YZXStudio USB meter ZY1263



Official specifications:

• Input voltage: DC 3.5V-24V
• Input current: +- 3A
• Voltage resolution: 0.0001V (0.1mV)
• Current resolution: 0.0001A
• Cumulative capacity: 0-99999Ah; 0-99999Wh
• Capacity resolution: 0.0001Ah; 0.0001Wh
• Accuracy: Voltage 0.1%+2d; Current 0.2%+2d; Ah capacity 0.5%; Wh capacity 0.5%
• Display: 1" 128x64 pixel LCD with backlight
• Update rate: Every 0.36s
• Idle current consumption: ~10mA/5mA (with backlight on/off)
• Current shunt resistance: 10mOhm
• Overall circuit resistive loss: ~42mOhm (including contact resistance on USB connectors)
• Memory: FRAM, good for 10 billion write cycles
• Memory operation mode: write on every update in cumulative capacity + load balancing technique

I got it from ebay dealer f-t-2000, he is also known as Franky or 99centhobbies

YZXStudio makes a series of usb meters with nearly identical specifications, there is also frequent software update with significant improvements. It is possible to install update, but it requires special tools and access to the updated software (The above shop sells the tool and gives access to the updates).



This table compares some of the YZXStudio usb meters.



How does it look









Notice the small button, it is used for all the functions.





Welcome screen, it is shown when power is applied, in software v2.9 and above it can be disabled.



The first screen, it shows V, A, Ah and time, the "1" is selected memory bank.



Next screen shows Wh and W, instead of Ah and time.



This screen shows usb coding and voltage. From voltage and current the resistance of the load is calculated and shown. It also shows the trickle current threshold, only current above this value is summed (Value is configurable). The temperature is the internal MCU temperature.
Note: Sometimes the display will show two usb codings, because it cannot determine which one is valid.



A chart of current and voltage, sample rate can be configured.



These usb meters are very easy to open, there is only 8 screws to remove.





LCD display with a led in the frame.





I am guessing a bit with these chips: 7133 is a 3.3 volt regulator, CBVV is a 18 bit ADC with build in amplifier, FM24CL is the FRAM memory. DALE R012F is the series resistor that is used to measure current over.
The microprocessor is hidden beneath the flex cable.



Measurements



The voltage display is very precise with no current flowing (Both voltage and current can be calibrated by the user, I have not changed the calibration, but the dealer may have).
Note: At 3.5 volt the meter restarted all the time.



The current display is also very precise and will not change with voltage.

• The tested usb meter uses software V2.8+
• The voltage readout is within 0.005 volt when unloaded (Very good).
• When loaded the voltage will be closest to the usb input voltage.
• Current is within 0.003A.
• The usb meter uses about 10.7mA current with backlight on, 5.6mA with backlight low.
• The internal resistance is about 0.09ohm (This includes both connectors).

M1: 35,5°C, HS1: 38,6°C
THe above IR photo was taken after 30minutes with 3A, during that time the voltage readout changed 0.2% and current readout 0.03%



Conclusion

This is a very precise usb meter with many interesting functions. I only have one problem with it: it often ignores button presses (This might be fixed in the latest software version).



Notes

For these USB meters I used very precise equipment (Keithley: DMM7510, 2280S, 2460).

How do I make the test