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Morningstar SunSaver Duo SSD-25 > 25 Amp 12 Volt PWM Charge Controller

Morningstar SunSaver Duo SSD-25 > 25 Amp 12 Volt PWM Charge Controller

Our Price: $98.00
Warranty: 5 Years


Description Datasheet

Morningstar SunSaver Duo > 25 Amp 12 Volt PWM Charge Controller

Options: None (Remote meter not included)
Manufacturer Part Number: SSD-25

Morningstar’s SunSaver Duo (SSD-25) is an advanced PWM two battery controller for RV’s, caravans, boats and cottages. This product will charge two separate and isolated batteries at the same time, such as a “house” and an engine battery, based on user selectable priorities.

The SunSaver Duo employs Morningstar’s legendary SunSaver controller technology, whose long-term track record for high reliability and improved battery charging is well-recognized in the solar industry. The SunSaver Duo is epoxy encapsulated for environmental protection, is user adjustable via DIP switch or connection to a personal computer, and has an optional remote temperature sensor.

This unit does not include the remote meter accessory. To purchase the SSD-25 with a remote meter, see the SSD-25RM. To purchase the remote meter separately, see the RM-1.


Two Battery Charging

Solar charge current is shared between the two batteries based on a user selectable priority. When one battery is fully charged, all of the charge current flows to the other battery.

Provides Useful Information

The remote meter and LED’s display system status data and any system errors. Custom icons and back lighting make the meter easy to read and understand. The remote meter is not included with the SSD-25; the meter must be purchased separately.

Lower Cost

Two battery charging eliminates the added cost of two separate solar charging systems and the need for isolation between the batteries.

Easy to Install

The controller is installed near the batteries using the clearly labeled large wire terminals. The remote meter may be mounted in the wall or on the wall using the included frame. Also includes the meter wiring with RJ-11 connector.

Longer Battery Life

Four stage series PWM pulse charging and temperature compensation increases the useful life of the batteries.

Extensive Electronic Protections

The controller will not be damaged by wiring mistakes during installation. There are no fuses to replace, and the controller will automatically re-set after a wiring mistake.

Highly Reliable

Epoxy encapsulation protects the controller against dust and high humidity. Efficient electronics and a conservative thermal design allow the controller to operate reliably at high temperatures. Five year warranty and estimated 15 year life.


Rated Solar Input 25 amps
Rated Load Output Not applicable
Battery Voltage 12 volts
Min. Battery Voltage 1 volt
Max. Battery Voltage 15 volts
Max. Solar Voltage 30 volts
Self ConsumptionController 6 to 10 milliamps
Remote meter 6 to 15 milliamps
Remote MeterNot IncludedIncluded


  • Operating Ambient Temperature Controller –40°C to +45°C / –40°F to +113°F

    Meter –20°C to +60°C / –4°F to +140°F
  • Humidity 100% non-condensing
  • Tropicalization Controller Epoxy encapsulation

    Anodized aluminum case

    Corrosion resistant terminals

    Meter Conformal coated printed circuit board

Meter Displays

Backlighting Push button activated
LED’s Charging status
Battery level
Displays Battery #1 & #2 voltage
Battery charge priority
Minimum / maximum voltages
Solar charging amps / amp-hours

Electronic Protections

  • Solar Short Circuit
  • High Temperature
  • Solar Over Current
  • Lightning
  • Reverse Polarity
  • Reverse Current at Night

Battery Charging

The SunSaver Duo charges both sealed and flooded lead-acid batteries per the charging specifications in table 1 below. Sealed batteries are typically maintenance-free batteries that do not require water. Flooded batteries have removable caps that allow the addition of water when needed. DIP switches 1 & 2 select the battery type for Battery #1 and Battery #2 respectively. Choose the correct battery type for each battery.

DIP Switch OFF: Sealed battery type (factory pre-set)
DIP Switch ON: Flooded battery type
  • Regulation Voltage Sealed Battery 14.1 volts (at 25°C, 77°F)

    Flooded Battery 14.4 volts (at 25°C, 77°F)
  • Float Voltage 13.7 volts
  • Equalization Voltage* 14.8 volts
  • Temp. Compensation –30 millivolts per °C (25°C reference)
  • Type of Charging Series PWM

    4 stage: bulk, PWM, float, and equalize*

    *used on flooded battery only
  • Battery Charging Priority 90% / 10%

    50% / 50%

    Customize via PC connection


  • Controller: 17.0 x 5.6 x 4.1 cm / 6.7 x 2.2 x 1.6 in.
  • Meter: 9.7 x 9.7 x 3.1 cm / 3.8 x 3.8 x 1.2 in.
  • Meter back: 7.4 cm / 2.9 in. diameter

    2.8 cm / 1.1 in. deep

    Fits 7.6 cm / 3 in. round hole
  • Weight: Controller 260 g / 0.57 lb

    Meter 135 g / 0.30 lb
  • Largest wire: 16 mm2 (#6 AWG)
  • Meter wire: 10 m / 33 ft


  • Remote Temperature Sensor — Measures temperature at battery for improved battery charging


  • CE Compliant
  • Manufactured in a certified ISO 9001 facility

Warranty: Five year warranty period. Contact Morningstar for complete terms.

Detailed Description

Features Diagram

The major features of the SunSaver Duo are shown below. An explanation of each feature is provided.

SunSaver Duo

  • Remote Temperature Sensor (RTS) Terminals

    A connection point for a Morningstar RTS (optional) to remotely monitor battery temperature.

  • Local Temperature Sensor

    Measures ambient temperature. Battery regulation is adjusted accordingly.

  • Status LED Indicator

    Provides system status and error indication.

  • Settings DIP Switches

    Adjustment switches that define the operating parameters of the SunSaver Duo.

  • Battery #1 Power Terminals

    Power connections for battery #1.

  • Solar Input Power Terminals

    Power connections for solar module(s).

  • Battery #2 Power Terminals

    Power wire connections for battery #2.

  • Remote Meter Connection (RJ-11)

    A communication port for the Morningstar Remote Meter.

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