3.7V/5V to 9V Boost Converter Module for Multimeter Mod – 2A Micro USB Adjustable, 18650 Lithium Battery Charging & Discharging Integrated Board

SKU: FA2120-4
Input Voltage

3.7V (lithium battery) or 5V (Micro USB)

Output Voltage

Up to 9V (adjustable)

Maximum Output Current

2A

Battery Type

18650 lithium-ion

Charging Input

Micro USB, 5V

Charging Management

Overcharge protection, status LEDs

Discharge Management

Over-discharge protection

Board Dimensions

Compact form factor for multimeter compartments

The 3.7V/5V to 9V Boost Converter Module is a compact, multi-functional power board designed specifically for modifying multimeters and other devices that require a stable 9V supply. It integrates 18650 lithium battery charging, boost voltage conversion, and discharge management into a single board, making it an ideal solution for replacing traditional 9V batteries with a rechargeable 18650 cell. The module also serves as a general-purpose boost converter for a wide range of portable electronics projects.

At the heart of the module is a high-efficiency boost converter that steps up the input voltage from either a 3.7V lithium battery or a 5V USB source to an adjustable output of up to 9V (or higher, depending on the configuration). The output voltage is set via an onboard potentiometer, allowing precise adjustment for your specific device requirements. The module can deliver up to 2A of output current, providing ample power for multimeters, portable instruments, and other 9V-powered devices.

The board features integrated 18650 lithium battery charging via a Micro USB input, allowing you to recharge the battery without removing it from the device. The charging circuit includes overcharge protection and charge status indication through onboard LEDs. This makes the module a complete, self-contained power solution — charge the battery, boost the voltage, and power your device, all from a single compact board.

The module includes discharge management with over-discharge protection, preventing the lithium battery from being drained below a safe voltage. This protects the battery and extends its lifespan, making the module suitable for long-term installations.

The compact form factor is designed to fit inside multimeter battery compartments and other tight spaces. The screw terminals or solder pads provide secure connections for the battery, input power, and output load. The module is widely used for multimeter modifications, portable instrument power, DIY power banks, and battery-powered projects requiring a stable 9V supply.

Whether you are upgrading a multimeter to rechargeable power, building a portable 9V power supply, or designing a custom battery-powered device, this Boost Converter Module provides a complete, efficient solution. It is suitable for individual makers, students, and businesses purchasing in bulk for product development or educational programs.


Features

  • 3.7V/5V to 9V boost conversion — Adjustable output voltage via onboard potentiometer

  • 2A maximum output current — Ample power for multimeters and portable instruments

  • Integrated 18650 lithium battery charging — Micro USB input for convenient recharging

  • Discharge management — Over-discharge protection extends battery lifespan

  • Charge status indication — Onboard LEDs show charging and full-charge status

  • Compact form factor — Designed to fit inside multimeter battery compartments

  • Multi-function design — Charging, boosting, and discharge management on one board

  • Adjustable output — Potentiometer allows precise voltage setting

  • Secure connections — Screw terminals or solder pads for reliable wiring

  • Wide application range — Multimeter mods, portable instruments, DIY power banks


Technical Specifications 

# Parameter Specification
1 Input Voltage 3.7V (lithium battery) or 5V (Micro USB)
2 Output Voltage Up to 9V (adjustable)
3 Maximum Output Current 2A
4 Battery Type 18650 lithium-ion
5 Charging Input Micro USB, 5V
6 Charging Management Overcharge protection, status LEDs
7 Discharge Management Over-discharge protection
8 Board Dimensions Compact form factor for multimeter compartments

Usage

Getting Started

  1. Install the 18650 battery — Insert a charged 18650 lithium battery into the battery holder or connect it to the B+ and B- pads.

  2. Charge the battery (optional) — Connect a Micro USB cable to the board’s Micro USB port and a 5V power source. The charge LED will indicate charging status. The red LED indicates charging; the blue/green LED indicates full charge.

  3. Adjust output voltage — Using a small screwdriver, turn the onboard potentiometer while measuring the output with a multimeter. Set the desired output voltage (typically 9V for multimeter applications).

  4. Connect the load — Connect your device (multimeter, portable instrument, etc.) to the OUT+ and OUT- terminals.

  5. Power on and test — The module will boost the battery voltage to the set output and power your device.

Important Notes

  • Output voltage adjustment — Always set the output voltage before connecting sensitive devices. Use a multimeter to verify the output.

  • Battery protection — The module includes over-discharge protection, but do not leave the battery in a discharged state for extended periods.

  • Heat dissipation — For sustained high-current operation, ensure adequate ventilation around the module.

  • Output current limit — The 2A maximum output current is achievable only under certain conditions. Higher output voltages may reduce the achievable current.

Typical Applications

  • Multimeter modification — Replace 9V batteries with rechargeable 18650 power

  • Portable instruments — Power test equipment, thermometers, and gauges

  • DIY power banks — Build custom 9V power supplies from lithium batteries

  • Battery-powered projects — General-purpose boost conversion for portable devices

  • Educational projects — Teaching boost converter and battery management principles

  • Field equipment — Reliable 9V power for remote or portable instruments

Notes for Business Buyers

  • Complete power solution — Charging, boosting, and discharge management on a single board.

  • Cost-effective — Replaces disposable 9V batteries with a rechargeable solution.

  • Compact design — Fits inside standard multimeter battery compartments.

  • Suitable for bulk purchasing — Ideal for multimeter manufacturers, electronics distributors, and educational institutions.

Q: What is the 3.7V/5V to 9V Boost Converter Module used for?

It is a multi-function power board for modifying multimeters and other 9V-powered devices, integrating 18650 battery charging, boost voltage conversion, and discharge management.

Q: What is the input and output voltage?

Input: 3.7V (lithium battery) or 5V (Micro USB) . Output: Up to 9V (adjustable).

Q: What is the maximum output current?

The module can deliver up to 2A output current.

Q: How do I adjust the output voltage?

Use a small screwdriver to turn the onboard potentiometer. Measure the output with a multimeter to set the desired voltage.

Q: Does it charge the 18650 battery?

Yes. The module includes integrated 18650 lithium battery charging via the Micro USB port, with overcharge protection and charge status LEDs.

Q: Does it protect the battery from over-discharge?

Yes. The module includes over-discharge protection to prevent the lithium battery from being drained below a safe voltage.

Q: What is the charging input voltage?

The charging input is 5V via Micro USB.

Q: Can I use this module to power a multimeter?

Yes. It is specifically designed for multimeter modifications, providing a stable 9V output from a rechargeable 18650 battery.

Q: How long does the battery last?

Battery life depends on the battery capacity and the load current. A typical 18650 battery (2000–3500mAh) can power a multimeter for many hours or days of typical use.

Q: Can I purchase in bulk for a product development project?

Yes. This module is suitable for both individual users and business purchasing, including multimeter manufacturers, electronics distributors, and educational institutions.