CN3791 MPPT Solar Battery Charger Module 3.7V 4.2V 12V JST

CN3791 MPPT Solar Battery Charger Module – 3.7V/4.2V, 12V Input, 300KHz PWM

Power your lithium-ion battery projects more efficiently with the CN3791 MPPT Solar Charging Board. Designed for 12V solar panels, this compact module automatically tracks the maximum power point of your solar input, ensuring you extract every last watt of available energy — even as light conditions change throughout the day. Perfect for DIY solar charging stations, remote sensors, battery-powered devices, and portable electronics projects.

Made in Mainland China.

Key Features

• Automatic MPPT Technology: Continuously tracks and locks onto the solar panel's maximum power point, optimising energy harvest without manual adjustment.
• Easy Plug-and-Play Setup: Connect your 12V solar panel to one side and your lithium polymer (LiPo) battery to the other via the pre-installed 2-pin JST/PH2.0 connectors — no soldering required.
• Comprehensive Charge Management: Supports trickle charging for deeply discharged batteries, automatic recharging, and visual status indicators for charging and charge-complete states.
• Flexible Current Settings: Constant current charging is set via an external resistor, allowing you to customise charge current up to 2A for your specific battery capacity.
• High-Frequency PWM Switching: 300KHz switching frequency minimises ripple and improves efficiency for cleaner, more stable charging.
• Parallel Load Support: Powers a connected load in parallel with the battery during charging — ideal for always-on devices.

Technical Specifications

What's in the Box

• 1 × CN3791 MPPT Charging Module

Important Notes

This module is designed for use with a 12V nominal solar panel. Ensure your solar panel's working voltage matches 12V for correct MPPT operation. Color may vary slightly from photos due to monitor calibration. Please allow ±1–2cm measurement deviation due to manual measurement.

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For more information on solar energy standards and safe electrical practices, visit the U.S. Department of Energy – Solar Energy Technologies Office.

Frequently Asked Questions

Q: What type of battery is compatible with the CN3791 MPPT charging module?

A: The CN3791 charging module is designed for single-cell lithium-ion or lithium polymer (LiPo) batteries with a nominal voltage of 3.7V and a full-charge voltage of 4.2V. It is not suitable for multi-cell packs or other battery chemistries such as NiMH or lead-acid without modification.

Q: What solar panel do I need to use with this module?

A: This CN3791 MPPT module requires a solar panel with a working (nominal) voltage of 12V. Using a panel with a different voltage may result in improper operation or damage to the module or battery.

Q: How do I set the charging current for my battery?

A: The constant current charging level is configured via an external resistor on the board. By selecting the appropriate resistor value, you can set the charge current up to a maximum of 2A. Consult the CN3791 datasheet for the specific resistor-to-current formula.

Q: Does the module support charging while simultaneously powering a load?

A: Yes. The CN3791 module supports a load connected in parallel with the battery. This means your connected device can continue to operate while the battery is being charged from the solar panel.