Two fascinating USB 3.0 power monitors which have super accurate voltage, current and power measurement and some really neat additional features.
USB 3.0 Power Monitor - YZXstudio Voltage Current Meter OLED Charger Doctor #YZXstudio http://www.ebay.com/itm/USB-3-0-Power-Monitor-YZXstudio-Voltage-Current-Meter-OLED-Charger-Doctor-/171657443908
USB 3.0 Power Monitor (Red) YZXstudio Voltage Current Meter High Resolution OLED http://www.ebay.com/itm/USB-3-0-Power-Monitor-YZXstudio-Voltage-Current-Meter-High-Resolution-OLED-/171606912751
Disclosure: These items were supplied to me at no cost for the purpose of making a review video.

By Julian

Youtuber, shed dweller, solar charge controller aficionado

13 thoughts on “Julian’s postbag: #42 – usb 3.0 power monitors red/yellow”
  1. Avataaar/Circle Created with python_avatars Nick's Stuff says:

    Any info on more modern USB-C meters?

  2. Avataaar/Circle Created with python_avatars Taran Agnew says:

    what do you use usb Power Monitors for?

  3. Avataaar/Circle Created with python_avatars J Allen says:

    So the ports on the bank are labeled as they are because when a load is placed on both ports the current is lowered on the one indicated so the current both parts together limited to 3 amps the USB standard maximum?
    I suggest putting one meter on each port at the same time with a load greater than 3 amps to test this

  4. Avataaar/Circle Created with python_avatars Chemicalvamp says:

    Unfortunately these models from YZX aren't currently available.

  5. Avataaar/Circle Created with python_avatars Popart 2015 says:

    What about the new ones…

  6. Avataaar/Circle Created with python_avatars Troy Belding says:

    I suspect that 'disconnect' is oriented to disallow data flow between device and PC. That is, so your iPhone or Android doesn't show up as a USB device on your computer.

  7. Avataaar/Circle Created with python_avatars James Holbrook says:

    they say 4 to 13v you should try them with some fast chargers that use 9v and 12v

  8. Avataaar/Circle Created with python_avatars Lew Whitbourn says:

    I think the purpose of the voltages on the data pins is to TELL the device being charged that it can draw the current that it requires. There do not seem to be any proper standards in this space (yet?), so devices are not smart enough to know that that a 2 Amp supply (or a 3 Amp supply) is good for anything less than 2 Amps, etc. So, some Android devices need to be told that they can draw 1.5 A, exactly, and some Apple devices need to be told that they can draw 2.0 Amps or 2.1 Amps, etc. I wonder what the tolerances on the voltages are, and whether a lack of standardisation on such things leads to some of the ambiguous interpretations by the YZXstudio red device. Obviously the manufacturer of the YZXstudio devices has to have a look-up table of all the current "standards" and that must be quite difficult to keep up with. Does anyone know whether there is a published list somewhere?

  9. Avataaar/Circle Created with python_avatars someone you don't know says:

    too expensive !

  10. Avataaar/Circle Created with python_avatars The Moto fixery says:

    so i just want to test the multiple wall, car, and portable usb chargers that i use to see witch ones are faster. so witch one of these would be better to get? the red one gives you a little info on what the plug is intended for but the yellow one fools the device into a fast charge mode… would that be better for testing the full output of a charger? or just ruin stuff like some of the comments suggest?

  11. Avataaar/Circle Created with python_avatars Vitesse Pilot says:

    Can these units measure the power draw from something like a USB 3.0 Flash drive ?

  12. Avataaar/Circle Created with python_avatars Seamus de Mora says:

    Fascinating stuff – makes you understand that you can't always depend on the manufacturer's (or vendor's) specifications. Just one note, however: Don't confuse precision with accuracy; the fact that these devices display I & V to 3 or 4 decimal places has nothing to do with the accuracy of their measurements.

  13. Avataaar/Circle Created with python_avatars Alfredo Coronado says:

    Last night I saw a long list of people asking for their money back. Damn Banggood fucking company 9 years scamming people around the world. MADE IN CHINA.

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