I was trying to measure the current draw of a USB-powered device (a Raspberry Pi) to determine the suitability of powering from an external battery pack. So I took a USB cable, split the +5v (red) line, placed a DMM on the line, plugged it in, and got.... nothing. The pi wouldn't boot. Replacing the DMM with a jumper worked fine, so the cable was good and I didn't screw it up with splitting the +5v line. Is it possible the internal resistance of the multimeter caused too much voltage drop on the line for the Pi to boot? What's the right way to do this?
To clear up other possibilities:
- The meter works fine on other applications.
- I double checked the setting of the meter, set to mA.