SPECIALTY CONCEPTS MODEL 2
SC2
(
Photovoltaic Battery Charge Controller
Installation And Operation Manual
SPECIALTY CONCEPTS, INC.
8954 Mason Ave.
Chatsworth, CA 91311 USA
MODELS: SC2-12, SC2-24, SC2-36, SC2-48 Copyright 10 / 1997 Specialty Concepts, Inc.
)
GENERAL DESCRIPTION
The SPECIALTY CONCEPTS CHARGER MODEL 2 (SC2) is a versatile, industrial quality
charge controller for the efficient use of photovoltaic energy and the protection of expensive
batteries. It is available for 12, 24, 36, and 48 volt systems with models for 30 amps of charge
current (optional 50 amps available for 12 and 24 volt units).
The SC2 consists of a series-relay battery charge controller in a wall mount chassis and a
system status light. The “CHARGE MODE” light indicates the charging condition. The SC2 is
housed in an anodized aluminum chassis and has a terminal block that accepts up to 10
gauge wire. A terminal adapter kit is included to increase wire size to #6.
FEATURES
CHARGE REGULATION
• 30 amp charge current, 12, 24, 36 or 48 volt
• 50 amp charge current (option), 12 or 24 volt
• Two-step, series charging, 12 and 24 volt
• Single step, series charging, 36 and 48 volt
• Adjustable charging set-points (option)
• Temperature compensation (option)
DESIGN FEATURES
• Reverse polarity protection
• Reverse leakage protection
• Lightning protection
• Input noise suppression
• Remote battery voltage sense
MONITORING
• Charging light
• Analog volt/amp meters (option)
MOUNTING OPTIONS
• Indoor wall mount
• Outdoor enclosure available
(accessory)
SPECIFICATIONS
PARAMETERS UNITS NOMINAL VOLTAGES
12 v 24 v 36 v 48 v
Charge Current, Continuous (1) (Amps) 30 30 30 30
Charge Current, Max (60 seconds) (2) (Amps) 39 39 39 39
Load Current, Continuous (3) (Amps) 30 30 30 30
Load Current, Max (60 seconds) (2) (Amps) 39 39 39 39
Array Voltage, Max Voc (Volts) 22 44 66 88
Operating Voltage @ Battery, Minimum (Volts) 8.5 17.0 25.5 34.0
Quiescent Current (4) (Milliamps) 10 10 10 10
Current Consumption, Charging (5) (Milliamps) 160 160 80 80
Current Consumption, Meter, Typ. (7) (Milliamps) . 5 .5 .5 .5
Voltage Drop, Typ. (Array to Battery) (Volts @ Max rating) .15 .15 .15 .15
Full Charge Termination (6) (Volts) 14.8 + .2 29.6 + .4 44.4 + .6 59.2 + .8
Full Charge Resumption (Volts) 12.8 + .2 25.6 + .4 38.4 + .6 51.2 + .8
Float Voltage (Volts) 14.1 + .2 28.2 + .4 NA
NA
Float Current, Max (Amps) 3 1 NA NA
Temp. Comp. coef. (from 25°C) (8) (Volts/°C) -.03 -.06 -.09 -.12
Operating Temp. Range (°C) 0 to 50 0 to 50 0 to 50 0 to 50
Storage Temp. Range (°C) -55 to 85 -55 to 85 -55 to 85 -55 to 85
Notes:
(1) 50 amp option available.
(2) Carry only, Non-switching
(3) Non-inductive.
(4) Both relays unenergized, red L.E.D.s off, typical value.
(5) Charge relay energized, red L.E.D. on, typical value.
(6) Adjustable set-point is available. Refer to table.
PART NUMBERING KEY
EXAMPLE: Model
SC2 - 12 - AF
NOMINAL
MODEL VOLTAGE OPTIONS
SC2 12 A - Remote Temperature Compensation
24 F - Volt Meter / Amp Meter
36 P - 50 Amp charge current (12 & 24 volt)
48 T - Adjustable Full Charge Termination
Set-point
FULL CHARGE TERMINATION SET- POINTS
Controller SWITCH POSITIONS
Voltage A B C D
12 15.3 14.8 14.3 13.8
24 30.6 29.6 28.6 27.6
36 45.9 44.4 42.9 41.4
48 61.2 59.2 57.2 55.2
Nominal Voltage
Options
ACCESSORIES
INDOOR ENCLOSURE (NEMA 13)
OUTDOOR ENCLOSURE (NEMA 4X)
Specifications and product availability subject to change without notice.
RELATED SYSTEM EQUIPMENT
The SC2 charge controller is an integral part of a solar electric power system that includes a PV
solar array and a battery. These items should be installed according to the instructions provided
by the equipment supplier.
SOLAR ARRAY PANELS: The SC2 is compatible with all makes and models of PV panels,
provided the open circuit voltage and the maximum power current of the solar panel does not
exceed the maximum open circuit voltage (Array Voltage, Max Voc) and the maximum charge
current (Charge Current, Max) specifications for the SC2 being used.
HIGHER CHARGING CURRENTS : For arrays exceeding the maximum power current of the
SC2, the array can be divided into smaller parallel sub-arrays. A SC2 can be wired in parallel
to each sub-array, provided the sub-arrays do not exceed the rating of the individual SC2.
BATTERIES: The standard SC2 is designed to be used with the most common lead-acid
batteries. These are wet cell batteries using pure lead, lead antinomy and/or lead calcium
grids. The standard charging set-points should be adjusted when using sealed, maintenance
free batteries, or vented pocket plate nickel-cadmium batteries. This will maximize
performance and battery life. Adjustments in set-points may be made on SC2 models with the
Adjustable Set-Point option (option T). For these batteries, consult the battery manufacturer
for recommended set-points and refer to Table 1 (OPTIONS section) for appropriate settings.
LOADS: The load is considered the item or equipment that the PV system is powering. System
loads such as lights, radios, DC/AC inverters, etc. must be rated for the proper DC input
voltage. DC loads not exceeding the rated SC2 load current (see SPECIFICATION section)
can be connected to the load terminals of the SC2, which provides an additional connection to
battery plus and minus for convenience. Higher current, or inductive loads such as pumps,
motors or inverters should be connected directly to the battery, using properly rated overcurrent protection devices (fuses or circuit breakers).
OTHER CHARGING SOURCES: Do not use the SC2 to regulate a power source other than a
solar panel, such as a hydro or wind generator/alternator or an AC battery charger. This could
result in damage to the SC2 and/or the generating equipment. Connect other charging
sources with their own regulation devices directly to the battery, using properly rated overcurrent protection devices.
The SC2 and solar panel can remain connected to a battery being charged by other sources,
(alternator, battery charger, etc.) without damage to the control or solar panel.
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. It is
recommended that the requirements of all applicable local electrical codes (or U.S. National
Electrical Code in the absence of local codes) be followed.
WARNING: Follow all safety precautions of the battery manufacturer and the National Electrical
Code. Proper ventilation must be provided for vented batteries. Most vented batteries produce
hydrogen gas when charging, which is extremely explosive. 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 SC2 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 subject the regulator to voltages greater than the "Array Voltage, Max Voc"
as stated in the SC2 specifications. This is the open circuit voltage (Voc) of the solar panel, or
the sum of the open circuit voltages of all modules connected in series.
CAUTION: DO NOT exceed the maximum current rating "Charge Current, Max" of the SC2
regulator as stated in the specifications. This is the sum of the maximum power currents of all
the modules in parallel.
CAUTION: On higher voltage units (36, 48 volt), exercise extreme care during installation. These
voltages can be extremely dangerous in that they can create large arcs, which can burn or
cause other injuries.
INSTALLATION INSTRUCTIONS:
1. LOCATION: - A suitable location must be found for mounting the SC2. The unit should be
mounted on a vertical surface and be as close as possible to the batteries to avoid errors in
battery voltage reading. DO NOT block the ventilation holes on the top and bottom of the SC2.
On units with the temperature compensation option, the sensor wire is 10 feet long and should
reach the battery bank if possible. For installation details on temperature compensation, refer
to options section.
2. PROTECTION REQUIREMENTS: - The unit should not be placed in direct sunlight or close to
any heat generating source to avoid extreme temperature increases. It must receive adequate
protection from rain, dust and bugs. The SC2 is NOT designed to be mounted outdoors or in
high humidity environments unless protected by a suitable enclosure.
3. MOUNT THE SC2: - Secure the SC2 to the selected location using the four mounting holes on
the chassis and proper fasteners.
4. COMPLETE THE INSTALLATION OF THE PANELS, BATTERIES AND LOAD: - Follow the
manufacturer's instructions for mounting and wiring the solar panel, batteries and the load.
5. 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: - The SC2 terminal block accepts bare wire up to 10 AWG, with a terminal
adapters included for up to 6 AWG. Wire should be sized of sufficient gauge to safely
handle the rated current of the system and to limit voltage drop. Consult wire sizing
tables and local alternative energy system suppliers for information on wire sizing.
6. REMOVE POWER FROM BATTERY / PANELS: - Disconnect power from the batteries and
panels prior to running the wires to the SC2 to prevent accidental damage or bodily harm.
7. RUN SYSTEM WIRING: - After disconnecting the power sources, refer to wiring diagram
(FIGURE 1) and run the system wiring to the location of the SC2. The wires should reach the
location of the SC2 with a little extra for strain relief loops.
8. NOTE WIRE POLARITY: - Insure that the polarity of the wires is correctly marked, using
colored wires or tags. Incorrect polarity should not damage the SC2, but incorrect operation
would result.
9. COMPLETE ARRAY AND BATTERY CONNECTIONS: - Connections to the SC2 terminal
block should be made with just the bare wire (not crimped spade or ring lugs unless the lugs
are crimped AND soldered).
10. COMPLETE LOAD CONNECTIONS: - DC loads not exceeding 30 amps can be connected
to the load terminals of the SC2. Higher current, or inductive loads such as pumps, motors or
inverters should be connected directly to the battery, using properly rated over-current
protection devices (fuses or circuit breakers).
11. BATTERY VOLTAGE SENSE CONNECTIONS: - The factory has installed two jumpers onto
Step 8 Battery Sense(+)( # 1): To Battery (+) (Remove #1-#2 jumper)
the terminal block. They connect the "BATTERY VOLTAGE SENSE" (positive and negative)
terminal to their respective "BATTERY" terminals. These jumpers should remain in place if
the SC2 is located within 5-10 feet of the batteries and if large enough wire is used to
minimize voltage drops to less than 2%.
If the SC2 is at a greater distance from the batteries and/or if the voltage drop in the
battery wires exceeds 2%, then the jumpers should be removed and replaced with another
circuit running directly to the battery terminals. This is a low current, voltage sensing circuit
that can be wired in 16 AWG wire. Proper over-current protection should be added on the
positive side. This connection will allow the SC2 to accurately measure battery voltage.
12. INSTALL FUSING AS NEEDED: - Add circuit protection where needed. A 30 amp fuse
(or 50 amp with P-Option) should be installed on the Battery (+) run of the SC2.
13. INSTALL TEMPERATURE COMPENSATION (option A): - If included. Refer to OPTIONS
section below.
14. MAKE ADJUSTMENT TO VOLTAGE SET-POINT (option T): - If included and if needed.
Refer to OPTIONS section below.
15. RECONNECT BATTERY AND ARRAY POWER
POWER CONNECT SEQUENCE
It is recommended that the power is supplied to the system using this
sequence. Some of the circuits within the SC2 must be reset to their "start
state" and this is automatically accomplished if the power is supplied in this
order. If the order is not followed, a period of up to 24 hours may have to
elapse before the electronics are fully reset.
Step 1 Battery (-) (terminal # 7): To Battery (-)
Step 2 Battery (+)( # 2): To Battery (+)
Step 3 Array (-)( # 6): To Solar Panel Array (-)
Step 4 Array (+)( # 3): To Solar Panel Array (+)
Optional (see “COMPLETE LOAD CONNECTIONS” above)
Step 5 Load Connect (-)( # 5): To Load (-)
Step 6 Load Connect (+)( # 4): To Load (+)
If Needed (see “BATTERY VOLTAGE SENSE CONNECTIONS” above)
Step 7 Battery Sense(-) ( # 8): To Battery (-). (Remove #7-#8 jumper)
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