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Tags Reviews  UM25 

Not a real review, but I had one for a while now. Decided to buy another one (with Bluetooth) and make a small application for it. Also used this to hack a serial port on the first one.

This (and a dummy load) has been one of the more useful and used tools I bought in a long time. Below is the README.

UM25C

The UM25(C) is an USB Power Meter by RD Tech. It can be found for less then €20 on AliExpress.

The specifications are:

• Display
  • 1.44″ color LCD display
  • 0-5 brightness setting
  • Auto screen off time – 0 to 9 minutes
  • Refresh rate – 2Hz
• Measurement Range & Accuracy
  • Voltage – 4-24.000V ±0.5‰ + 2digits
  • Current – 0-5.0000A ±1‰ + 4 digits
  • Capacity – 0-99999mAh
  • Energy accumulation – 0-99999mWh
  • Load impedance – 0.8Ω-9999.9Ω
  • Time range – 0-99h59min59s
  • Temperature range – -10℃ to 100℃ ±3℃
• Connectivity – Bluetooth (C model)
  • USB – 1x USB male port, 1x USB female port, 1x micro USB port, 1x USB 2.0 type C port
  • Quick charge recognition mode – QC2.0, QC3.0, APPLE 2.4A/2.1A/ 1A/0.5A, Android DCP for SAMSUNG
  • Misc – 4 buttons to navigate menus, Bluetooth switch
• Dimensions – 71.2mmx30.5mmx12.4mm(UM25C)
  • Weight – 23.74g

It comes with a android and windows application for logging.

This tool is can be used to log the following samples:

• Amperage (A)
• Voltage (V)
• Wattage (W)
• Temperature (C).
• Data group Summed Amp (Ah)
• Data group Summed Watt (Wh)

(more to be added in future)

It outputs the samples to standard out.

This tool does not handle the bluetooth connection, use bluetoothct/blueman for this. You connect to the /dev/rfcomm0 device.

You can also use this with an UM25 via a USB to serial cable.

The logfile can then be parsed f.e. gnuplot:

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