[Review] YZX Studio USB 3.0 Power Monitor [English]
Because there’s not that much information around on these power monitors,
I decided to translate my Dutch review into English, because the Dutch review ends up quite high in the results from a Google search on YZXStudio...
For my Dutch readers, sorry 'bout the repost
After my curiosity was piqued by a review from Julian Ilett I wanted to check these power monitors out myself.
A quick Google-around didn’t deliver that much information, there’s not a lot written about these monitors, other than the YouTube-reviews by Julian and Martin Lorton and a short thread on the EEVBlog forum.
In the search results you’ll come across a blue version too, this is identical in function to the yellow power monitor. Take note that there are multiple hardware versions of these monitors. There are 2 PCB and 3 PCB versions, the latter being the most recent.
This kind of power monitor is a bit more than just your ordinary USB-tester regarding accuracy.
Measurements are very accurate with error margins supplied below :
Voltage 1%+5d; Current 0.2%+2d; Ah capacity 0.5%; Wh capacity 1.5%
Firmware is user-upgradeable with an STM32 dongle. Supplied with the kit when you order it are some DuPont cables and 4 pogopins, which fit in the connectors of the DuPont cables.
While writing this review I tested the firmware-upgrade process by following Julian’s video-walkthrough.
Another distinction from other testers is the number of digits : a resolution of 1 mV and 0,1mA and a refreshrate of 0,36 seconds.
Both power monitors display the info on a small, non-glossy old screen (0.91" 128x32 pixels) but what sets them apart from other power monitos is that they can both display a graphical power or current curve. Besides that they both have 10 memory slots to store results.
Change between modes with a short buttonpress. A long buttonpress moves to the next slot while resetting it to 0. In modes where you can enter parameters you switch to with 2 buttonpresses.
Firmwareversion V2.5 adds some more functions :
a mode with measurement of resistance, time and temperature and trickle-charge-ignore-level.
and another ‘simple’ meter that displays volts and amps in a bigger font.
When displaying curves these now scale too.
The red version and the yellow version differ from another on one specific feature : the yellow power monitor can change output-mode, while the red power monitor analyses the output-mode. It does this by checking the resistors on the D+ and D- lines in the USB connector.
This is also the reason for 2 different meters, the yellow version has an array of resistors to simulate different output-modes, the red one does not.
As stated before, the red version analyses the output-mode and displays the following :
Apple, Android DCP, Samsung or normal usbports with mention of the max. output current.
The yellow version can switch between Fast Charge, Disconnect mode and USB Direct Mode.
When you enter the settings (which you do by keeping the button pressed while starting up) you can calibrate your monitor to a 5V reference and a 2A reference, change the update rate of the curves, change brightness, rotate and/or invert the display, set the trickle charge ignore level, set a time for screen blanking, reset to factory settings, backup and restore your own settings.
On top of that you can also change the font, set temperature drift and enable or disable serial upload (with some extra hardware you can monitor the serial output and do stuff with it by using a UART USB/Serial adapter, Bluetooth or Wifi module).
Both meters have an input voltage ranging from 3,5V to 13V, and input current rated to 3A, so they’re also usable when testing devices that support Qualcomm’s Quickcharge 2.0-standaard.
They’re not the most budget-friendly power monitors, I must admit that, and the firmware upgrade is a bit of a hassle, but if you’e serious about measuring and analysing what goes into and/or out of your USB-port regarding power, these are some darn nice thingamajigs.
Power-usage of these monitors is, with an average of 0,007A, not really an issue.
(according to the specs 0,006A with the display on en 0,0045A with the display off)
If you’d like to order some for yourself, checkout Franky Tong on eBay.
Red YZXStudio USB 3.0 Power Monitor
Yellow YZXStudio USB 3.0 Power Monitor
Firmware upgrade kit (dongle + pogo pins + DuPont leads)