TheJH
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Re: Power Consumption: Some numbers?

Fri Feb 17, 2012 10:15 pm

Hello,

as I already read that the board will only use 5V and less than 1A, it seems clear to me that more than 5W will never be necessary. However, I'd like to know more exactly what power consumption will be like - for example, I assume that it will be much lower when the device is idling, no X server is active, the USB ports are shut down, no audio playback is running and there's only an active LAN connection. Can someone tell me how high it will roughly be?

zog
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Re: Power Consumption: Some numbers?

Sat Feb 18, 2012 5:35 am

Hi please could I add some enviromental testing stats would be good too, I envisage putting these devices outside, I want to know how hot I can bake and how cold I make them before they pack up. Also emf testing might be a good idea.

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oztrailrider
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Re: Power Consumption: Some numbers?

Sat Feb 18, 2012 8:02 am

I know one of the beta boards was tested averaging around 3.5W when displaying a desktop. Have a search through the forum here. I don't know whether there are any more concrete numbers around at this stage.

a10112
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Re: Power Consumption: Some numbers?

Sat Feb 18, 2012 8:39 am

I was wondering if the RPi could be used with a Y-split USB cable for more amperage. I know USB-powered HDDs and external CD/DVD/BD drives use these Y-split USB cables for around 2A total.

sidtupper
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Re: Power Consumption: Some numbers?

Tue Apr 17, 2012 9:51 pm

I hope that soon someone will report power consumption numbers.  I'd like to know what a headless Raspberry Pi B uses idling, ie, no keyboard, mouse, display, desktop.  A few bytes of data come in a USB port every 5 minutes.  1 watt would be very nice for my purposes.

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mahjongg
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Re: Power Consumption: Some numbers?

Tue Apr 17, 2012 10:06 pm

a10112 said:


I was wondering if the RPi could be used with a Y-split USB cable for more amperage. I know USB-powered HDDs and external CD/DVD/BD drives use these Y-split USB cables for around 2A total.


Yes, people have reported success with such a cable.

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cakiwi
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Re: Power Consumption: Some numbers?

Wed Apr 18, 2012 12:50 am

There are some power consumption numbers in a post in this thread

http://www.raspberrypi.org/for.....-pi-owners

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jbeale
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Re: Power Consumption: Some numbers?

Wed Apr 18, 2012 1:29 am

sidtupper said:


I hope that soon someone will report power consumption numbers.  I'd like to know what a headless Raspberry Pi B uses idling, ie, no keyboard, mouse, display, desktop.  A few bytes of data come in a USB port every 5 minutes.  1 watt would be very nice for my purposes.


I've seen 350 mA at 5V reported, which would be 1.75 watts. Ethernet interfaces usually draw significant current so if you aren't using that, and could turn it off, there ought to be some savings there. Not sure if the capability exists to turn off the ethernet hardware though (note the USB ports connect through that chip also).  Likewise, haven't seen anything about ability to power down the GPU. If Broadcom designed the SoC to be used in a media player like Roku2, they probably wouldn't imagine anyone wanting to use it without the GPU running.

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Jim Manley
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Re: Power Consumption: Some numbers?

Wed Apr 18, 2012 4:21 am

It's been posted elsewhere that the bare Pi uses about 330 ma when idling and with nothing else connected other than HDMI (which draws no current, so all further examples include HDMI).  With a keyboard, mouse, and network connected the current draw of the Pi is about 385 ma, and with keyboard, mouse, and network connected and the ARM CPU running at about 99% of load, the Pi draws about 450 ~ 550 ma.  That leaves up to 250 ma for various levels of GPU load and/or additional minimal-load USB devices before hitting the 700 ma maximum that the on-board components and printed-circuit board traces can carry.

The BRCM2835 SoC used in the Pi (same as the Roku 2 models) automagically performs GPU power management dynamically based on usage and, although it can be overridden in the /boot/config.txt file, it then runs full-bore no matter how much, or little, computation is being done on the GPU.
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