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Interesting Power Over Usb


xiolo
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Got a 5V powered usb so that I could have both a 4gb usb storage and a tethered android phone at the same time...

And to my surprise, plugging the usb hub into the pineapple powers the pineapple as well !!! So no need for external power to the pineapple while a main/battery powered usb hub is plugged in.

Is it expected behavior, i.e the pineapple getting its juice from its usb port ? [and is it safe?]

I tried it with a another usb main powered hub, and similar behavior, so it was not just the first usb hub misbehaving.

thanks for your help

K

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Your hub must be back-feeding the usb host (mk IV). What model is this? without a limiting circuit in the hub IF you plugged the wrong power adapter in (polarity) You might fry the usb port that is acting as the host.

My hub does not do this (just checked) But I guess it makes sense if the 5v is being powered out the USB port on the Mk IV and depending on the location of the voltage regulator to the rest of the Mk IV it would be possible to feed the MK IV via USB Host.

Once Again Be Careful as it could damage the MK IV to have -5v or a higher voltage (-+6v out of USB spec) back-fed into the Mk IV.

What Model HUB are you using?

I'm using a DyNEX 4 Port Travel Hub DX-THUB16

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and having the pineapple draw power/amperage could damage it because the usb part may not be designed for that much current.

kinda like when installing an amp into a car you need to do the math to figure out what is a safe gauge of wire, if you choose a higher gauge like 18(small wire) then it could turn into a heating element :-p

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  • 2 weeks later...

Warning !

The usb port can only handle 500 mAh, and the MK4 slurps at least 1000 mAh, it's only a matter of time for it to get fried, so keep powering it thru USB port then you will be looking to buy another MK4.

When using the hakshop usb spyder, always power everything at the same time so you would not give it a chance to load up on the USB side.

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Darren first realized this soon after the mark4 was released (theres a post somewhere around here about it...). The way around it is to modify the usb cable that goes from the pineapple to the hub. Simply snip the red and black wires, that way only data is transferred between the pineapple and hub, and only devices connected to the hub (3g dongle, alfa wifi card, etc) get the power. I did the same thing with my raspberry pi to protect it, as just like the mark4, theres no fuse.

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