2 in 1 4.5V-40V Voltmeter & 5V USB Charger Step-Down Buck Power Converter Module / USB Charger Board

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  • Regular price $5.29
  • 7 available

This unique dual function DC-DC Buck step-down voltage converter and USB charger accepts 4.5V to 40V input and provides an LED voltmeter to monitor the input voltage.  With input voltages from 6.5V to 40V, it will generate a regulated 5V USB output at up to 2A.

This module can be powered by a battery, solar panels or an energy storage bank, and provide the +5V regulated USB power needed to power or charge a cell phone, MP3 player, tablet, or any device that is powered by 5V USB power. It is ideal for camping and off-grid uses.


  • Car / motorcycle battery voltage monitoring, solar panel energy storage monitoring or other voltage measurements.
  • USB Charger for mobile phone, MP3 player, Tablet PC or other electronic products.


  • Input voltage/ voltmeter range: DC 4.5~40V, (with input voltage from 6.5V to 40V, can generate a 5.0V regulated output)
  • Output voltage/current: 5V/2A
  • Voltmeter display can be calibrated
  • Reverse polarity, over current and over temperature protection
  • Output enable button turns On/Off the USB output power. USB power indicator LED illuminates when output is enabled
  • Lower Power button disables output and display and puts module in a low power mode 
  • High-efficiency, low ripple
  • Dimensions: 58mm * 21mm * 10mm (L*W*H)
  • Net weight: 13g

Instructions for use:

  • At power-on, the voltmeter digital display will display the input voltage level. 
  • To charge or power a phone, Tablet PC, or MP3 player, press the "Output Enable" button. The USB power indicator will illuminate, and 5.0V will be applied to the USB output connector and the output solder pads. 
  • To turn off the digital display, press the "Low Power" button. The module will enter the low-power standby mode, the display will be disabled and the USB output shut down.

Voltmeter calibration:

  • With power applied to the module, and voltage is displayed on the LED meter, press and hold the "Output Enable" button for 2 seconds then release, the voltmeter will flash.
  • Touch the "Output Enable" button, the voltage increases one unit, touching the "Low Power" button will reduce the voltage by one voltage reduction unit (one unit is less than 0.1V).
  • After the voltage calibration is completed, press the "Output Enable" button for 2 seconds then release to exit voltage calibration mode. When powered off, parameter settings will automatically be saved.

Package includes:

1x DC/DC Converter Digital Voltmeter Display USB Charger
User Guide & Documentation

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