Confusing about back powering issue with Pi zero w #279

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opened 2026-02-20 13:23:51 -05:00 by deekerman · 5 comments

deekerman commented

2026-02-20 13:23:51 -05:00

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Originally created by @SachiaLanlus on GitHub (Jun 20, 2021).

Originally assigned to: @mdevaev on GitHub.

As the conclusion in both the #225 and #11 ,
that 2 power source at the same time is definitely not a good idea.
However, Novaspirit Tech mentioned that because pi zero is a underpowered device, it is able to be powered through the same port that plugged into the pc.
I just wondering that if I would like to use pi zero w to build the pi-kvm,
can I only plug 1 port to pc and left another empty?
Except for under power issue, is there any issue I should notice or worry about in this scenario?
Thank you

Originally created by @SachiaLanlus on GitHub (Jun 20, 2021). Originally assigned to: @mdevaev on GitHub. As the conclusion in both the #225 and #11 , that 2 power source at the same time is definitely not a good idea. However, [Novaspirit Tech](https://www.youtube.com/watch?v=xCL5AS0t5Is&t=69s) mentioned that because pi zero is a underpowered device, it is able to be powered through the same port that plugged into the pc. I just wondering that if I would like to use pi zero w to build the pi-kvm, can I only plug 1 port to pc and left another empty? Except for under power issue, is there any issue I should notice or worry about in this scenario? Thank you

deekerman

2026-02-20 13:23:51 -05:00

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deekerman commented

2026-02-20 13:23:53 -05:00

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@wnark commented on GitHub (Jun 24, 2021):

If your computer is a regular brand, the current of USB2.0 is sufficient for Raspberry Pi Zero. It has been measured with a USB ammeter, high load only needs 100-200ma current

@wnark commented on GitHub (Jun 24, 2021): If your computer is a regular brand, the current of USB2.0 is sufficient for Raspberry Pi Zero. It has been measured with a USB ammeter, high load only needs 100-200ma current

deekerman commented

2026-02-20 13:23:53 -05:00

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@mdevaev commented on GitHub (Jun 24, 2021):

This ^

@mdevaev commented on GitHub (Jun 24, 2021): This ^

deekerman commented

2026-02-20 13:23:53 -05:00

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@SachiaLanlus commented on GitHub (Jun 25, 2021):

In my test, the maximum total system power draw is 410mA.
At that time, the cpu utilization is 90~100%.
And it works well now.
Thank you

But I just notice another issue, that sometime the HID will not work.
And just a reboot can fix it.
So when I reboot the pikvm, I should check whether HID work or not.
It just a minor issue, so it is fine for me.

@SachiaLanlus commented on GitHub (Jun 25, 2021): In my test, the maximum total system power draw is 410mA. At that time, the cpu utilization is 90~100%. And it works well now. Thank you But I just notice another issue, that sometime the HID will not work. And just a reboot can fix it. So when I reboot the pikvm, I should check whether HID work or not. It just a minor issue, so it is fine for me.

deekerman commented

2026-02-20 13:23:53 -05:00

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@wnark commented on GitHub (Jun 25, 2021):

In my test, the maximum total system power draw is 410mA.
At that time, the cpu utilization is 90~100%.
And it works well now.
Thank you

But I just notice another issue, that sometime the HID will not work.
And just a reboot can fix it.
So when I reboot the pikvm, I should check whether HID work or not.
It just a minor issue, so it is fine for me.

It may be related to the power consumption of the external device used，Not much difference haha

@wnark commented on GitHub (Jun 25, 2021): > In my test, the maximum total system power draw is 410mA. > At that time, the cpu utilization is 90~100%. > And it works well now. > Thank you > > But I just notice another issue, that sometime the HID will not work. > And just a reboot can fix it. > So when I reboot the pikvm, I should check whether HID work or not. > It just a minor issue, so it is fine for me. ![1624607101422](https://user-images.githubusercontent.com/24355466/123389460-7b15c100-d5cc-11eb-9516-ae852c8b7550.jpg) It may be related to the power consumption of the external device used，Not much difference haha

deekerman commented

2026-02-20 13:23:53 -05:00

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@SachiaLanlus commented on GitHub (Jun 25, 2021):

In my test, the maximum total system power draw is 410mA.
At that time, the cpu utilization is 90~100%.
And it works well now.
Thank you
But I just notice another issue, that sometime the HID will not work.
And just a reboot can fix it.
So when I reboot the pikvm, I should check whether HID work or not.
It just a minor issue, so it is fine for me.

It may be related to the power consumption of the external device used，Not much difference haha

Thank you for sharing your experience!
I try to measure again, and the average power consumption is just like yours.

@SachiaLanlus commented on GitHub (Jun 25, 2021): > > In my test, the maximum total system power draw is 410mA. > > At that time, the cpu utilization is 90~100%. > > And it works well now. > > Thank you > > But I just notice another issue, that sometime the HID will not work. > > And just a reboot can fix it. > > So when I reboot the pikvm, I should check whether HID work or not. > > It just a minor issue, so it is fine for me. > > ![1624607101422](https://user-images.githubusercontent.com/24355466/123389460-7b15c100-d5cc-11eb-9516-ae852c8b7550.jpg) > It may be related to the power consumption of the external device used，Not much difference haha Thank you for sharing your experience! I try to measure again, and the average power consumption is just like yours.