Specialty Concepts SCS/90 - Manual (Page 12)

O P E R A T I O N
CHARGE REGULATION (12 and 24 volt units): The two-step control circuit regulates the
charging of storage batteries by monitoring battery and solar panel voltage. STEP 1:
CONSTANT CURRENT (FULL) CHARGE MODE: At sunrise, the charging relay energizes
and closes, connecting the solar panel directly to the battery and lighting the "CHARGE
MODE" light. The battery will accept as much current as the solar panel will provide, and
battery voltage will rise. STEP 2: CONSTANT VOLTAGE (FLOAT) CHARGE MODE:
When the battery reaches the full charge termination voltage, the charging relay will open
and the "CHARGE MODE" light will go out. At this point the float controller takes over to
keep the battery below the float voltage and supply limited current (maximum float current).
As the battery approaches the float voltage, the current will taper off, eventually falling to
the battery's maintenance current.
CHARGE REGULATION (36 and 48 volt units): The operation of a 36 and 48 volts unit is
identical with the exception that no float circuit is included.
MAXIMUM SOLAR PANEL USAGE : If a load is applied when the controller is in the float
mode, the controller will supply up to its maximum float current to maintain the battery
charge. If the load is less than the maximum float current the batteries will still be receiving
a net charge from the float controller. If the load current is more, the battery will supply
what the float controller cannot and the battery voltage will fall. When it falls below the full
charge resumption voltage, the charging relay will re-close, re-initiating the full charge
mode. This insures that if a large load is applied during the day, maximum use will be made
of the power available from the solar panel.
LOW-VOLTAGE DISCONNECT : The low-voltage disconnect (LVD) of the SCS prevents
damage from deep discharge of the batteries by automatically disconnecting the loads.
The disconnect threshold is load current compensated by a factor of 10 mv/amp, and a
minimum time of 3 seconds is applied to prevent false disconnect. When a disconnect
occurs, the load relay is energized and opens, and a red "LOAD DISCONNECTED" light,
visible on the front panel, will light to indicate that the loads have been disconnected.
Normal battery charging will continue. When the battery voltage rises to the reconnect
threshold, the loads will automatically be reconnected to the battery and the red light will go
off. The LVD function has a reset/disable switch and user adjustable set-points.
Note: The amount of time required to recharge the battery sufficiently to reconnect the
loads depends upon the battery size, solar panel current and weather conditions. In some
cases, it can take several days or longer. The loads can be manually reset prior to the
reconnect voltage by pressing the "MANUAL RESET" switch.
REVERSE CURRENT PROTECTION : The SCS uses a timing circuit to disconnect the solar
panel from the battery at night, preventing reverse leakage current loses through the solar
panel. About 12 hours after sunrise the charging relay will open. If the battery is below the
reconnect threshold and voltage is still available from the solar panel, the relay will re-close
and continue charging. It will open again about every 2 hours thereafter to determine if
power is still available for charging. The relay will stay open after the 12 hour period if the
battery is above the reconnect threshold or if there is no power available from the solar
panel. This results in the relay being open every night. Note: The relay may be closed
("CHARGING" light on) for a few hours in the evening after the sun has gone down.