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I am building a movement monitoring system on a Raspberry Pi 2. I've just put a meter on the 5V and GND pins, and I'm measuring ~10V. The 3V3 and GND show 7.5V.

What on earth is going on? Or have I got this wrong somehow?

BTW - Windows 10 IoT is running OK on the Pi.

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    If those voltages hit any of those pins, your Pi would likely release the magic smoke. If it hasn't, there's something amiss with your metering arrangement. – goobering Feb 10 '16 at 10:08
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    What are you using to measure the voltage with, a standard multimeter? It could one of many reasons that you are getting twice the expected reading. As a sanity check - maybe your meter badly needs calibrating (do you have a reference with which to check it?), or the input impedance of the meter is too low (see Why does an oscilloscope show a different voltage from a signal generator?), or you have the leads plugged in to the current measuring socket? – Greenonline Feb 10 '16 at 10:23
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    Your meter needs a new battery, or you have killed the Pi. What is the rating of your power supply? – joan Feb 10 '16 at 10:31
  • Ah - a 9V battery is reading as 11.7V. My meter seems chuffed. – Phil Wilson Feb 10 '16 at 13:49
  • The leads are in the correct sockets, and it's on the correct setting - but it seems far from correct. That will teach me just to trust it blindly. Thank you all. – Phil Wilson Feb 10 '16 at 13:50
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A new battery in the multimeter has fixed the problem. I never knew a low battery would affect it's readings - I assumed if it switched on, it was good to go.

With the new battery it's reading 8.7V for a fresh 9V battery. Still not super-accurate (time for a new one I think), but at least it shows my Pi is OK.

Thanks for the help everyone. (I would mark someone's answer as correct, but they are all comments.)

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