HW-357 1S Li-ion Charger with Adjustable 4.3–27V Step-Up Converter

HW-357 Battery Charger and Step-Up Module

The HW-357 Battery Charger Step-Up Module combines two functions on one compact board. It charges a single 3.7V lithium battery and boosts its voltage to an adjustable output.

The charging section provides linear CC/CV charging up to 4.2V. Meanwhile, the step-up converter can supply an adjustable output from approximately 4.3V to 27V.

Key Features

• Charges one 3.7V Li-ion or LiPo cell
• Provides an adjustable 4.3V–27V output
• Supports up to 1A charging current
• Accepts power through Micro USB
• Includes separate input solder pads
• Provides battery and output connection pads
• Supports output operation during charging
• Includes charging-status LEDs
• Offers a compact solution for portable projects

Technical Specifications

• Model: HW-357 / J5019
• Battery Configuration: 1S
• Compatible Battery: 3.7V Li-ion or LiPo
• Input Voltage: 4.5V–8V DC
• Recommended Input Voltage: 5V DC
• Input Connector: Micro USB
• Battery Charging Voltage: 4.2V ±1%
• Maximum Charging Current: Up to 1A
• Charging Method: Linear CC/CV
• Adjustable Output Range: Approximately 4.3V–27V
• Maximum Battery-Side Discharge Current: Approximately 2A
• Quiescent Current: Approximately 0.5mA
• Operating Temperature: Approximately -20°C to +85°C
• Dimensions: Approximately 33 × 23 × 5mm

Approximate Output Capability

The available output current decreases as the selected voltage rises. For example:

• 5V Output: Up to approximately 1.4A
• 9V Output: Up to approximately 0.8A
• 12V Output: Up to approximately 0.6A

However, actual performance depends on the battery, input source, cooling, wiring, and converter efficiency.

Connection Pads

• VIN+: Positive charging input
• VIN-: Negative charging input
• BAT+: Positive battery terminal
• BAT-: Negative battery terminal
• OUT+: Positive adjustable output
• OUT-: Negative adjustable output

How to Use

1. Connect a protected 3.7V lithium cell to BAT+ and BAT-.
2. Check the battery polarity carefully.
3. Supply a stable 5V through Micro USB or VIN.
4. Measure the output with a multimeter.
5. Adjust the potentiometer to the required voltage.
6. Disconnect the load before making large adjustments.
7. Connect the load after confirming the output voltage.

Applications

Use the HW-357 module for:

• Portable adjustable power supplies
• Battery-powered electronics
• DIY power banks
• Multimeter modifications
• Robotics projects
• Sensor systems
• Rechargeable test equipment
• Backup power experiments
• Embedded electronics

Charging and Protection Notes

The module can power its output while charging the battery. However, a heavy load may affect charge detection and termination.

In addition, the board does not provide reliable low-voltage battery disconnection. Therefore, use one of the following:

• A protected 18650 battery
• A separate 1S protection board
• A suitable 1S BMS
• An external low-voltage cutoff circuit

Package Contents

• 1 × HW-357 charger and adjustable step-up converter module

Important Notes

• Use this module with one lithium cell only.
• Do not connect multiple cells in series.
• The board does not provide complete over-discharge protection.
• Check the polarity before connecting the battery.
• Reverse polarity may damage the module.
• Measure the output voltage before connecting sensitive equipment.
• Do not exceed the battery’s safe charge or discharge current.
• Avoid running a heavy load while charging.
• The module is not a regulated solar charge controller or MPPT controller.
• Components and LED colors may vary between batches.