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Measuring Low Power Usage Over Time

Discussion in 'General Electronics Discussion' started by acawley, Jun 21, 2017.

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  1. acawley

    acawley

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    Jun 21, 2017
    I'm new - first post here so please go easy!

    I intend to build a project (a off-grid Owl Nest-box camera) using a Raspberry Pi (I have 6 different models some of which are the low-power "Zero"). I am trying to calculate power usage over time to calculate battery requirements. I'm trying to determine what would be a good (hopefully low-cost) device for measuring power consumption of different Pi's over time.

    I recently purchased a MUKER-TM103 - https://www.amazon.co.uk/MUKER-TM10...F8&qid=1497805163&sr=8-1&keywords=MUKER-TM103
    Which allows you to measure voltage, current / A or mAH and displays the time passed in the top right corner of the screen. On the face of it this item looked perfect for my needs.

    First impressions were great, plugged in my phone and it did its job as advertised. However as soon as I started using it with really low-powered devices like the Raspberry Pi A+ or Pi Zero it shows the Amps as 0.02-0.12 which was expected but frustratingly it fails to start the timer or mAH count, rendering it useless for my purposes. If you plug in something that demands a little more current from it the counters start. I realise that it may just be that this piece of equipment may just be too cheap and not sensitive enough for my purposes, so my question would be what would be the correct piece of equipment to measure mAH of low powered devices over time via USB? And can this be done with a relatively low-budget piece of kit.

    I have a digital multi meter so I suppose I could butcher a USB cable to take a in-line current reading, I've never done this but I think I know how, however although that would give me a at the moment reading, I don't know how I could accurately measure the overall usage over an allotted time using that method, because it will vary and spike.

    Any suggestions or advice to an electronic n00bie would be gratefully received.

    Thanks for your time and help.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,401
    2,777
    Jan 21, 2010
    There are multimeters with logging functions, and also some with an isolated issue interface.

    Either can be used to get an idea of what is happening over time
     
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