I just came across an interesting “real world” example of multimeter burden voltage. I have a nifty USB voltage/amperage tester that I was using to measure the voltage/current/power draw of my iPhone 5s connected to one of those rechargeable battery power packs, and I kept seeing the phone, after some time, would report “accessory not supported” and stop charging. For the life of me, I couldn’t figure out why¹. The setup was running the battery pack into the USB tester, then to the phone. The USB Tester was plugged into my two Keithley 196’s, one measuring voltage, the other, current. Both were set to auto range². When you first plugin the phone, it would draw about 3/4 of an amp. It would then slowly draw less and less as the charge got higher and higher on the phone. Then at some point, it would stop charging.

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1. this is largely because I wasn’t paying attention to the meters all the time, so I didn’t notice the pattern right away [↩]
2. you might see where this is going now, if you’re paying attention [↩]