Morningstar SUNSAVER DUO User manual

DUAL BATTERY CHARGING SOLAR CONTROLLER
FOR RVS, CARAVANS, AND BOATS
RÉGULATEUR DE CHARGE SOLAIRE POUR DEUX BATTERIES
POUR CAMPING-CARS, CARAVANES ET BATEAUX
SOLARLADEREGLER FÜR ZWEI BATTERIEN
FÜR WOHNMOBILE, WOHNWAGEN UND BOOTE
REGULADOR SOLAR DE CARGA DUAL
PARA VEHÍCULOS RECREATIVOS, AUTOCARAVANAS Y BARCOS
SOLAR CONTROLLER
S
UN
S
AVER
D
UO
TM
For a more detailed manual, please see our website.
Pour une version plus détaillée s’il vous plaît consulter notre site Web.
Für eine detailliertere Version finden Sie auf unserer Website.
Para obtener una versión más detallada por favor visite nuestro sitio web.
InstallatIon and operatIon Manual ...2
Manuel d’InstallatIon et d’utIlIsatIon ...20
BedIenungs- und InstallatIonsanleItung ...38
Manual de InstalacIón yoperacIón ...58
www.morningstarcorp.com

2
SUNSAVER DUO DIMENSIONS
1.36
34.52
6.65
168.78
6.10
154.94
2.17
55.12 1.00 25.4
0.28
7.24
inches (mm)
Ratings
• Nominal Voltage 12 Volts
• Rated Solar Current 25 Amps

ENGLISH
3
IMPORTANT SAFETY INFORMATION
SAVE THESE INSTRUCTIONS:
This manual contains important safety, installation and operating
instructions for the SunSaver Duo solar controller.
The following symbols are used throughout this manual to indicate
potentially dangerous conditions or important safety instructions.
WARNING: Indicates a potentially dangerous condition.
Use extreme caution when performing this task.
CAUTION: Indicates a critical procedure for safe and proper
operation of the controller.
NOTE: Indicates a procedure or function that is important for
the safe and proper operation of the controller.
The major features of the SunSaver Duo are shown in figure 1 below.
An explanation of each feature is provided.
6
The major features of the SunSaver Duo are shown in figure 1 below. An explanation of
each feature is provided.
Figure 1. SunSaver Duo features
R em ote Tem peratu re Sensor (RTS) T e rm inals
A connection point for a Morningstar RTS (optional) to remotely monitor battery
temperature.
Local Tem peratu re S ensor
Measures ambient temperature. Battery regulation is adjusted accordingly.
Status LED Indicato r
Provides system status and error indication.
Settings DIP Sw itches
Adjustment switches that define the operating parameters of the SunSaver Duo.
B atte ry #1 P o w e r T e rm inals
Power connections for battery #1.
Sola r Input P o w e r T e rm inals
Power connections for solar module(s).
B atte ry #2 P o w e r T e rm inals
Power wire connections for battery #2.
R em ote M ete r C onnection (R J-11)
A communication port for the Morningstar Remote Meter.
Figure 1. SunSaver Duo features
Remote Temperature Sensor (RTS) Terminals
A connection point for a Morningstar RTS (optional) to remotely monitor
battery temperature.

4
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.
Morningstar Accessories
Remote Temperature Sensor (Model: RTS)
The RTS measures battery temperature for accurate temperature com-
pensation. Use when the ambient battery temperature differs from the
ambient controller temperature by +/– 5 degrees C or more.
Remote Meter (Model: RM-1)
The digital Remote Meter displays system operating information, error
indications, and self-diagnostic read-out.
PC MeterBus Adapter (Model: MSC)
The MSC converts the MeterBus RJ-11 electrical interface to a standard
RS-232 interface which allows communication between the SunSaver
Duo and a PC. The MSC is required for programming custom charging
setpoints and for logging data. Visit Morningstar’s website for more
information.

INSTALLATION
General Installation Notes
• Read through the entire installation section before beginning
installation.
• Be very careful when working with batteries. Wear eye protection.
Have fresh water available to wash and clean any contact with
battery acid.
• Use insulated tools and avoid placing metal objects near the
batteries.
• Explosive battery gasses may be present during charging. Be certain
there is sufficient ventilation to release the gasses.
• Do not install in locations where water can enter the controller.
• Loose power connections and/or corroded wires can melt wire
insulation, burn surrounding materials, or even cause fire. Ensure
tight connections and use cable clamps to secure cables in mobile
applications.
• Only charge lead-acid batteries.
• Each of the two SunSaver Duo Battery connections may be wired to
one battery or a bank of batteries. The following instructions refer to
a singular battery, but it shall be implied that each battery connection
can be made to either one battery or a group of batteries wired in
parallel to form a 12 volt battery bank.
Adjusting DIP Switches
9
3.2 Adjusting DIP Switches
Figure 2. Setting DIP switch definitions
DIP Sw itches 1 & 2 – B atte ry Type S elect
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
B atte ry Type
Setpoint S ealed Flooded
Absorption Voltage 14.1 V 14.4 V
Float Voltage 13.7 V 13.7 V
Boost Voltage X 14.8 V
Boost Time X 2 hrs
Boost Interval X 28 days
Table 1. Standard battery charging programs
DIP Sw itch 3 – B attery C harging P rio rity
Select the percentage of available charge current to each battery.
Figure 2. Setting DIP switch definitions
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5

6
DIP Switches 1 & 2 – Battery Type Select
The SunSaver Duo charges both sealed and flooded lead-acid batteries
per the charging specifications in table 1 below.
DIP Switch OFF: Sealed battery type (factory pre-set)
DIP Switch ON: Flooded battery type
BATTERY TYPE
Setpoint Sealed Flooded
Absorption Voltage 14.1 V 14.4 V
Float Voltage 13.7 V 13.7 V
Boost Voltage X14.8 V
Boost Time X2 hrs
Boost Interval X28 days
Table 1. Standard battery charging programs
DIP Switch 3 – Battery Charging Priority
Select the percentage of available charge current to each battery.
DIP Switch 3 OFF: 90% / 10% Priority (factory pre-set)
DIP Switch 3 ON: 50% / 50% Priority
DIP Switch 4 – Custom Setpoints
If the standard battery type settings are not suitable, custom charging
setpoints can be programmed using a PC and a Morningstar Serial to
Meterbus adapter (not included). See Morningstar’s website for more
information.
DIP Switch 4 OFF: Factory settings (factory pre-set)
DIP Switch 4 ON: Custom programmed settings
DIP Switch 5 – Regulation Type
The SunSaver Duo is a PWM charge controller. Some systems with
sensitive equipment may experience noise interference from PWM
charging. Refer to the FAQ in Troubleshooting for tips on how to
reduce or eliminate PWM noise.
If the noise cannot be satisfactorily reduced, place DIP switch 5 in
the ON position. While less efficient, Slow Switching regulation will
significantly reduce or eliminate PWM noise.
DIP Switch 5 OFF: PWM Regulation (factory pre-set)
DIP Switch 5 ON: Slow Switching Regulation

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7
Mounting
NOTE: When mounting the SunSaver Duo, ensure free air
flow through the controller heat sink fins. There should be
at least 3 inches (75 mm) clearance above and below the
controller to allow for cooling. If mounted in an enclosure,
ventilation is highly recommended.
WARNING: Never install the SunSaver Duo in a sealed
enclosure with vented (flooded) batteries! Do not install in
a confined area where battery gasses can accumulate.
RISK OF EXPLOSION!
1. Locate the SunSaver Duo on a vertical surface protected from direct
sun, high temperatures, and water.
2. Place the SunSaver Duo in the location where it will be mounted.
Verify that there is sufficient room to run wires and that there is
ample room above and below the controller for air flow.
11
3.3 M ounting
NO TE: When mounting the SunSaver Duo, ensure free air flow through the controller
heat sink fins. There should be at least 3 inches (75 mm) clearance above and below
the controller to allow for cooling. If mounted in an enclosure, ventilation is highly
recommended.
W ARNING: Never install the SunSaver Duo in a sealed enclosure with vented
(flooded) batteries! Do not install in a confined area where battery gasses can
accumulate. Risk of explosion!
1. Locate the SunSaver Duo on a vertical surface protected from direct sun, high
temperatures, and water.
2. Place the SunSaver Duo in the location where it will be mounted. Verify that
there is sufficient room to run wires and that there is ample room above and
below the controller for air flow.
Figure 3. Mounting and cooling
3. Use a pencil or pen to mark the four (4) mounting hole locations on the mounting
surface.
4. Remove the controller and drill 3/32” (2.5 mm) holes in the marked locations.
5. Place the controller on the surface and align the mounting holes with the drilled
holes in step 4. Secure the controller in place using the mounting screws
(included).
Figure 3. Mounting and cooling
3. Use a pencil or pen to mark the four (4) mounting hole locations on
the mounting surface.
4. Remove the controller and drill 3/32” (2.5 mm) holes in the marked
locations.
5. Place the controller on the surface and align the mounting holes with
the drilled holes in step 4. Secure the controller in place using the
mounting screws (included).

8
Wiring
Three system wiring examples are provided for RV’s and caravans,
boats, and non-mobile installations. Reference the appropriate wiring
diagram for your installation.
CAUTION: Protect system wiring from sharp edges and foot
traffic. Use grommets and wire loom where necessary.
NOTE: Power connection order is not critical. A connection
order has been provided for each installation type for
instructional purposes only.
NOTE: Wiring charts on page 17 of this manual provide
minimum recommended wire size.
RV / CARAVAN INSTALLATION
A wire jumper is installed across the Remote Temperature
Sensor (RTS) terminals at the factory. The jumper can
prevent false RTS detection due to condensation on the
SunSaver Duo. Do not remove this jumper unless an
optional RTS is to be installed.
12
3.4 Wiring
Three system wiring examples are provided for RV’s and caravans, boats, and non-
mobile installations. Reference the appropriate wiring diagram for your installation.
CAUTION:Protect system wiring from sharp edges and foot traffic. Use grommets and
wire loom where necessary.
NO TE:Power connection order is not critical. A connection order has been provided
for each installation type for instructional purposes only.
NO TE: Wiring charts on the back page of this manual provide minimum
recommended wire size.
RV /CARAVAN IN STA LLA TION
Figure 4. Typical RV / Caravan wiring diagram
NO TE:To ensure good vehicle chassis ground connections:
- remove all paint, grease, debris at grounding point.
- use sandpaper/emory cloth to expose chassis bare metal.
- use ring terminal and star- or lock-washer to secure cable.
- dielectric grease can be used to minimize corrosion.
Before proceeding, mount the solar module(s) per the manufacturer’s instructions. If
adding batteries that are not factory installed, they should be safely secured in their
desired location. The SunSaver Duo should be mounted per the instructions in section
2.3 M ounting.
Figure 4. Typical RV / Caravan wiring diagram

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9
NOTE: To ensure good vehicle chassis ground connections:
• remove all paint, grease, debris at grounding point.
• use sandpaper/emery cloth to expose chassis bare metal.
• use ring terminal and star- or lock-washer to secure cable.
• dielectric grease can be used to minimize corrosion.
Before proceeding, mount the solar module(s) per the manufacturer’s
instructions. If adding batteries that are not factory installed, they
should be safely secured in their desired location. The SunSaver Duo
should be mounted per the instructions in section Mounting.
Step 1: Ground SunSaver Duo
Ground a negative terminal of the SunSaver Duo to the vehicle
chassis. The SunSaver Duo has a common negative; it does not matter
which negative terminal is grounded. Use wire with black insulation,
appropriately sized for the system charging current (see page 17).
Step 2: Battery #1 (“house” battery bank)
Connect Battery #1 to the SunSaver Duo as shown in figure 4. In RV
installations, Battery #1 should be the “house” or cabin battery.
If the cabin battery was factory installed, battery negative should
already be grounded to the vehicle chassis. Use a short piece of black
wire to ground the cabin battery if necessary. Use red wire for battery
positive. Use wire appropriately sized for the system charging current
(see back page).
An in-line fuse holder should be wired in the positive line no further
than 12” (305 mm) from the battery post. Do not insert a fuse in the
fuse holder at this time.
Step 3: Battery #2 (engine battery)
Connect Battery #2 to the SunSaver Duo as shown in figure 4. The
engine battery should already be grounded to the vehicle chassis. Use
red wire for battery positive. Use wire appropriately sized for the system
charging current (see page 17).
An in-line fuse holder should be wired in the positive line no further
than 12” (305 mm) from the battery post. Do not insert a fuse in the
fuse holder at this time.
Step 4: Solar
Ground the solar module(s) to the vehicle chassis with black wire.
Multiple 12V nominal solar modules may be wired together in parallel
and grounded with one wire. Use red wire for the solar positive connec-
tion to the SunSaver Duo. Use wire appropriately sized for the system
charging current (see page 17).

10
Confirm that the solar modules are wired for 12V nominal output before
connecting them to the SunSaver Duo. In full sun, the output voltage of
the solar modules should be 18 – 25 Volts before connection to the
SunSaver Duo.
Upon connection of the Solar positive wire, the SunSaver Duo should
begin the start-up sequence, flashing the Status LED 3 times.
Step 5: Remote Temperature Sensor (optional)
An optional Remote Temperature Sensor (purchased separately) mea-
sures the temperature directly at the battery for more accurate battery
charging. Remove the wire jumper from the RTS terminals before install-
ing the sensor. The RTS includes full installation instructions.
Step 6: Insert Fuses
Insert a 30 A dc-rated fuse into the fuse holder in each of the battery
positive wires. If the solar module(s) is in full sun, charging should begin.
BOAT INSTALLATION
A wire jumper is installed across the Remote Temperature
Sensor (RTS) terminals at the factory. The jumper can
prevent false RTS detection due to condensation on the
SunSaver Duo. Do not remove this jumper unless an
optional RTS is to be installed.
WARNING: Only ground the DC system to battery negative
(one-point ground). Never ground the DC system to the boat
bonding system or to any metallic part, fixture, or component
on the boat.
NOTE: An existing common ground wire may connect the
negative battery terminals of two or more on-board batteries.
This cable will not interfere with the SunSaver Duo operation.

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11
14
BOAT IN STA LLA TION
W ARNING:Only ground the DC system to battery negative (one-point ground). Never
ground the DC system to the boat bonding system or to any metallic part, fixture, or
component on the boat.
NO TE:An existing common ground wire may connect the negative battery terminals
of two or more on-board batteries. This cable will not interfere with the SunSaver Duo
operation.
Figure 5. Typical boat wiring diagram
Before proceeding :
xInstall the solar module(s) per the manufacturer’s instructions.
xBatteries should be installed per the U.S Coast Guard regulations for
pleasureboats. The batteries must be secured to prevent movement and the
battery terminals covered to prevent arcing. A battery box to contain any
spilled battery acid is strongly recommended.
xThe SunSaver Duo should be mounted per the instructions in section 2.3
M ounting.
Step 1:B atte ry # 1 (“house” batte ry bank)
Wire the negative terminal of the “house” battery to the negative B attery 1
terminal on the SunSaver Duo with black wire as shown in figure 5. Wire the
“house” battery positive power cable as shown in figure 5. Wire a DC-rated in-line
fuse holder in the cable. The length of cable between the Battery (+) post and in-
line fuse holder should be no longer than 12” ( 305 mm ). Use wire with red
Figure 5. Typical boat wiring diagram
Before proceeding:
• Install the solar module(s) per the manufacturer’s instructions.
• Batteries should be installed per the U.S Coast Guard regulations for
pleasureboats. The batteries must be secured to prevent movement
and the battery terminals covered to prevent arcing. A battery box to
contain any spilled battery acid is strongly recommended.
• The SunSaver Duo should be mounted per the instructions in section
Mounting.
Step 1: Battery # 1 (“house” battery bank)
Wire the negative terminal of the “house” battery to the negative
Battery 1 terminal on the SunSaver Duo with black wire as shown in
figure 5. Wire the “house” battery positive power cable as shown in
figure 5. Wire a DC-rated in-line fuse holder in the cable. The length of
cable between the Battery (+) post and in-line fuse holder should be no
longer than 12” ( 305 mm ). Use wire with red insulation, appropriately
sized for the system charging current (see back page). Do not insert
a fuse in the fuse holder at this time.
Step 2: Battery # 2 (“house” battery)
Wire the negative terminal of the engine battery to the negative
Battery 1 terminal on the SunSaver Duo with black wire as shown in
figure 5. Wire the engine battery positive power cable as shown in fig-
ure 5. Wire a DC-rated in-line fuse holder in the cable. The length of
cable between the Battery (+) post and in-line fuse holder should be
no longer than 12” (305 mm). Use wire with red insulation, appropri-
ately sized for the system charging current. Do not insert a fuse in
the fuse holder at this time.

12
Step 3: Solar
Connect the solar module(s) output to the Solar input connection of the
SunSaver Duo. Multiple 12V nominal modules may be wired together in
parallel and wired to the SunSaver Duo with one pair of wires. Use red
wire for solar positive and black wire for solar negative.
Confirm that the modules are wired for 12V nominal output before
connecting them to the SunSaver Duo. Double-check polarity before
connection. In full sun, the output voltage of the solar modules should
be 18 – 25 Volts before connection to the SunSaver Duo.
Upon connection of the solar positive wire, the SunSaver Duo should
begin the start-up sequence, flashing the Status LED 3 times.
Step 4: Remote Temperature Sensor (optional)
An optional Remote Temperature Sensor (purchased separately) mea-
sures the temperature directly at the battery for more accurate battery
charging. Remove the wire jumper from the RTS terminals before install-
ing the sensor. The RTS includes full installation instructions.
Step 5: Insert Fuses
Insert a 30 A dc-rated fuse into the fuse holder in each of the battery
positive wires. If the solar module(s) is in full sun, charging should begin.
NON-MOBILE / PERMANENT DWELLING INSTALLATION
A wire jumper is installed across the Remote Temperature
Sensor (RTS) terminals at the factory. The jumper can
prevent false RTS detection due to condensation on the
SunSaver Duo. Do not remove this jumper unless an
optional RTS is to be installed.
16
NON-MOBILE / PERMANENT DWELLING INSTALLATION
+
-
+-+-
Battery
#2
Battery
#1
30A Fuse 30A Fuse
Solar PV
Array
Earth
Ground
Earth
Ground
Earth
Ground
Figure 6. Terrestrial wiring diagram
NOTE: Earth grounding is recommended but not required. Grounding helps protect
against lightning by providing a direct path to earth. In areas prone to frequent
lightning strikes, external lightning arrestors and/or other means of protection may be
needed.
NOTE: If a Remote temperature Sensor (RTS) is not used, inserting a jumper across
the RTS terminals can prevent false RTS detection due to condensation on the
SunSaver Duo. Secure a short piece of wire across the RTS terminals.
Step 1: Battery #1
Connect Battery #1 to the SunSaver Duo as shown in figure 6. If charging priority
is set to the default 90% / 10% setting, battery 1 will receive 90% priority. Use red
wire for battery positive and black for battery negative. An in-line fuse holder
should be wired in the positive line no further 12” ( 305 mm ) from the battery
post. Earth ground the battery negative post if desired using a short piece of
black wire appropriately sized for the system charging current (see back page).
Do not insert a fuse in the fuse holder at this time.
Step 3: Battery #2
Connect Battery #2 to the SunSaver Duo as shown in figure 6. Use red wire for
battery positive and black for battery negative. An in-line fuse holder should be
wired in the positive line no further 12” ( 305 mm ) from the battery post. Earth
ground the battery negative post if desired using a short piece of black wire
appropriately sized for the system charging current (see back page). Do not
insert a fuse in the fuse holder at this time.
Figure 6. Terrestrial wiring diagram

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1313
NOTE: Earth grounding is recommended but not required.
Grounding helps protect against lightning by providing a
direct path to earth. In areas prone to frequent lightning
strikes, external lightning arrestors and/or other means of
protection may be needed.
Step 1: Battery #1
Connect Battery #1 to the SunSaver Duo as shown in figure 6. If
charging priority is set to the default 90% / 10% setting, battery 1
will receive 90% priority. Use red wire for battery positive and black for
battery negative. An in-line fuse holder should be wired in the positive
line no further 12” ( 305 mm ) from the battery post. Earth ground the
battery negative post if desired using a short piece of black wire appro-
priately sized for the system charging current (see back page). Do not
insert a fuse in the fuse holder at this time.
Step 2: Battery #2
Connect Battery #2 to the SunSaver Duo as shown in figure 6. Use red
wire for battery positive and black for battery negative. An in-line fuse
holder should be wired in the positive line no further 12” (305 mm) from
the battery post. Earth ground the battery negative post if desired using a
short piece of black wire appropriately sized for the system charging cur-
rent (see page 17). Do not insert a fuse in the fuse holder at this time.
Step 3: Solar
Connect the solar module(s) output to the Solar input connection of the
SunSaver Duo. Multiple 12V nominal modules may be wired together in
parallel and wired to the SunSaver Duo with one pair of wires. Use
appropriately sized red wire for solar positive and black wire for solar
negative.
Confirm that the modules are wired for 12V nominal output before con-
necting them to the SunSaver Duo. Double-check polarity before con-
nection. In full sun, the output voltage of the solar modules should be
18 – 25 Volts before connection to the SunSaver Duo.
Upon connection of the Solar positive wire, the SunSaver Duo should
begin the start-up sequence, flashing the Status LED 3 times.
Earth ground solar negative if desired using a short piece of black wire
appropriately sized for the system charging current (see page 17).
Do not insert a fuse in the fuse holder at this time.
Step 4: Remote Temperature Sensor (optional)
An optional Remote Temperature Sensor (purchased separately) mea-
sures the temperature directly at the battery for more accurate battery
charging. Remove the wire jumper from the RTS terminals before install-
ing the sensor. The RTS includes full installation instructions.

14
Step 5: Insert Fuses
Insert a 30 A dc-rated fuse into the fuse holder in each of the battery
positive wires. If the solar module(s) is in full sun, charging should begin.
OPERATION
LED Indications
The Status LED indicates system operational state and any existing
error conditions. Table 1 below defines the Status LED indications.
Status LED Operating State
Off: 5 second
heartbeat
1
Night
Green: on solid
(5 second
heartbeat
2
)
Bulk Charging
Green: Flashing
3
Absorption, Float, or Equalize
Red: Flashing Error
Red: On solid
(5 second
heartbeat
2
)
Critical Error
Table 1. Status LED definitions
1heartbeat indication flickers the Status LED on briefly every 5 seconds
2heartbeat indication flickers the Status LED off briefly every 5 seconds
3Battery 1 and Battery 2 must both be in regulation
Red (flashing) Errors
• reverse polarity battery connection.
• reverse polarity solar connection.
• solar over-current condition.
• high temperature.
• damaged or disconnected Remote Temperature Sensor.
• high voltage disconnect.
Red (on solid) Critical Errors
• damaged local temperature sensor.
• damaged heatsink temperature sensor.
For more information on errors, see Protections section.

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15
Charging Information
19
4.2 Charging Information
The SunSaver Duo is an advanced, fully automatic solar battery charger. No
adjustments are required except to select the battery type at installation. Each battery is
charged independently. The SunSaver Duo has a 4-stage charging algorithm as shown
in figure 7.
NIGHT NIGHT
1
BULK
CHARGE
2
ABSORPTION
3
FLOAT
TIME
VOLTAGE
4
BOOST
Figure 7. SunSaver Duo charging algorithm
1. Bulk Charge – Recharging with 100% of available solar energy.
2. Absorption – PWM constant-voltage regulation to prevent heating and
excessive battery gassing. Pulse charging to restore full battery capacity.
3. Float – After battery is fully charged, SunSaver Duo reduces to a float or “trickle
charge”.
4. Boost (Flooded battery type only – Every 28 days) – A boost charge for flooded
batteries, bringing uneven cell voltages into balance and extending battery life.
Sometimes called an equalization charge.
NOTE: A 15V maximum battery voltage limit prevents damage to sensitive DC loads.
Figure 7. SunSaver Duo charging algorithm
1. Bulk Charge – Recharging with 100% of available solar energy.
2. Absorption – PWM constant-voltage regulation to prevent heating
and excessive battery gassing. Pulse charging to restore full battery
capacity.
3. Float – After battery is fully charged, SunSaver Duo reduces to a float
or “trickle charge”.
4. Boost (Flooded battery type only – Every 28 days) – A boost charge
for flooded batteries, bringing uneven cell voltages into balance and
extending battery life. Sometimes called an equalization charge.
NOTE: A 15V maximum battery voltage limit prevents
damage to sensitive DC loads.
Protections
Over-current – Solar charge current exceeds the current rating of the
SunSaver Duo. Automatically reconnects in 30 seconds.
CAUTION: A mis-wired connection of a battery to the Solar
input when a second battery is already connected to a
Battery input may damage the SunSaver Duo.
High Temperature – The heatsink temperature is above safe limits.
Automatically reconnects when heatsink cools to a safe temperature.
Short Circuit – Solar input power wires are short-circuited. Charging
automatically resumes when the error is cleared.
Battery Reverse Polarity – Battery 1 or Battery 2 power connections
are connected backwards. Error clears when the mis-wire is corrected.

16
Damaged Local Temperature Sensor – The local ambient temperature
sensor is short-circuited or damaged. Charging stops to avoid over- or
under-charging. This is a critical error.
Damaged Internal Temperature Sensor – The internal heatsink tem-
perature sensor reading is damaged. This is a critical error.
Remote Temperature Sensor (RTS) – A bad RTS connection or
severed RTS lead has disconnected the temperature sensor during
charging. Charging automatically resumes when the problem is fixed.
To resume operation without an RTS, disconnect all power to the
SunSaver Duo and then reconnect.
High Voltage Transients – Battery 1, Battery 2, and Solar input power
connections are protected against high voltage transients. In lightning
prone areas, additional external suppression is recommended.
Inspection and Maintenance
The following inspections and maintenance tasks are recommended at
least two times per year for best controller performance.
• Tighten all terminals. Inspect for loose, broken, or corroded
connections.
• Verify all wire clamps and tie-downs are secure.
• Check that the controller is mounted in a clean protected
environment free of dirt, insects, nests, and corrosion.
• Check enclosure ventilation and air flow holes for obstructions
if applicable.
• Verify LED indication is consistent with the system conditions at
that time.
• Verify that the Remote Temperature Sensor (if used) is securely
attached to the battery.
TECHNICAL SPECIFICATIONS
ELECTRICAL
• Nominal system voltage .............. 12 V
• Max. solar current ........................ 25 A
• Battery voltage range.................. 1 V – 15 V
• Max. solar voltage........................ 30 V
• Self-consumption .......................... 5.5 mA (night)
10.0 mA (charging)
• Accuracy
Voltage............................................ 1.0 %
Current ............................................ 2.0 %

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17
• Meterbus Connection................... 6-pin RJ-11
• Transient Surge Protection.......... 1500 Watts, all power connections
BATTERY CHARGING
• Regulation Method....................... 300 Hz PWM or
Slow Switching (10 Hz max.)
•
Temp. Compensation Coefficient .. –30 mV / °C (25°C reference)
• Temp. Compensation Range........ –30°C to + 60°C
• Temp. Compensated Setpoints ... Absorption, Float, Equalize
BATTERY SETPOINTS
Sealed Flooded
• Absorption .................................... 14.1 V 14.4 V
• Float............................................... 13.7 V 13.7 V
• Time until Float............................. 1 hr 1 hr
• Equalize ......................................... N/A 14.8 V
• Equalize Calendar ......................... N/A 28 days
• Maximum Regulation.................... 15.0 V 15.0 V
• High Voltage Disconnect ............. 15.5 V 15.5 V
• High Voltage Reconnect .............. 14.0 V 14.0 V
MECHANICAL
• Power terminals wire size (max.)
Solid ................................................ #6 AWG / 16 mm2
Multistrand ...................................... #6 AWG / 16 mm2
Fine strand ...................................... #8 AWG / 10 mm2
Terminal Diameter........................... 0.210 in / 5.4 mm
• Power terminals torque (max.).... 35 in-lb / 4 Nm
• RTS terminals wire size (max.)
Wire gauge (min)............................. #22 AWG / 0.3 mm2
Wire gauge (max)............................ #12 AWG / 3.0 mm2
• RTS terminals torque (max.) ........ 0.4 Nm / 3.5 in-lb
• Dimensions .................................... see page 17
ENVIRONMENTAL
• Operating temperature................ –40°C to +45°C
• Storage temperature.................... –40°C to +85°C
• Humidity........................................ 100% N.C.

18
Minimum Recommended Wire Gauge
Solar
Amps
One Way Wire Distance (feet)
Wire Gauge (AWG)
14 12 10 8 6
270 112 180 287 456
435 56 90 143 228
818 28 45 72 114
12 12 19 30 48 76
16 9 14 23 36 57
20 7 11 18 29 46
25 6 9 14 23 36
3% Voltage drop, Annealed Copper Wire at 20°C
One-way wire distance: Solar SunSaver Duo or
SunSaver Duo Battery
Solar
Amps
One Way Wire Distance (meters)
Wire Gauge (mm
2
)
2.0 3.0 5.0 8.0 13.0
221.3 34.1 54.9 87.5 139.0
410.7 17.1 27.4 43.6 69.5
85.5 8.5 13.7 21.9 34.7
12 3.7 5.8 9.1 14.6 23.2
16 2.7 4.3 7.0 11.0 17.4
20 2.1 3.4 5.5 8.8 14.0
25 1.8 2.7 4.3 7.0 11.0
3% Voltage drop, Annealed Copper Wire at 20°C
One-way wire distance: Solar SunSaver Duo or
SunSaver Duo Battery
Specifications subject to change without notice.
Designed in the U.S.A.
Assembled in Taiwan

20
DIMENSIONS DU SUNSAVER DUO
1.36
34.52
6.65
168.78
6.10
154.94
2.17
55.12 1.00 25.4
0.28
7.24
inches (mm)
Ratings
• Tension nominale 12 Volts
• Courant solaire nominal 25 A