groudon
Posts: 1
Joined: Tue Apr 09, 2019 6:19 am

Power the Pi from external harddrive "charge port"

Tue Apr 09, 2019 6:32 am

Hello, newb here asking a newb question,

I just purchased an external HDD, which has 2 USB ports (for "charging your devices"). I plug the Pi power cable into one of these ports, and the Pi turns on and runs great.

But then if I connect the HDD data cable to the USB port on the Pi, the Pi shuts right off. It won't turn on again until I unplug the data USB.

Has anyone been tried to make this work? Is there any risk to running off the HDD power?

Thanks for any assist!
HDD power.jpg
HDD power.jpg (95.42 KiB) Viewed 781 times

fruitoftheloom
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Re: Power the Pi from external harddrive "charge port"

Tue Apr 09, 2019 10:07 am

groudon wrote:
Tue Apr 09, 2019 6:32 am
Hello, newb here asking a newb question,

I just purchased an external HDD, which has 2 USB ports (for "charging your devices"). I plug the Pi power cable into one of these ports, and the Pi turns on and runs great.

But then if I connect the HDD data cable to the USB port on the Pi, the Pi shuts right off. It won't turn on again until I unplug the data USB.

Has anyone been tried to make this work? Is there any risk to running off the HDD power?

Thanks for any assist!

HDD power.jpg

A phone charger will not give stable power which is required by the Raspberry Pi SBC.

Just use the Official Power Supply to power the RPi..
adieu

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PhatFil
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Re: Power the Pi from external harddrive "charge port"

Tue Apr 09, 2019 10:31 am

can you link to a spec listing for your hdd enclosure with phone charging ports? If the enclosure also has a network port i would suspect that they are simply client device (2nd hdd/printer) ports..

If the enclosure has a suitable psu to power both hdd and your pi, you could try a literal hack of the usb data cable and try cutting the +5v line and perhaps the ground too but there are a lot of IFS along the test track..

LTolledo
Posts: 1371
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Re: Power the Pi from external harddrive "charge port"

Tue Apr 09, 2019 9:23 pm

Your RPi already showed you that it cant

repeating the process can potentially damage your RPi and /or HDD.

save yourself the all the frustration and get a proper power supply for your RPi.
(is a $9 RPF-power supply more expensive than damaging your $35 RPi and/or $100 HDD?)
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HawaiianPi
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Re: Power the Pi from external harddrive "charge port"

Tue Apr 09, 2019 10:15 pm

groudon wrote:
Tue Apr 09, 2019 6:32 am
But then if I connect the HDD data cable to the USB port on the Pi, the Pi shuts right off. It won't turn on again until I unplug the data USB.

Has anyone been tried to make this work? Is there any risk to running off the HDD power?
It's unlikely the charging ports are designed to deliver up to 2.5A, which is the recommended power spec for Pi3 computers. And even if they were, chargers are not power supplies and often won't maintain a stable 5V under load. Batteries don't care if the voltage droops while charging (most phones only need a little over 4.2V to charge), and generally ignore things like ripple or noise. Computers need a proper power supply.

Click the green BUY tag at the top of the page and look for the official Raspberry Pi Universal Power Supply.
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