Do USB Power Meters Need External Power To Be Really Accurate?

Do USB Power Meters Need External Power To Be Really Accurate? Is there a real difference between USB power meters (USB power testers) which are using external power and the ones which are just using from the same power which they are testing or at least testing a part of it? Watch and see!

Here's the link to the one with external power:
AVHzY CT3+SM-LD-00 https://amzn.to/3MW1uIo

... and here the link to the one without external power (very similar to the one I've been showing in the video), which is much cheaper:
RD UM34 4A USB3.0 USB Meter Tester: https://amzn.to/35Tr4gB

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Disclaimer: The information provided on this video is for general purposes only based on my personal experience and are my very personal opinion, trying to help other people and should not be considered as professional advice in any kind. I am not a licensed professional so make sure to consult with your professional consultant in case you need to. All the links I provide in my videos, the description or in my feedback I provide in an effort to help you as good as I can, but I cannot give any warranty on them and hence you are using them on your own risk as I use them on my own risk.

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