3.0 sticks, all connected to the same hub) –  who manchu May 31 '13 at 0:35

I'm not sure about now, but few years ago it was common that USB controllers provided 300 mA (or 500 mA) of current for each pair of USB ports to share. It wasn't necessarily split equally, if you had one device that needed 50 mA and second one that needed 250 mA, they'd both work.

Let's assume that nowadays each port has guaranteed current of 300 mA. This isn't necessarily true, but it's the more optimistic option.

When you connect a (for example) 4-port hub, then you have 300 mA of current to split between 4 ports plus for the hub itself, as it consumeed some power too. That's about 60-70 mA per device, surely not sufficient for external hard drives just to give an example.

Theoretically you could power that hub from another port (or another controller, or even another PC), but it won't be much better: you'll have 600 mA to split between 4 ports. To be sure that every port gets its 300 mA you'd have to draw power from 4 ports, but your hub is connected to the fifth one and has only 4 ports, so it doesn't make much sense.

The entire thing about powered hubs is that they draw external power to boost your controller's ports.

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