Nov 122014
Raspberry Pi A+ power measurements

Two Raspberry Pi A+ arrived from Farnell yesterday, so I spent the afternoon doing some power measurements. I also made a comparison video showing power measurements for an A+, a B+ and an old model A Pi.

As before, when I did a similar thing for the B+, I used my trusty eMeter. But this time I used it inline with an ISO-TECH IPS 3303D bench power supply (at 5.2V) to corroborate the readings.


I wanted to see how much current each Pi would consume under four circumstances….

  1. Idling in command line – low CPU load
  2. Starting LXDE desktop – heavy CPU load
  3. Watching Big Buck Bunny in HD – GPU load
  4. Filming Full HD video with Pi camera – GPU load + camera load

So this was done for each Pi in turn, A+, then B+, then A. I didn’t bother with the B as we had a separate B+/B comparison when B+ was launched. (I did the B rev 2 without filming the next day and updated the table.) All measurements were using a bench-supply set to a regulated 5.2V.

Video Of The Testing

Here’s a video of the testing. I used two cameras to get a close-up view of the meter readings. (Always try new things.)

What About The Results?

Power Measurements for Raspbery Pi A+, A, B+, B (rev 2)

Power Measurements for Raspbery Pi A+, A, B+, B (rev 2)

Clive Beale made a graph of the results which, obviously, I wish I’d thought of doing. It shows the comparison very nicely…

Idling CLI (0.52 W)

Idling in the command line, the A+ uses 100 mA, which is 40 mA less than the A, half the current draw of the B+ and a bit over a quarter of the original model B (360 mA).

Idling, the A+ uses 71% of the power of the model A.

CPU Load (0.68 W)

Loading LXDE, the A+ uses 68% of the power of the model A.

GPU Load (0.73 W)

Under GPU load, the A+ uses 70% of the power of the model A.

GPU Load + Camera (1.2 W)

Under GPU + camera load, the A+ uses 72% of the power of the model A.

Obviously these figures are subject to a small amount of experimental error, but I think we can safely say that the A+ uses about 70% of the power of a model A. That’s a very useful improvement. Brilliant for battery powered applications.

Depending on what you’re doing, the A+ uses between 50% and 70% of the power used by a B+ (the camera adds 100 mA to both, which affects the A+ proportionately more in % terms).

  32 Responses to “Raspberry Pi A+ How Much Power Does It Need?”

  1. Brilliant! This shows that the A+ is a very welcome member to the family!

  2. That also implies why the camera pictures can appear unstable (flickering) in preview mode on older Model B.

  3. […] of you who don’t want to watch the entire video, he’s also provided a summary table. Read more and watch the video here. It really shows the low power consumption of the A+, which makes it ideal for battery-powered and […]

  4. Brilliant video! Thanks for taking the time to do such detailed testing (& editing) Alex :-)
    Just for the sake of easier-comparisons, could you add your earlier Model-B test results to your table above?

    Having a full Linux system with HDMI output, idling at just half a Watt is incredible, well done RPF :)
    Any idea if the current would decrease even further if you disconnected the keyboard dongle and switched off the HDMI output with ‘tvservice -o’? (you can use a TTL-UART cable to control the Pi over the serial port, if you have one)

    If you find the time, it would be great to see a similar power-consumption-test video for the HDMIPi itself, both with and without the HDMIPi powering an attached Pi, with and without the display switched on (via the ‘POWER’ button) and with and without any HDMI signal actually attached. (i.e. so we get the full range of maximum-possible and minimum-possible power usage figures)

    • Thanks Andrew.

      In an ideal world I would have tested a model B then and there along with the others, so that everything would have been totally comparable, done on the same day with the same equipment (I even used the same micro SD card for all measurements). But it took about half an hour for each set, plus setup time, plus the complications of running two cameras etc. After 3 I’d had enough. I figured why bother with the model B since we have a B/B+ comparison.

      I didn’t put the B in the table because it was measured using different power source, which sagged to a lower voltage, hence not directly comparable (although you could compare the Watts, I suppose). PLus I didn’t use the same testing scheme for the model B.

      B: 4.98 V, 0.38 A, 1.89 Watts
      B+: 5.03 V, 0.24 A, 1.21 Watts

      I could, however do some after the fact model B tests, perhaps tomorrow, for the sake of completeness :)

      Love the idea about the HDMIPi tests too. Will do that at some point. Actually, I was in the garage measuring A+ with HDMIPi while you wrote that comment, but just a quick and dirty. 5.14V, 1.1A idle, 5.14V 1.12-1.14A GPU use.

    • Model B results measured and added. That’s for rev 2. If you ask me for rev. 1 I’ll swear ;p

  5. Interesting test, but would you care to detail what PS you used?

  6. Excuse me , I wanna know where can I buy the LCD which you use in the video ?
    I find so many place , but I can’t find the same type.

  7. Hi! I just got an A+ model and I’m looking for schematics and GPIO details. Do you know where I can find this?
    Thank you !

  8. Thanks a lot for the testing, which is very informative.

  9. This article could do with an update to include the Pi 2 B and the PiZero ;-)


    • I suggest you look at the one I published yesterday

      • Alex – I agree with your reply, but for future reference maybe it’d be useful to update the article here (which possibly has quite a few incoming links / bookmarks?) to include a link to the most recent ‘update’ on this subject?

        • You’re probably right (you usually are) :P but people have to remember this is a blog and the zero was released 3 days ago, so why comment on a page that’s a year old and entitled A+? There was also an update for pi2 a day or two after it came out.

  10. My Raspberry A+ with a usb to ethernet works as webserver, printserver “with samba so i have a little workgroup filesystem”, and a veryyyyyyy light ftp server, this machine does a beautiful job “the site does not have that many clicks so the workload is minimal” I only have it connected to power and ethernet and the machine works as a charm, now testing it’s uptime.

Leave a Reply