{"product_id":"2-in-1-dc-voltmeter-5v-usb-charger-buck-converter-module","title":"2-in-1 DC Voltmeter \u0026 5V USB Charger Buck Converter Module (4.5V-40V Input)","description":"\u003ch2\u003e📋 Overview\u003c\/h2\u003e\n\u003cp\u003eThe 2-in-1 DC Voltmeter \u0026amp; 5V USB Charger Buck Converter Module (HW-318) is a compact DC-DC step-down power converter that combines two useful functions into a single board: a real-time 3-digit red LED voltmeter that monitors your input voltage, and a regulated 5V USB-A output capable of delivering up to 2A for charging phones, tablets, GPS units, and other USB devices.\u003c\/p\u003e\n\u003cp\u003eThe module accepts a wide input voltage range of DC 4.5V to 40V, making it compatible with 12V and 24V automotive systems, solar panels, battery packs, and bench power supplies. Built-in protections for reverse polarity, overcurrent, and over-temperature make it a safe and practical choice for a wide range of power applications.\u003c\/p\u003e\n\u003cp\u003eTwo on-board buttons — \"Enable Output\" and \"Low Power\" — give you control over the USB output and standby mode, while a simple calibration procedure lets you fine-tune the voltmeter accuracy to ±0.1V.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch2\u003e🔧 How It Works\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eConnect your DC power source (4.5V–40V) to the screw terminals on the module — positive to IN+, negative to IN−.\u003c\/li\u003e\n\u003cli\u003eThe LED voltmeter lights up immediately and displays the input voltage.\u003c\/li\u003e\n\u003cli\u003ePress the \"Enable Output\" button to activate the 5V USB port.\u003c\/li\u003e\n\u003cli\u003ePlug a standard USB cable into the USB-A port and connect it to your device — charging begins automatically.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cblockquote\u003e\n\u003cp\u003e\u003cstrong\u003e💡 Tip:\u003c\/strong\u003e The USB output requires a minimum input voltage of 6.5V to produce a stable 5V output. Below 6.5V, the voltmeter will still display the input voltage, but the USB output may not function correctly.\u003c\/p\u003e\n\u003c\/blockquote\u003e\n\u003chr\u003e\n\u003ch2\u003e⭐ Key Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e2-in-1 Design:\u003c\/strong\u003e Combines a DC voltmeter and a 5V USB charger in a single compact module\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWide Input Range:\u003c\/strong\u003e Accepts DC 4.5V to 40V — compatible with 12V and 24V automotive systems, solar panels, and battery packs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRegulated 5V USB Output:\u003c\/strong\u003e Delivers up to 2A through a standard USB-A port for charging smartphones, tablets, GPS units, and other USB devices\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e3-Digit LED Voltmeter:\u003c\/strong\u003e Red LED display continuously monitors the input voltage with ±0.1V accuracy (after calibration)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBuilt-In Protections:\u003c\/strong\u003e Reverse polarity protection, overcurrent protection, and over-temperature protection\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOn-Board Control Buttons:\u003c\/strong\u003e \"Enable Output\" button to turn the USB port on\/off, and \"Low Power\" button for standby mode\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLED Status Indicators:\u003c\/strong\u003e Separate LEDs indicate USB power status and input terminal wiring status\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUser-Adjustable Calibration:\u003c\/strong\u003e Voltmeter display can be calibrated using the on-board buttons for improved accuracy\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScrew Terminal Input:\u003c\/strong\u003e Secure, solderless connection for your DC power source\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact and Lightweight:\u003c\/strong\u003e Just 58 × 21 × 10 mm and 13g — fits easily into enclosures, dashboards, and portable projects\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003ch2\u003e📐 Specifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eModel\u003c\/td\u003e\n\u003ctd\u003eHW-318\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eModule Type\u003c\/td\u003e\n\u003ctd\u003eDC-DC Buck (Step-Down) Converter with Voltmeter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Voltage (Voltmeter Range)\u003c\/td\u003e\n\u003ctd\u003eDC 4.5V – 40V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Voltage (for 5V USB Output)\u003c\/td\u003e\n\u003ctd\u003eDC 6.5V – 40V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput Voltage\u003c\/td\u003e\n\u003ctd\u003e5V DC (regulated)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput Current (Max)\u003c\/td\u003e\n\u003ctd\u003e2A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput Connector\u003c\/td\u003e\n\u003ctd\u003eUSB-A female port\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVoltmeter Display\u003c\/td\u003e\n\u003ctd\u003e3-digit red LED\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVoltmeter Accuracy\u003c\/td\u003e\n\u003ctd\u003e±0.1V (after calibration)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProtections\u003c\/td\u003e\n\u003ctd\u003eReverse polarity, overcurrent, over-temperature\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Connection\u003c\/td\u003e\n\u003ctd\u003eScrew terminals (+ and −)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eControl Buttons\u003c\/td\u003e\n\u003ctd\u003eEnable Output, Low Power (standby)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLED Indicators\u003c\/td\u003e\n\u003ctd\u003eUSB power status, terminal wiring status\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003eApprox. 58 × 21 × 10 mm (2.28 × 0.83 × 0.39 inches) L × W × H\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003eApprox. 13g\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003chr\u003e\n\u003ch2\u003e📌 Connections\u003c\/h2\u003e\n\u003ch3\u003eInput (Screw Terminals)\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eTerminal\u003c\/th\u003e\n\u003cth\u003eLabel\u003c\/th\u003e\n\u003cth\u003eDescription\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePositive\u003c\/td\u003e\n\u003ctd\u003eIN+\u003c\/td\u003e\n\u003ctd\u003eConnect to the positive terminal of your DC power source (4.5V–40V)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNegative\u003c\/td\u003e\n\u003ctd\u003eIN−\u003c\/td\u003e\n\u003ctd\u003eConnect to the negative \/ ground terminal of your DC power source\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eOutput\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eConnector\u003c\/th\u003e\n\u003cth\u003eDescription\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eUSB-A Port\u003c\/td\u003e\n\u003ctd\u003eRegulated 5V output at up to 2A — plug in any standard USB cable to charge your device\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eOn-Board Controls\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eButton \/ Indicator\u003c\/th\u003e\n\u003cth\u003eFunction\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eEnable Output Button\u003c\/td\u003e\n\u003ctd\u003eTurns the USB 5V output on or off\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLow Power Button\u003c\/td\u003e\n\u003ctd\u003ePuts the module into standby mode to reduce power consumption\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUSB Power LED\u003c\/td\u003e\n\u003ctd\u003eIndicates whether the USB output is active or disabled\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTerminal Status LED\u003c\/td\u003e\n\u003ctd\u003eIndicates correct input wiring polarity\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003chr\u003e\n\u003ch2\u003e📦 What's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1× 2-in-1 DC Voltmeter \u0026amp; 5V USB Charger Buck Converter Module (HW-318)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eUSB cable, power source, and mounting hardware are not included.\u003c\/em\u003e\u003c\/p\u003e\n\u003chr\u003e\n\u003ch2\u003e🛒 What You'll Need\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDC Power Source (4.5V–40V)\u003c\/strong\u003e — Battery, power supply, solar panel, or vehicle electrical system\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWire\u003c\/strong\u003e — Appropriately rated wire for your input voltage and current (22 AWG minimum for 2A loads)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSmall Flathead Screwdriver\u003c\/strong\u003e — For tightening the screw terminals\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUSB Cable\u003c\/strong\u003e — Standard USB-A cable to connect to your device for charging\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003ch2\u003e🎯 Typical Applications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAutomotive USB charger:\u003c\/strong\u003e Connect to a 12V or 24V vehicle battery to charge phones and tablets\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSolar panel projects:\u003c\/strong\u003e Step down solar panel voltage to 5V for charging USB devices off-grid\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBattery monitoring:\u003c\/strong\u003e Monitor battery voltage while simultaneously providing USB charging\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBench power supply add-on:\u003c\/strong\u003e Add a USB charging port and voltmeter to your workbench power supply\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePortable power packs:\u003c\/strong\u003e Build a custom portable charger with voltage monitoring\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRC and drone projects:\u003c\/strong\u003e Monitor LiPo battery voltage while powering USB accessories\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMarine and RV installations:\u003c\/strong\u003e Charge devices from 12V\/24V DC systems with voltage monitoring\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEducational projects:\u003c\/strong\u003e Learn about DC-DC buck conversion, voltage regulation, and power electronics\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003ch2\u003e⚠️ Important Notes\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eInput voltage limits:\u003c\/strong\u003e Do not exceed 40V DC input. The voltmeter functions from 4.5V, but the USB output requires at least 6.5V input to produce a stable 5V output.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaximum output current:\u003c\/strong\u003e The USB port is rated for 2A maximum. Do not use this module to charge devices that draw more than 2A.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHeat dissipation:\u003c\/strong\u003e At high input voltages (24V–40V) and high output currents (close to 2A), the module will generate heat. Ensure adequate ventilation and consider adding a small heatsink if the module becomes excessively hot.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot a fast charger:\u003c\/strong\u003e This module provides standard 5V USB power at up to 2A. It does not support Qualcomm Quick Charge, USB Power Delivery (PD), or other fast-charging protocols.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVoltmeter accuracy:\u003c\/strong\u003e The LED voltmeter is accurate to approximately ±0.1V after calibration. For precision measurements, use a calibrated multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWire gauge:\u003c\/strong\u003e Use appropriately rated wire for your input voltage and current. For 2A loads, use at least 22 AWG wire. For longer runs, use thicker wire to minimize voltage drop.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDC input only:\u003c\/strong\u003e This module is designed for DC input only. Do not connect to AC mains power.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003ch2\u003e📄 Documentation \u0026amp; Resources\u003c\/h2\u003e\n\u003ch4\u003eDocumentation\u003c\/h4\u003e\n\u003cp\u003eFull wiring instructions, calibration procedure, and technical details are available at the Envistia Mall product support website.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/envistiamall.com\/blogs\/learn\/2-in-1-dc-voltmeter-5v-usb-charger-buck-converter-module-user-guide\" target=\"_blank\" title=\"2-in-1 DC Voltmeter \u0026amp; 5V USB Charger Buck Converter Module User Guide\" rel=\"noopener\"\u003eUser Guide\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/envistiamall.com\/blogs\/learn\/tagged\/buck-converters\" target=\"_blank\" title=\"All Buck Step-Down Converter User Guides\" rel=\"noopener\"\u003eAll Buck Step-Down Converter User Guides\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003cp\u003e\u003cem\u003eSold and supported by \u003ca rel=\"noopener noreferrer\" href=\"https:\/\/envistiamall.com\" target=\"_blank\"\u003eEnvistia Mall\u003c\/a\u003e. Ships from the USA. For wiring diagrams, calibration instructions, and troubleshooting, see the User Guide linked above. The manufacturer and Envistia LLC (dba Envistia Mall) are not responsible for any damages or losses resulting from the use of this product. Always follow proper electrical safety practices when working with electronic components. Specifications are based on manufacturer data and are subject to change without notice.\u003c\/em\u003e\u003c\/p\u003e","brand":"Envistia","offers":[{"title":"Default Title","offer_id":28453660169,"sku":"EM-POWER-0005","price":4.29,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1641\/0911\/products\/2-in-1-45v-40v-voltmeter-5v-usb-charger-step-down-buck-power-converter-module-usb-charger-board-945687.jpg?v=1617838444","url":"https:\/\/envistiamall.com\/products\/2-in-1-dc-voltmeter-5v-usb-charger-buck-converter-module","provider":"Envistia Mall","version":"1.0","type":"link"}