Solar Power Manager For 12V Lead-Acid Battery

Solar Power Manager Series


The DFRobot Solar Power Manager series are designed for IoT and renewable energy projects, providing safe and high-efficiency embedded solar power management modules for makers and application engineers. All modules in this series have MPPT (Maximum Power Point Tracking) to maximize solar energy conversion efficiency under various sunlight. A complete battery and power protection provides reliable power management for different types of solar projects.

Selection Guide

Name Solar Power Manager 1.0V Solar Power Manager 5V V1.1 Solar Power Manager Micro V1.0 Solar Power Manager For 12V Lead-Acid Battery V1.0
SKU DFR0535 DFR0559 DFR0579 DFR0580
Solar Power Management IC LTC3652 CN3065 SPV1050 CN3767
Solar Input Voltage 7V ~ 30V 4.4V ~ 6V 0.5V ~ 4V 15V ~ 25V
Maximum Charge Current (Solar) 2A (Solar/USB) 900mA (Solar/USB) 70mA (Solar)/100mA (USB) 4A (Solar)
Topology DC-DC Buck Linear Regulator DC-DC Boost DC-DC Buck
Battery 3.7V Lithium Battery 3.7V Lithium Battery 3.7V Lithium Battery 12V Lead-Acid Battery
MPPT 9V/12V/18V Optional Fixed 5V 75% Open Voltage Fixed 18V
Battery Protections Over Charge/Over Discharge/Over Current/Reverse Connection Protections Over Charge/Over Discharge/Over Current/Reverse Connection Protections Over Charge/Over Discharge/Reverse Connection Protections Over Charge/Over Discharge/Reverse Connection Protections
Output Protections Short Circuit/Over Current/Over Heat Protections Short Circuit/Over Current Protections Short Circuit/Over Current Protections Short Circuit/Over Current/Over Heat Protections
USB Charge IN Yes Yes Yes No
USB OUT 5V 1.5A 5V 1A No 5V 2.5A X2
Regulated OUT Three Regulated Outputs
3.3V 1A;5V 1.5V;9V/12V 0.5A
One Regulated Output
5V 1A
One Regulated Output
3.3V 90mA
Two Outputs
5V 5A; 12V 8A
Dimension 78.0mm×68.0mm 33.0mm×63.0mm 30.0mm×30.0mm 68.0mm×68.0mm
Features A complete multifunction solar power management module.
Applications: Small Solar Street Lamp, Solar Powered Robots
For 9V/12V/18V Solar Panels within 20W
A small and easy-to-use 5V solar power management module.
Applications: Solar Power Bank, Solar Environment Monitors
For 5V Solar Panels within 10W
A micro power solar power management module for low-power sensors and controllers.
Applications: Wireless Sensor Network, BLE iBecon
For 1V/2V/3V Solar Panels within 0.5W
Medium power solar management module for 12V lead-acid batteries.
Applications: Street lighting, intelligent agriculture, environmental monitoring station
For 18V Solar Panels within 100W


Solar Power Manager For 12V Lead-Acid Battery is a medium-power high-efficiency solar power management module, which is able to charge a 12V lead-acid battery with a maximum of 4A using a standard 18V solar panel. It is suitable for applications within 100W, such as 12V lighting equipments, security monitoring, small robots, pumps or environmental monitoring stations. It features as MPPT(Maximum Power Point Tracking) function, maximizing the output power of solar panels under various sunlight. Compared with common PWM solar controllers, it can improve charging performance by 10%-30%. Benefited from its small size and light weight, it is easy to embed it in your projects. The module provides dual high-power outputs 5V 5A (OUT1) and 12V 8A (OUT2) and dual USB outputs 5V 2.5A (USB1/USB2). Except USB1, all outputs can be turned ON/OFF by I/O pins of most controllers (3.3V/5V compatible). This feature helps to dynamically power loads and reduce power consumption. Various protection functions are also employed to ensure the safety and stability of the solar systems.



Attention Note 1:OUT1/USB1/USB2 shared 5A current driving capacity (peak current 8A), that is, the total output power of the three outputs should not exceed 5V*5A=25W (peak 40W).

Note 2: It does not guarantee support for all mobile phone or tablet PC. Please consult the device manufacturers or retailers for detail. If the mobile phone or tablet does not support the above USB charging protocol, the device usually limits the charging power to 5V*1A=5W for security. This is not caused by the failure of the USB output or insufficient output capability.


Board Overview

Quick Start

Build a solar powered system

Detailed Description

Maximum Power Point Tracking, MPPT

The MPPT (Maximum Power Point Tracking) can ensure the solar panel output power maintains at its maximum under different loads and sunlight, maximizing the conversion efficiency.

We can identify the short circuit current ISC and the open circuit voltage VOC from the cross points of the I/V curve (green) with x and y axis respectively. The ISC and VOC grow larger with the illumination increasing. With the output voltage VPANEL growing, the output current IPANEL gradually decreases and then jumps down after crosses a special point VMP, the maximum power voltage. By multiplying the voltage and current, which obviously results in power, and take the output voltage as the x axis, we obtain the P/V curve (blue). The output power PPANEL reaches its peak when the output voltage is at VMP. Although the maximum power increases with illumination, the VMP changes little. Therefore, we may approximately take the VMP as a constant for a specific solar panel under different illumination. This value is usually 70%~80% of the open circuit voltage VOC, i.e. VMP=(70% ~ 80%)*VOC.

The CN3767 solar power management IC employed in this module uses a constant voltage MPPT algorithm to control the solar output voltage around 18V to maximize the output power of the 18V solar panel. Compared with PWM solar controller, it can increase the output power of the solar panel by 10%-30%.

Charging Cycle

The module safely and quickly charges lithium battery through three phases: trickle charge, constant current charge, constant voltage charge.

Solar Panel Selection

The SOLAR IN port can be connected to standard solar panel with a nominal voltage of 18V. Taking into account the size, weight, price of the solar panel and the maximum charging current of the module, a solar panel with a rated power no more than 100W is recommended.

Battery Selection

This module adopts the four-stage charging mode for lead-acid batteries. The voltage in constant voltage stage is 14.8V, and the voltage in the float charging stage is 13.55V. Although the BAT IN port can be connected to the 12V lead-acid battery, such batteries have many subdivision types

The specific parameters of these batteries are not all the same. Users should pay attention to two parameters of the battery: float use voltage range and cycle use voltage range. 13.55V should be within the float use range and 14.8V should be within the cycle use range. If the battery does not indicate these parameters, please consult the battery manufacturer or retailers.

warning_yellow.png Warning

  • Do not use this module for other types of batteries except for 12V lead acid batteries.
  • Do not use the battery if the above battery parameters do not match the module charging voltage or if you are not sure about the parameters of the battery.

Muti-controllable Outputs

The module has two high-power outputs (OUT1=5V 5A, OUT2=12V 8A) and two USB outputs (USB1=5V 2.5A, USB2=5V 2.5A). Among them, OUT1/USB1/USB2 share the 5A current (peak current 8A), that is, the total output power of these three outputs should NOT exceed 5V*5A=25W (peak 40W). If only one of the OUT1/USB1/USB2 output is used alone, each output has a 5V 5A output capability (ie, if USB1 is used alone, it can continuously output 5V 5A; if USB2 is used alone, it can also output 5V 5A) . When USB1 is powered on, it cannot be turned off and has no output indicator. Users can use jumpers or I/O pins to control the ON/OFF of OUT1/OUT2/USB2. Insert the jumper into ON of the blue header. The corresponding output will be turned on (the green indicator turns on), and will be turned off when inserted into OFF header. Pull out the jumper and connect any digital I/O pin and GND to the pins on blue header labeled EN and GND (OUT1 corresponds to EN1, OUT2 corresponds to EN2, USB2 corresponds to ENU). Set the I/O pin to HIGH to turned on the output. Set to LOW to turned off. This feature is especially useful in water pumps, solar street lights or smart agriculture, which dynamically switch lighting or pumps depending on ambient light or soil moisture.


  • GND1 and GND2 are not the same as the system ground GND. When the OUT1 or OUT2 output is turned on, the corresponding GND1 or GND2 is connected to the system ground GND, respectively. When OUT1 or OUT2 output is turned off, GND1 and GND2 are left floating (disconnected from GND).
  • The 5V pin on each blue header has only 100mA drive capability. This pin unconditionally output 5V regardless of the protection mode (such as over current protection or over discharge protection). It is not recommended to drive device with this pin.

LED Indicators

There are four types of LED indicators indicating the operation status of different parts of the module:

Capacity Red(E) Yellow(25%) Green(50%) Blue(75%)
Power>75% ON ON ON ON
50%<Power≤75% ON ON ON OFF
25%<Power≤50% ON ON OFF OFF
Power≤25% ON OFF OFF OFF
Empty (Over-discharge Protection) OFF OFF OFF OFF

Protection Functions

pinMode(pin_EN2, OUTPUT);
digitalWrite(pin_EN2, HIGH);  //Set to HIGH to turn OUT2 on
pinMode(pin_EN2, INPUT);    //Set as INPUT (high-z) to float EN2 pin. OUT2 will remain on and enter protection mode

Heat Dissipation Enhancement

Although the cooling fin attached to the module can effectively enhance the heat dissipation during high current charging and discharging, when the module needs to work in hot outdoor or full load for a long time, its lifespan may be shortened due to long time operation in high temperature. Excessive temperature can also lower the over-current trigger threshold of OUT2, or even cause OUT1/USB1/USB2 to turn off due to thermal protection. If the module needs to run in such high temperature or high load condition for a long time, it is recommended that users use the common low-power silent cooling fan (commonly used in PC) to enhance the heat dissipation to extend the module’s life-span and improve its stability.

Application Examples

Use an AC Adapter to Charge a 12V Lead-acid Battery

It is possible to use this module to charge a 12V lead-acid battery at 4A with ''' a notebook AC adapter (usually rated 19V or 20V ) rated power no less than 65W ''' . Switch the MPPT to OFF to disable MPPT function. Connect the output of the AC adapter to the female DC power jack adapter and wire the SOLAR IN to the terminal end of the adapter (as shown followed).

Drive Multiple Motors with Romeo

When using Romeo to build a robotic, in order to drive multiple servos or high-power DC motors, you usually need a power adapter with a external power supply, a Lipo battery, or even a 12V lead-acid battery. With the module's powerful output capability, it can easily drive six servos and two additional DC motors, while providing a full range of protection for the battery. When the power is exhausted, it can also be charged by the power adapter. (Of course, solar panels can also be used to build solar-powered robots or trolleys), which is ideally suited as an embedded power management module for various types of systems driven by 12V batteries.

Build a UPS for Mini PC

Common Mini PCs such as Raspberry Pi, Latte Panda, or various ARM core-based development boards are widely used for various projects. In some projects, the mini PC may be part of a small server or security monitoring system. For such applications, the unexpected power outage of the power grid may cause the failure of the whole network. The Traditional UPS solution is large and cumbersome, and the cost is relatively high. However, many commercial power bank cannot charge (5V IN) the battery while discharge (5V OUT) at the same time. Also, they cannot power all 12V devices (such as routers, DTUs, security cameras). Thus they are not suitable as a UPS in these applications. With this module, a small UPS can be built. When the external power supply is interrupted unexpectedly, the module automatically switches to the battery power supply to provide continuous power supply to the system to avoid power failure.


For any questions, advice or cool ideas to share, please visit the DFRobot Forum.

Version iteration record

V2.0 Optimize the peripheral circuit design of CN1185, and solve the problem that the MOS tube may heat up abnormally when OUT2 is in use.

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