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  • What's the current draw when the Raspi is at idle (min), and at 100% CPU/GPU (max)?
    (With no peripherals/accessories plugged in)

  • What's the minimum and maximum voltage allowed to run the Raspi stably?

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1  
I'll get my power supply & oscilloscope out after exams, but until then there's a forum post with some benchmarks: raspberrypi.org/phpBB3/viewtopic.php?f=2&t=6050 – Alex L Jun 15 '12 at 10:02
The foundation's page on power supply: raspberrypi.org/archives/260 – Alex L Jun 15 '12 at 10:08
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+1 Great question. – Jivings♦ Jun 15 '12 at 10:23
@Alex If you're going to link to the answer in your comments, why not create a canonical post here? – Robert Cartaino♦ Jun 15 '12 at 19:33
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@RobertCartaino I will do, after exams! – Alex L Jun 15 '12 at 20:06
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4 Answers

up vote 4 down vote accepted

Look at:

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=6050&start=50

It shows that power drainage is variable, depending of the connected devices. Tests never reached 700 mA. Max was 515 mA.

I reordered the metrics in the source article by mA drainage:

  • 322mA at 5.09V - at login prompt on Arch, idle CPU, nothing plugged but power (1.64 Watt).
  • 322mA ~ 323mA - only power, no IO, (peaks at 350-390mA when CPU solicited).
  • 335mA - only a couple PS2 keyboard & optical mouse plugged together on one USB port with an adapter (+30mA when mouse in use, +7mA when num lock LED on!)
  • 375mA - ethernet only.
  • 377mA - ethernet and composite video (compared to 375mA without video composite).
  • 386mA - Mouse&KB + ethernet and idle CPU.
  • 389mA - Mouse&KB + composite video + ethernet at idle CPU.
  • 394mA - CPU idle, LXDE/X11 on!, composite video, ethernet, PS2 KB&Mouse together on one USB port.
  • 435mA ~ 465mA - ethernet only, CPU stress test with ethernet only with 'stress --cpu 8 --io 4 --vm 2 --vm-bytes 4M --timeout 20s'.
  • 440mA (peaks @ 480mA) - Mouse&KB + composite video + ethernet with CPU stress.
  • 475mA ~ 515mA - LXDE/X11 on!, composite video, ethernet, PS2 KB&Mouse together on one USB port, mouse in use + CPU stress, LXDE/X11 on.

Mouse & KB: draw 28mA when idle, to 80mA when mouse in use + 7 to 8mA per keyboard LED when on.

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Hi there! Although you can leave it as a reference, try and sumarise the information in your link as best you can in your answer. This helps to prevent the information being lost if the link ever changes. Thanks! – Jivings♦ Jul 21 '12 at 13:25
up vote 3 down vote

The model B requires 700 mA at 5 V. That's the maximum for the overall board. The A is 300 mA. USB is +/- 5% so 4.75-5.25 V. Since this includes 2 x USB; the board itself is 500 mA.

While USB can be up to 500 mA, a device must request that; otherwise it gets the default 100 mA.

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Why the downvotes? – Brian Carlton Jul 18 '12 at 16:54
idk, accurate answer – XAleXOwnZX Jul 21 '12 at 2:50
Because it's variable with usage, not constant at 700mA. 700 takes into account 100 for each USB port, and is a maximum safe value. The answer shows no understanding of electronics and is already common knowledge – Alex L Jul 21 '12 at 11:08
up vote 2 down vote

The RPi Performance wiki page has some sample readings:

  • Booting: 120-400mA (that's 0.6-2W)
  • Idling: 320mA without network, 370mA with (that's 1.6-1.85W)
  • 1080p video playback: 750mA (that's 3.75W)

With the exception of 1080p playback, I took the measurements myself with a lab power supply, so I can verify their accuracy. No USB devices (keyboard/mouse) were connected. Neither was HDMI, but I suspect the HDMI output was still running.

Interestingly my PS/2 keyboard (connected via a USB adapter) was rated at 75mA but only increased the power draw by 10mA.

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up vote -1 down vote

Current:

The model A and B require 300 mA and 700 mA (respectively) maximum for the board on it's own.

Voltage:

The board requires USB power, which is 5v ± 5% - 4.75-5.25 V.

  • The RPi has limited voltage regulation so do not go outside this threshold!
  • Many power supplies advertised for the RPi are actually 5.25v, so that the voltage drop endured during use will balance out with the higher voltage to produce the desired 5v
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