[colug-432] RPi peripheral power consumption

[Vince Herried]

PI power.  I had a lot of problems with  my pi wifi.
I found the problem to be caused by a six foot long usb power cable.
Replaced it with a 3 foot one and my problems went away.

Measure the  voltage on,  I think it was tp1.
I was way below recommendations.

I'm still having erratic drops in wifi.
This morning I noticed it was down,  re-plugging the wifi dongle fixed it,
apparently it had  rebooted.
The uptime once I got around to checking was only 42 minutes.

I just finished writing a  script to check network availability and if it
drops, re-boot.

I should hook up my kilowatt to it and see what the usb wall wart is
drawing.

---------
Vince



On Sat, May 18, 2013 at 11:39 AM, <jep200404 at columbus.rr.com> wrote:

> On Sat, 18 May 2013 09:59:46 -0400, Scott Merrill <skippy at skippy.net>
> wrote:
>
> > Can someone tell me - in general - which would draw more power on a
> > Raspberry Pi: a USB WiFi adapter or the onboard Ethernet port?
>
> That depends on the USB Wifi adapter. I have an old one that I
> think pulls around 450 mA. That's much for any USB thing,
> and much more than the ethernet port uses.
> However, for newer Wifi adapters, althought I just don't _know_
> how much power they use, it's likely to be much less than my
> old Wifi adapter.
>
> Look at the output of lsusb to see the claimed max power for
> each USB thing you try. IIRC, the Pi's ethernet port is a USB
> device.
>
> I guess in your case the power supply comparison would be
> USB Wifi versus _incremental_ power used by ethernet port
> when something is plugged into it and schlepping bits back
> and forth.
>
> > Or is the power draw differential so inconsequential as to not be worth
> > worrying about?
>
> That depends on what your power concerns are. If you are running
> on batteries, it can be a big big concern. My Pi was flaky because
> the wall wart I was using just was not powerful enough. After I
> started using a more powerful wall wart, it became reliable.
> In some other applications, heat can be a concern.
>
> Besides curiosity, what power concerns do you have?
>
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