[SOLVED] Powered USB hub, use only the data lines

[palu3492]

My setup:

• Powered USB hub
• Wall outlet power adapter plugged into the hub
• USB devices plugged into the hub
• Hub USB cord plugged into my computer

Since my USB hub is getting auxiliary power, could I cut the hot wire on the USB cord leading to my computer so that I'm only using the data lines for communication with my USB devices?
Would this work or is the hot wire leading from the hub to my computer necessary for data communication even though it's not providing power to my USB devices?

Thanks.

 

[ex_bubblehead]

And the question is. Why, exactly, do you want to do this? What do you hope to achieve by making this modification? Please be specific.

 

[USAFRet]

I'm also going to ask....Why?

 

[palu3492]

Ah yes, I suppose an explanation would help.

I'm working with a Raspberry Pi and using a relay to turn on and off a USB hub that has a cellular modem connected to it. I'm turning the hub on and off to conserve the battery, which is the power source. The problem is, turning the hub on while the Pi is running will reboot the Pi due to the increase in the current draw. I was thinking that I could use a powered hub and power my modem via that rather than powering it via the Pi. However, putting the relay on just the powered hub's auxiliary power input would still allow the Pi to power the hub when the relay is off. So my idea was to cut the hot wire to the hub from the Pi so that the Pi won't power the hub while the relay is off.

Leaving the question of will the hub still work with the hot wire cut?

 

[palu3492]

Tested this. It does work. Powering the USB devices via the hub with a power supply and doing data communication over a USB cable with a cut hot wire works.

 

[USAFRet]

Tested this. It does work. Powering the USB devices via the hub with a power supply and doing data communication over a USB cable with a cut hot wire works.

And this is dependent on the specific USB hub involved.
Some are better than others.

Doing this with some of them may result in dead components.