DC-DC 4.5-40V To 5V 2A USB Charger Step down Converter Voltmeter Module

From the shop's description

This is DC-DC 4.5-40V To 5V 2A USB Charger Step down Converter Voltmeter Module, a combo of 2A Charger and voltage checker. The module converts input of 4.5-40V into a very stable 5V 2A output. The device features a USB port through which you can charge your phone. While charging your device please consider that the output of this device is regulated at 5V 2A. Simply connect this device to the power supply, the voltage can be detected in real time. When you need the phone, IPAD, MP3 and other digital products to charge, click the “Output Enable” button, then USB power indicator lights up and it will start supplying 5V 2A at its output. When you need to turn off the voltmeter, click the “Low Power” button, then enter the ultra-low-power standby mode, USB output corresponding shutdown. It accepts wide input voltage as from car/battery car/motorcycle used for monitoring battery voltage; measure the voltage needed for a variety of occasions. The output current capability 5.0V/2A, enough to meet a variety of USB devices. Note: This module default D + D- short, most of the cell phone charger is compatible, and set aside a variety of mobile phones identification resistor installation location, if you need to add the identification resistor, please connect D + D- wires cut, then added. Voltmeter Calibration Method Step1: Press the “ Output Enable ” button more than 2 seconds, release, voltmeter flashes, this time into the voltage regulation mode; Step2: Press the “ Output Enable ” button (normal speed), the voltage value is adding up a unit; Press the “ Low Power ” button, minus a unit; Due to a unit is less than 0.1V, the minimum voltage display to 0.1V, so you need to continuously press 1-5 times to see the voltmeter change 0.1V, how many times voltmeter change 0.1V by pressing the button, depending on the current display voltage, the higher the voltage, the fewer the number of press. Step3: press the “ Output Enable ” button for more than 2 seconds, release, to exit the voltage calibration mode. Data is not lost after the power failure. Application: Cars and Electric Bikes Motorcycle for voltage measurement and to charge the phone iPads, Mobile Phones Mp3 Devices Features : The voltmeter has an automatic calibration function. With reverse connection protection. With overheat protection and short circuit protection. High efficiency and low ripple. With USB power indicator light. Package Includes : 1 x DC-DC 4.5-40V To 5V 2A USB Charger.