Mar 012017
 
Pi Power Usage chart adding Zero W

It’s become traditional for me to do power measurements of any new Pi and update my chart. People have even started asking me about it on launch days (the cheek of it)…

Needless to say I have done some power measurements in my Zero W testing and here are the results. Essentially, the Pi Zero W seems to require 20 mA more than the no-wifi Zero. This is almost certainly due to the new radio chip.

Methodology

Measurements were taken using my standard procedure (same as for the last several Pi models launched). Current and voltage are measured using my eMeter with a calibrated 20 Amp shunt whilst performing four different activities. “Shooting video” is done without saving the video output to the SD card. Watching video is done with a 1080p video on the SD card. The rest is self-explanatory. The camera module is unplugged for all but the shooting video test. Only HDMI and a USB keyboard dongle were plugged in. The Pi Zero W was connected to wifi, but no bluetooth devices were in use.

Pi Power Usage table adding Zero W

Pi Power Usage table adding Zero W (at 5.19V)

Why Anomolous?

No doubt you will wonder why the shooting video figure is anomolously lower on the Zero W. I do too. But it could be experimental error – we are pushing the limits of the eMeter’s resolution here. These figures are just a guide. If you need something really accurate, you’ll need to buy expensive gear and do some measurements. But my measurements usually line up pretty well with the official figures and those of people like Dave Akerman who DO have fancy-pants meters by the likes of Fluke. So, if you need a guide to work out your probable battery duration, these are fine, but if you’re going to use the figures for something that really matters, well, don’t! Here’s the chart…

Pi Power Usage chart adding Zero W

Pi Power Usage chart adding Zero W (at 5.19V)

So I hope these figures are a useful guide, but don’t bet your life on them please.

  15 Responses to “How much power does Pi Zero W use?”

  1. How about testing g the WiFi, comparing the zero + dongle with the W?

  2. Alex Results for the video capture could it be that you made the Zero+ V1 camera and now used Zero W + V2 camera.
    TerryR

    • Yes. Good point. It could be. That had occurred to me and one day I might rerun the tests. :)
      But it won’t be this week as I have all sorts of stuff to do for tomorrow and the week-end.

  3. Only a suggestion, but have you tested the ‘new’ Pi2B with the BCM2837, to see if it behaves any differently power-wise to the Pi2B with BCM2836?

    Thanks for the figures above, really interesting to see how minimal the WiFi power-consumption is. Might also be interesting to see if the WiFi power-consumption varies between the Wifi being ‘connected but idle’ and ‘connected and actively streaming’?

  4. what’s this in watts, so i can estimate my electric bill if i leave it on all year round?

    • All the measurements were at 5.19V and are listed in milliAmps

      Watts is Volts x Amps

      So multiply 5.19V * milliAmps / 1000 and you get Watts

    • Watts = Voltage x Current, so in raw terms the Pi Zero W at idle will use 0.6W
      However that ignores any power-loss in the PSU converting from mains electricity to the 5V needed by the Pi Zero W. Assuming 80% efficiency, that’s still only 0.75 Watts – which works out as 6.5kWh for a whole year, which would cost you roughly 80pence for a whole year in the UK. I don’t think it’s going to break the bank ;-)

  5. Nice information. Now we have the Rpi Zero W which is “out of stock” instead of the Rpi Zero, which is “out of stock”.

  6. Should the Pi2B and Pi3B really be identical? e.g. compare to the data at https://www.raspberrypi.org/help/faqs/#powerReqs

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