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I power my RPi3 using a power bank for smartphones, and I'd like to check how much power the Pi draws from it while my project is running.

I don't have any special equipment for power measurement. Is there any way to measure (or at least estimate) how much power is currently drawn from the power bank?

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    You can buy USB in-line power meters e.g. dx.com/p/… – pjc50 Apr 26 '16 at 10:56
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The Pi has no inbuilt current or voltage sensors which could be used for monitoring its own current draw, or a battery supply. You will need to track down a multimeter or other measuring device (this type of thing is very common) to keep track of your power consumption.

  • For stability rather than average power consumption (i.e. how long your battery will last) it would be good to also account for peak power consumption. Digital circuits have a tendency to consume a lot of power in short pulses, and if your supply can't handle it and the voltage buckles too much, you might end up with an unstable system. Measuring peaks requires more intricate tools, but I'm sure somebody has already done research on this and it can be found online. – Matti Virkkunen Apr 26 '16 at 14:35
  • Adding this option for visibility - although the linked item appears to be cheaper, if you want a tool with a wider use-case, you can get a watt meter (such as the Kill A Watt, amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU). You plug it in between the USB charger/power bank and the outlet. It has a wider use-case because you can measure any device that plugs in to an outlet (and not just USB), for slightly more money. – Jake Apr 26 '16 at 18:01
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The Pi 3, while idling, consumes about 220 mA. Under loads, it is known to reach up to 1 A, and with USB devices plugged in, it can reach 2.5 A. There is no on board current sensor, so this is only a tool for a good estimate.

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    Not sure why you received a downvote... Maybe because the answer didn't explicitly state that it's not possible to measure without additional equipment? +1 for giving a good reference for the estimation portion of the question. – Jacobm001 Apr 26 '16 at 1:15

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