SPECIALTY CONCEPTS Mark III/ 20
SC3
(
Photovoltaic Battery Charge Controller
Installation & Operation Manual
20
/
)
SPECIALTY CONCEPTS, INC.
8954 Mason Ave.
Chatsworth, Ca 91311 USA
Copyright 5 / 1997 Specialty Concepts, Inc.
GENERAL DESCRIPTION
The Specialty Concepts Mark III/20 (SC3/20) is a battery charge controller and system monitoring
unit designed for use in mobile or stationary photovoltaic (PV) energy systems. This controller is
designed to be used with standard lead acid batteries that are normally supplied for use in stand
alone or mobile applications.
The SC3/20 uses a solid state pulse-type charge controller to safely reach and maintain a full
state of charge for the battery. A blocking diode is provided to eliminate losses through the solar
panels (array) at night. A digital meter is included for battery voltage, solar charge current, charge
set-point calibration, and a position for an external shunt (supplied separately) to read an
additional current. The fuse provides over-current and reverse polarity protection. "Charging",
“Charged”, and “Low Voltage” lights indicate battery state. This model is available for 12 volt
systems with charging currents up to 20 amps. The SC3/20 can be mounted flush or an additional
knockout box (4x7 BOX) can be purchased for wall mounting.
SPECIFICATIONS
PARAMETERS UNITS VALUE
Nominal Voltage (Volts) 12
Short Circuit Current, Continuous (Amps) 20
Short Circuit Current, Max (60 seconds) (Amps) 26
Load Current, Continuous (1)(3) (Amps) 10
Load Current, Max (60 seconds) (1)(3)(5) (Amps) 13
Array Voltage, Max Voc (Volts) 26
Operating Voltage @ Battery, Min. ( Charging) (Volts) 0
Operating Voltage @ Battery, Min. ( LVD )(1) (Volts) 8.5
Operating Voltage @ Battery, Min. ( Meter ) (Volts) 10
Quiescent Current (Milliamps) 15
Current Consumption, Charging, Typ. (Milliamps) 25
Current Consumption,
Load Disconnected, Typ. (1)(4) (Milliamps) 40
Voltage Drop, Array to Battery, Typ. (Volts) .40
Voltage Drop, Battery to Load, Typ. (1) (Volts) @ 10 amps .06
Charge Termination, Factory Set (Volts) 14.3 + .2
Charge Termination, Adjustable Range (6) (Volts) 13.8 to 14.9
Charge Resumption, Factory Set (7) (Volts) 13.0 + .3
Low Battery Warning Light, On (Volts) 11.7 + .3
Load Disconnect (LVD) (1) (Volts) 11.5 + .2
Load Reconnect (1) (Volts) 13.0 + .3
Meter Accuracy, DC current (int. shunt) 2 %
Meter Accuracy, DC current (ext. shunt) 1 %
Meter Accuracy, DC voltage 1 %
Operating Temp. Range (°C) 0 to 50
Storage Temp. Range (°C) -20 to 70
Temperature Comp. Coef. (from 25°C) (2) (Volts/°C) -.03
Notes: (1) Low-voltage Load Disconnect Option
(2) Temperature Compensation Option
(3) Non-inductive.
(4) LVD relay energized, red L.E.D. on, typical value.
(5) Carry only, Non-switching
(6) Set-points can be adjusted beyond this range but are not recommended
(7) The charge termination / reconnect span is fixed. Reconnect set-point changes during
charge termination set-point adjustment.
PART NUMBERING KEY
EXAMPLE: Nominal Voltage
SC3/20 - 12 - A
NOMINAL
MODEL VOLTAGE OPTIONS
SC3/20 12 A - Temperature Compensation
E - Low Voltage Disconnect (LVD)
ACCESSORIES
Model
Option
4x7 BOX
Specifications and product availability subject to change without notice.
SC3/ 20 FEATURES
CHARGE REGULATION
• 20 amp charge current, 12 volt
• Switching shunt, pulse charging
• Adjustable charging set-points
• Temperature compensation (option)
LOW VOLTAGE LOAD DISCONNECT (LVD)
(option)
• 10 amp LVD Relay
DESIGN FEATURES
• 100% solid state charge control
• Designed for rugged mobile use
• Over-current protection - Battery fuse
• Reverse leakage protection - Blocking diode
• Reverse polarity protection
• Lightning protection
• Input noise suppression
• Low power consumption
MONITORING
• Efficient Liquid Crystal Display (LCD)
-Measures battery voltage
-Measures charging current
-Measures second current with external
shunt (external shunt supplied
separately)
-Indicates charging set-point
• Charging light
• Charged light
• Low Voltage light
MOUNTING OPTIONS
• Flush mount
• Knock-out box available for wall mounting
(4x7 BOX accessory)
RELATED SYSTEM EQUIPMENT
The SC3/20 is an integral part of a solar electric power system that includes a PV solar array,
a battery and a load. These items should be installed in accordance with the National
Electrical Code, and with the instructions provided by the equipment supplier.
SOLAR ARRAY PANELS: The SC3/20 is compatible with all makes and models of PV panels,
provided the open circuit voltage (Voc) does not exceed 26 volts and the short circuit
current (Isc) of the array does not exceed 20 amps.
BATTERIES: The SC3/20 is calibrated for proper charging of standard batteries that are
normally used in recreational vehicles, boats, and remote stand alone systems. These
include wet cell batteries (with filler caps) and the sealed, maintenance-free batteries. A
battery disconnect switch should be installed on the Battery (+) run to the controller. This
will allow a safe way to disconnect the battery during installation.
TWO-BATTERY SYSTEMS & SYSTEMS WITH BATTERY ISOLATORS : If solar charging
of two separate batteries is desired, a switch can be installed to allow manual selection of
one battery or the other. In installations that use a diode battery isolator with two batteries,
the SC3/20 can be connected to one of the outputs from the isolator, or at one of the
batteries itself to charge that battery only. Do not connect the SC3/20 to the input of the
isolator, the SC3/20 will not operate properly when charging batteries through a diode.
LOADS: System loads such as lights, radios and DC/AC inverters must be 12 volts DC (unless
an inverter is being used). The loads should be fused as recommended and connected
directly to the battery or to a load center/circuit breaker box. See the diagrams in the
"INSTALLATION" section.
OTHER CHARGING SOURCES: The SC3/20 can be used only as a photovoltaic (solar)
charge controller. DO NOT use the SC3/20 to regulate other power sources , such as a
hydro or wind generator/alternator or an AC battery charger. This could result in damage to
the SC3/20 and/or the generating equipment
The SC3/20 CAN remain connected to a battery that is also being charged by an another
source (alternator, battery charger, etc.) without damage to the SC3/20 or to the solar
panels. Connect all other charging sources, with their own charge regulation devices,
directly to the battery. No isolation diode or transfer switch is required. NOTE: Some
battery chargers or converters powered by 110 volt sources are not properly regulated and
can overcharge batteries if left unattended.
INSTALLATION
WARNINGS / CAUTIONS
WARNING: Electricity, even low voltage electricity, can be dangerous. Installation should
be performed by a licensed electrical contractor or other qualified personnel only. The
requirements of the U.S. National Electrical Code should be followed.
WARNING: Follow all safety precautions of the battery manufacturer. Proper ventilation
must be provided for the batteries. Most batteries produce hydrogen gas when
charging, which is extremely explosive. Provide adequate battery ventilation. DO NOT
expose the battery to open flame, matches, cigarettes or sparks.
WARNING: Install properly DC rated, high interrupt, current limiting, over-current
protection and disconnect equipment between the SC3/20 and the battery. Suitable
fused disconnect switches are low cost and provide protection from fire and damage
due to over-current. Refer to the current National Electrical Code or your local
alternative energy vendor for recommendations.
CAUTION: DO NOT reverse battery "PLUS" and "MINUS" connections to the SC3/20.
Reverse polarity or accidental contact to the battery in reverse polarity will cause the
fuse to blow, and may damage the unit.
CAUTION: DO NOT connect the array directly to the battery when the array is connected
to the SC3/20 at the same time. This will cause damage to the SC3/20 when the battery
reaches full charge voltage.
CAUTION: DO NOT wire the SC3/20 in such a way that it can be connected to an
alternator (or other charging source) while the battery is disconnected, even if
momentarily. Other charging sources should have independent connections to the
battery.
INSTALLATION INSTRUCTIONS:
1. MOUNTING CONSIDERATIONS: - The SC3/20 is designed to be mounted flush against a
wall. It can be mounted onto a wall by adding the optional knockout box (4x7 BOX). Flush
mounting or wall mounting require different installation and mounting considerations.
FLUSH MOUNT: The flush mounted unit requires a rectangular cut-out in the mounting
surface with sufficient space (2-3 inches) immediately behind to accommodate the
controller. Electrical connection is made to the back of the controller via wires.
WALL MOUNT: The wall mounted unit (SC3/20 with the 4x7 BOX) is installed onto a wall
surface via four mounting screws. Electrical connections are made through knockouts
in the box to the wires on the back of the controller.
2. ACQUIRE TOOLS AND MATERIALS
TOOLS AND MATERIALS NEEDED:
FLUSH MOUNT:
Slotted screwdriver
Wire cutter/strippers
Drill with 3/32" and 3/8" bits
Keyhole saw or saber saw
Pencil, scratch awl or other marker
Soldering iron and solder (if available)
Electrical tape
Wire of sufficient gauge to run from the panels, to the SC3/20, and to the battery
(See WIRING INSTRUCTIONS: WIRE SIZE)
Mounting fasteners of appropriate type for wall material (3/4 - #6 screws provided)
Included are wire nuts, four 3/4 - #6 screws and washers, a spare fuse and a
spare programming jumper.
External shunt (if needed). Refer to “EXTERNAL SHUNT FOR 2ND CURRENT
READING”
WALL MOUNT (SC3/20 with 4X7 BOX):
Slotted screwdriver
Wire cutter/strippers
Pencil, scratch awl or other marker
Soldering iron, solder (if available)
Electrical tape
Wire of sufficient gauge to run from the panels, to the SC3/20, and to the battery
(See WIRING INSTRUCTIONS: WIRE SIZE)
Mounting fasteners of appropriate type to mount the box to the wall
1/2 inch Romex strain relief clamps
Included are wire nuts, four 3/4 - #6 screws and washers, a spare fuse and a spare
programming jumper.
External shunt (if needed). Refer to “EXTERNAL SHUNT FOR 2ND CURRENT
READING”
3. LOCATION: - The SC3/20 should be mounted where it can be easily seen and reached to take
the best advantage of the metering. Carefully consider how the wires are to be run from the
solar panel to the controller, and from the controller to the battery. The SC3/20 should be
mounted as close to the battery as possible, and should be mounted on a vertical surface to
aid in cooling.
FLUSH MOUNT: The SC3/20 is designed to be recessed into the side of a cabinet or wall
where the wiring can be accessed from the back. Allow 2 - 3 inches behind the unit.
WALL MOUNT: The SC3/20 with 4x7 BOX is designed to be mounted on the surface of a
cabinet or wall. Wiring can be run down the wall or through a hole in the wall directly below
the controller.
4. PROTECTION REQUIREMENTS: - The unit should be mounted indoors, out of the weather,
unless a weatherproof enclosure is used. Avoid mounting in direct sunlight or in a hot
environment. Basically, do not mount anywhere you would not put a TV or stereo.
5. PREPARE THE LOCATION PRIOR TO WIRING:
FLUSH MOUNT: Use the template provided to position and mark the cut-out and the four
mounting holes. Make the cut-out using a key hole or jig saw. Start by drilling holes in the
corners, then saw between the holes.
WALL MOUNT: Mount the knock-out box to the wall using suitable fasteners.
6. COMPLETE THE INSTALLATION OF PANEL, BATTERIES AND LOAD: - Follow the
manufacturer's instructions for mounting and wiring the solar panel, batteries and the load.
7. SELECT WIRE:
WIRE TYPE: - It is recommended that stranded wire rather than solid wire be used
whenever possible, because stranded wire does not fatigue and cause loose
connections over time as easily as solid wire does.
WIRE SIZE: - Wire should be sized of sufficient gauge to safely handle the rated current of
the system and to limit voltage drop. The wiring used within the controller is of sufficient
gauge to handle the currents carried, and these wires are short enough that voltage
drops are not a concern, but larger gauge may be appropriate for runs to the array or
battery.
Recommended Wire Size: # Solar Panels (50 watt) Minimum Wire Gauge
1 # 14
2 # 12
3 - 6 # 10
8. REMOVE POWER FROM BATTERY / PANELS: - Disconnect power from the batteries and
panels prior to running the wires to the controller.
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