BlueSolar PWM-DUO 20A Solar Charge Controller

☀️ BLUESOLAR PWM DUO LCD & USB 12/24V 20A SOLAR CHARGE CONTROLLER

20A Dual-Battery PWM Solar Controller – LCD Display, Two Battery Outputs, External Temperature Sensor & Dual 5V USB Charging

☀️ Manage solar charging for two separate battery banks with the BlueSolar PWM-DUO LCD-USB 12/24-20 Charge Controller – a versatile 20A PWM solar regulator designed for applications such as boats, motorhomes, caravans and other dual-battery systems.

The DUO controller can charge two separate batteries from the connected solar array, making it suitable for configurations such as a starter battery and a service or auxiliary battery. The charging-current ratio between the two battery outputs is programmable, allowing the available solar charge to be distributed according to the requirements of the installation.

A built-in LCD provides system monitoring and setup, while programmable charging algorithms support AGM, GEL, flooded lead-acid and LiFePO4 batteries with an internal BMS.

The controller also includes an external temperature sensor, two 5V USB outputs with a combined maximum output of 2A, three-stage charging, reverse-polarity protection and automatic 12V/24V system-voltage detection for applicable battery types.

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⚡ KEY FEATURES

🔋 Charges Two Separate Batteries
Two independent battery outputs allow solar charging of separate battery banks, such as a starter battery and a service or auxiliary battery.

⚖️ Programmable Charge Current Ratio
The charging-current ratio between the two battery outputs can be programmed to suit the required system configuration.

☀️ 20A Rated Charge Current
Supports a rated solar charge current of up to 20A.

🔋 Automatic 12V / 24V Detection
Automatically detects 12V or 24V system voltage for applicable battery types.

⚠️ Manual Voltage Selection for LiFePO4
Automatic system-voltage detection is not provided for LiFePO4 batteries according to the supplied specifications.

📟 Built-In LCD Display
Liquid crystal display provides convenient system-status monitoring and controller setup.

🌡️ External Temperature Sensor Included
A remote battery temperature sensor is supplied with the controller.

🔌 Two 5V USB Outputs
Provides two USB charging outlets with a combined maximum current of 2A.

⚙️ Programmable Battery Charging
Supports programmable charge algorithms for AGM, GEL, flooded lead-acid and suitable LiFePO4 batteries with an internal BMS.

🔄 Three-Stage Charging
Uses bulk, absorption and float charging stages, with programmable settings.

💡 Programmable Lighting Control
The supplied feature information includes a fully programmable lighting-control function.

🔌 Programmable Load Function
The supplied description includes low-voltage and manual disconnect functionality together with overload and short-circuit protection for the load function.

🛡️ Reverse-Polarity Protection
Designed with protection against reverse-polarity connection of the battery and/or solar panels.

🌡️ Over-Temperature Protection
Includes controller protection against excessive operating temperature.

🔩 Large 16mm² Terminals
Supports cable sizes up to approximately 16mm² / AWG6 at the specified terminals.

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🔋 DUAL-BATTERY SOLAR CHARGING

The key feature of the BlueSolar PWM DUO is its ability to charge two separate batteries from a solar installation.

A typical application could include:

• 🚗 Vehicle or boat starter battery
• 🔋 Auxiliary or service battery

This can simplify solar charging in systems where maintaining both a starting battery and a separate house or service battery is required.

The charge-current ratio between Battery 1 and Battery 2 is programmable, providing greater flexibility than a conventional single-output solar regulator.

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⚖️ PROGRAMMABLE CHARGE CURRENT RATIO

The DUO controller allows the available charge current to be distributed between its two battery outputs according to a programmable ratio.

This provides flexibility where one battery requires a greater share of the available solar charging than the other.

For example, a system may prioritise a larger service battery while still maintaining a separate starter battery.

⚠️ IMPORTANT: Configure the charge distribution and battery settings to suit the batteries and electrical system being used.

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📟 BUILT-IN LCD DISPLAY

The integrated liquid crystal display provides convenient controller monitoring and setup without requiring a separate display.

The supplied features describe the LCD as supporting:

• System status monitoring
• Controller setup
• Battery charging configuration
• Programmable operating functions

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🔄 THREE-STAGE BATTERY CHARGING

The BlueSolar PWM DUO uses a three-stage charging process:

• ⚡ Bulk
• 🔋 Absorption
• 🟢 Float

The charge parameters are programmable, allowing the controller to be configured for the supported battery type.

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🔋 AGM, GEL, FLOODED & LIFEPO4 BATTERY ALGORITHMS

The supplied product information lists programmable charging algorithms for:

• 🔋 AGM batteries
• 🔋 GEL batteries
• 🔋 Flooded lead-acid batteries
• 🔋 LiFePO4 batteries with an internal BMS

⚠️ IMPORTANT: LiFePO4 use is specified for batteries with an internal BMS. Always configure the charge controller according to the battery manufacturer’s charging requirements.

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⚠️ LIFEPO4 SYSTEM VOLTAGE NOTE

The controller normally provides automatic 12V/24V system-voltage detection.

However, the supplied specifications specifically state that automatic system-voltage detection does not apply to LiFePO4 operation.

⚠️ IMPORTANT: When using a compatible LiFePO4 battery, ensure the correct system voltage and charging configuration are selected as required rather than relying on automatic voltage detection.

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🌡️ EXTERNAL BATTERY TEMPERATURE SENSOR INCLUDED

A remote external battery temperature sensor is included with the BlueSolar PWM DUO.

The supplied temperature-compensation specifications are:

12V system: -30mV/°C

24V system: -60mV/°C

This allows the controller to account for battery temperature when applying applicable temperature-compensated charging parameters.

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⚡ DEFAULT ABSORPTION VOLTAGE

The supplied default absorption charging voltages are:

12V system: 14.4V

24V system: 28.8V

The supplied information notes that alternative voltage settings are available and should be referenced in the controller manual.

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🟢 DEFAULT FLOAT VOLTAGE

The supplied default float charging voltages are:

12V system: 13.7V

24V system: 27.4V

Alternative charging voltage settings are available according to the supplied documentation.

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🔌 TWO 5V USB CHARGING OUTPUTS

The controller includes two convenient 5V USB outputs.

Combined maximum USB output current: 2A

These outputs can provide convenient low-voltage USB power for compatible devices within the limits of the controller.

⚠️ IMPORTANT: The 2A rating is the combined maximum across both USB outputs, not 2A per USB port.

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💡 PROGRAMMABLE LIGHTING CONTROL

The supplied feature list includes a fully programmable lighting-control function.

This can provide additional flexibility in suitable solar installations requiring controlled operation of connected lighting or loads.

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🔌 LOAD CONTROL & LOW-VOLTAGE DISCONNECT

The supplied feature description lists programmable load control with low-voltage and manual disconnect capability.

An automatic load-disconnect voltage is also supplied:

12V system: Approximately 10.5V

24V system: Approximately 21V

The supplied feature information also states overload and short-circuit protection for the load output.

⚠️ SPECIFICATION NOTE: The detailed supplied specification table identifies the load output as “2 USB ports 5V/2A”, while the general product feature list separately describes programmable load and lighting functions. These supplied descriptions have been retained without assuming additional output-terminal specifications that were not provided.

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🛡️ REVERSE-POLARITY PROTECTION

The BlueSolar PWM DUO includes protection against reverse-polarity connection of the solar panels and/or battery according to the supplied information.

The detailed specifications identify battery reverse-polarity protection as fuse protected.

⚠️ IMPORTANT: Protection features should not be treated as a substitute for correct wiring. Always verify polarity before connecting the battery or solar array.

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🌡️ OVER-TEMPERATURE PROTECTION

Over-temperature protection is included as part of the controller’s supplied protection features.

The specified operating temperature range extends from approximately -35°C to +55°C at full load.

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☀️ SOLAR INPUT VOLTAGE

The supplied maximum solar voltages are:

12V system: Maximum approximately 28V

24V system: Maximum approximately 55V

⚠️ IMPORTANT: Do not exceed the controller’s maximum permitted solar input voltage.

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☀️ SOLAR PANEL CONFIGURATION

The supplied panel guidance states:

• For 12V systems – use 36-cell solar panels
• For 24V systems – use a 72-cell solar panel or 2 × 36-cell panels connected in series

⚠️ IMPORTANT: Confirm the complete solar-array electrical specifications, including open-circuit voltage, remain within the controller’s input limits under expected operating conditions.

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🔋 AUTOMATIC 12V / 24V SYSTEM DETECTION

The BlueSolar PWM-DUO LCD-USB 12/24-20 supports both 12V and 24V battery systems.

Automatic system-voltage detection is supplied for applicable battery configurations.

LiFePO4 operation is specifically excluded from automatic system-voltage detection in the supplied technical information.

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⚡ 20A RATED CHARGE CURRENT

The BlueSolar PWM DUO is rated for a maximum charge current of 20A.

This rating should be considered together with the connected solar-array voltage, battery-bank configuration, cable sizing and installation requirements.

⚠️ IMPORTANT: Do not exceed the controller’s rated 20A charging capacity.

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🔋 LOW CONTROLLER SELF-CONSUMPTION

The supplied controller self-consumption is approximately:

10mA

This helps minimise the controller’s own electrical demand while connected to the battery system.

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🔩 COMMON NEGATIVE GROUNDING

The supplied grounding configuration is common negative.

This should be considered when integrating the controller into an existing vehicle, boat, motorhome or other DC electrical system.

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🌡️ WIDE OPERATING TEMPERATURE RANGE

The supplied operating temperature range is:

Approximately -35°C to +55°C at full load

The controller is also specified for non-condensing humidity levels up to approximately 95%.

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💧 IP20 ENCLOSURE

The controller carries a supplied IP20 protection classification.

⚠️ IMPORTANT: IP20 does not indicate a waterproof enclosure. Install the controller in a suitable dry and protected location away from water, condensation and inappropriate environmental exposure.

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🔩 16MM² / AWG6 TERMINAL CAPACITY

The supplied terminal size is:

16mm² / AWG6

Use correctly sized conductors for the current, cable length and voltage-drop requirements of the complete solar charging installation.

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🚐 IDEAL FOR DUAL-BATTERY MOBILE SYSTEMS

The two-battery charging arrangement makes the BlueSolar PWM DUO particularly useful for compatible applications such as:

• 🚐 Motorhomes
• 🚐 Caravans
• 🚤 Boats
• 🚙 Vehicle dual-battery systems
• ⛺ Camper trailers
• 🛻 Touring vehicles
• 🔋 Starter + auxiliary battery systems
• ☀️ Small off-grid solar systems

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📏 COMPACT CONTROLLER DIMENSIONS

Height: Approximately 101.5mm

Width: Approximately 184.0mm

Depth: Approximately 47.1mm

Weight: Approximately 0.3kg

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📋 TECHNICAL SPECIFICATIONS

Product: BlueSolar PWM-DUO LCD-USB 12/24-20

Controller type: PWM solar charge controller

System voltage: 12V / 24V

System-voltage detection: Automatic for applicable battery types

LiFePO4 automatic voltage detection: No

Rated charge current: 20A

Separate battery outputs: 2

Programmable charge-current ratio: Yes

Display: Liquid crystal display

Battery temperature sensor: Yes – remote sensor included

Battery algorithms: AGM, GEL, flooded lead-acid and LiFePO4 with internal BMS

Charging stages: Bulk, absorption and float

Default absorption voltage – 12V system: 14.4V

Default absorption voltage – 24V system: 28.8V

Default float voltage – 12V system: 13.7V

Default float voltage – 24V system: 27.4V

Temperature compensation – 12V: -30mV/°C

Temperature compensation – 24V: -60mV/°C

USB outputs: 2 × 5V USB ports

Maximum combined USB output: 2A

Automatic load disconnect – 12V: Approximately 10.5V

Automatic load disconnect – 24V: Approximately 21V

Maximum solar voltage – 12V system: 28V

Maximum solar voltage – 24V system: 55V

Self-consumption: Approximately 10mA

Reverse-polarity protection: Yes

Battery reverse-polarity protection: Fuse

Over-temperature protection: Yes

Grounding: Common negative

Operating temperature: Approximately -35°C to +55°C at full load

Humidity: Maximum approximately 95%, non-condensing

Protection class: IP20

Maximum terminal size: 16mm² / AWG6

Dimensions: Approximately 101.5 × 184.0 × 47.1mm

Weight: Approximately 0.3kg

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📜 STANDARDS

Safety: IEC 62109-1

EMC: EN 61000-6-1

EMC: EN 61000-6-3

Automotive electrical transient standard: ISO 7637-2

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☀️ PANEL CONFIGURATION GUIDANCE

For a 12V installation, the supplied documentation specifies the use of a 36-cell solar panel.

For a 24V installation, the supplied documentation specifies either:

• 1 × 72-cell solar panel, or
• 2 × 36-cell solar panels connected in series

⚠️ IMPORTANT: Panel cell count alone is not a substitute for checking the panel’s electrical specifications. Ensure the completed array remains within the controller’s maximum permitted solar voltage.

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⚠️ INSTALLATION & BATTERY COMPATIBILITY

Before installing the BlueSolar PWM DUO, confirm that the complete solar, battery and wiring configuration falls within the supplied controller specifications.

Check the following:

• 12V or 24V battery-system voltage
• Battery chemistry
• Correct charging algorithm
• LiFePO4 battery has an internal BMS where applicable
• Correct manual system-voltage configuration for LiFePO4 where required
• Solar-array maximum voltage
• Solar charge current remains within the 20A controller rating
• Correct polarity before connection
• Suitable cable size
• Appropriate external circuit protection where required
• Correct terminal tightening and connection
• Suitable charge-current ratio between Battery 1 and Battery 2
• Correct location for the supplied temperature sensor
• Dry installation environment suitable for an IP20 enclosure
• Adequate airflow around the controller

⚠️ IMPORTANT: Incorrect battery settings can result in unsuitable charging. Configure the controller according to the battery manufacturer’s requirements.

⚠️ IMPORTANT: Do not connect a solar array that can exceed the controller’s specified 28V maximum on a 12V system or 55V maximum on a 24V system.

⚠️ IMPORTANT: This controller is IP20 and should be installed in a dry, protected location.

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❓ FREQUENTLY ASKED QUESTIONS

What is the BlueSolar PWM DUO LCD & USB controller?

It is a 20A PWM solar charge controller designed for 12V or 24V battery systems and capable of charging two separate batteries.

What is the model number?

The supplied model designation is BlueSolar PWM-DUO LCD-USB 12/24-20.

What does DUO mean?

The DUO configuration provides two separate battery outputs, allowing the solar system to charge two batteries.

Can it charge a starter battery and an auxiliary battery?

Yes. The supplied information specifically gives a starter battery and service battery in a boat or mobile home as an example application.

Can I control how the solar charge is divided between the batteries?

Yes. The charge-current ratio between the two battery outputs is programmable.

What is the maximum rated charging current?

The supplied rated charge current is 20A.

Does the controller work on 12V?

Yes. It supports 12V battery systems.

Does it work on 24V?

Yes. It also supports 24V systems.

Does it automatically detect 12V or 24V?

Yes, automatic system-voltage detection is supplied for applicable battery types.

Does automatic 12V/24V detection work with LiFePO4?

No. The supplied specifications specifically state that LiFePO4 does not use automatic system-voltage detection.

Can it charge LiFePO4 batteries?

Yes. The supplied charging algorithms include LiFePO4 batteries with an internal BMS.

Can it charge AGM batteries?

Yes. AGM charging algorithms are included.

Can it charge GEL batteries?

Yes. GEL charging algorithms are included.

Can it charge flooded lead-acid batteries?

Yes. Flooded lead-acid battery algorithms are included.

What charging stages does it use?

The controller uses bulk, absorption and float charging stages.

Can the charging settings be programmed?

Yes. The supplied product information describes the charging process and battery algorithm as programmable.

What is the default absorption voltage?

The supplied defaults are 14.4V for a 12V system and 28.8V for a 24V system.

What is the default float voltage?

The supplied defaults are 13.7V for a 12V system and 27.4V for a 24V system.

Can those voltages be changed?

Yes. The supplied documentation states that alternative voltage settings are available and refers users to the manual.

Does it have an LCD screen?

Yes. A built-in liquid crystal display is included for status monitoring and setup.

Does it include a battery temperature sensor?

Yes. A remote external battery temperature sensor is included.

What is the supplied temperature compensation?

The supplied values are -30mV/°C for a 12V system and -60mV/°C for a 24V system.

Does it have USB outputs?

Yes. Two 5V USB outputs are included.

How much current can the USB ports provide?

The two ports have a combined maximum output of approximately 2A.

Is that 2A per USB port?

No. The supplied specification states that 2A is the combined maximum current for both USB outputs.

Does it have a lighting-control function?

Yes. A fully programmable lighting-control function is included in the supplied feature information.

Does it have low-voltage load disconnect?

The supplied features include programmable low-voltage and manual load disconnect functionality.

What are the automatic disconnect voltages?

The supplied figures are approximately 10.5V for a 12V system and 21V for a 24V system.

Does it protect against load overload and short circuit?

Yes. Overload and short-circuit protection for the supplied load function are included in the feature description.

Why does the specification table call the load output the USB ports?

The supplied information contains both descriptions: the general feature list describes programmable load and lighting control, while the detailed specification table lists “2 USB ports 5V/2A” under load output. This listing retains both supplied statements without assuming additional terminal specifications that were not provided.

Does it have reverse-polarity protection?

Yes. The supplied information states that the controller is protected against reverse-polarity connection of the solar panels and/or battery.

Does it have over-temperature protection?

Yes. Over-temperature protection is listed in the supplied technical specifications.

What is the maximum solar voltage on a 12V system?

The supplied maximum is approximately 28V.

What is the maximum solar voltage on a 24V system?

The supplied maximum is approximately 55V.

What solar panel should I use on a 12V system?

The supplied guidance specifies a 36-cell solar panel for 12V operation.

What solar panel arrangement should I use on 24V?

The supplied guidance specifies either a 72-cell solar panel or two 36-cell panels connected in series.

How much power does the controller itself consume?

The supplied self-consumption figure is approximately 10mA.

Is the controller common-negative?

Yes. Common-negative grounding is specified.

What operating temperature range is specified?

The supplied operating range is approximately -35°C to +55°C at full load.

What humidity can it operate in?

The supplied specification lists a maximum of approximately 95% non-condensing humidity.

Is the controller waterproof?

No waterproof rating is supplied. The enclosure is rated IP20, so it should be installed in a suitable dry and protected location.

What size cable terminals does it have?

The supplied maximum terminal size is 16mm² / AWG6.

How large is the controller?

The supplied dimensions are approximately 101.5mm high × 184.0mm wide × 47.1mm deep.

How much does it weigh?

The supplied weight is approximately 0.3kg.

What standards are listed?

The supplied standards include IEC 62109-1 for safety and EN 61000-6-1, EN 61000-6-3 and ISO 7637-2 for applicable electromagnetic compatibility and electrical transient requirements.

Is this suitable for a boat?

Yes. The supplied product information specifically gives charging the starter and service batteries of a boat as an example of the dual-battery function. Installation must still be appropriate for the environment, particularly because the controller enclosure is IP20.

Is it suitable for a motorhome or caravan?

Yes. The two-battery charging configuration is suitable for compatible mobile-home, motorhome and caravan systems where the controller’s voltage, current and environmental specifications are appropriate.

What is the main advantage of the DUO version?

The key advantage is the ability to charge two separate battery banks while programming how the available solar charge current is distributed between them.

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☀️ SMART DUAL-BATTERY SOLAR CHARGING WITH LCD & USB CONTROL

Choose the BlueSolar PWM-DUO LCD-USB 12/24-20 when you need a straightforward 20A PWM controller capable of maintaining two separate battery banks from one compatible solar installation.

With programmable dual-battery charge distribution, AGM/GEL/flooded/LiFePO4 charging algorithms, three-stage charging, LCD monitoring, an included external temperature sensor and dual 5V USB outputs, it provides flexible solar charging for compatible boats, motorhomes, caravans and other auxiliary-battery systems.

Match the controller to the correct battery chemistry, solar voltage and system configuration for reliable 12V or 24V solar charging.