Specialty Concepts SC2 - Manual (Page 9)

O P E R A T I O N
The SC2 uses a two-step control circuit to regulate the charging of storage batteries by
monitoring battery and array voltage. The charge regulator is fully automatic, and there are no
user adjustment or operations to perform. If the controller is supplied with the adjustable set-
point option (T option), the charge termination set-point may be adjusted.
REVERSE CURRENT PROTECTION - The SC2 is designed to minimize losses from the battery
at night. About 12 hours after sunrise the charging relay will open (stop charging), and stay
open if the battery stays above the reconnect threshold. If the battery goes below the
threshold and voltage is still available from the array, the relay will re-close (resume charging)
, and open again every 2 hours to determine if power is still available for charging. When no
charge is available (night time) the relay will remain open until sunrise. This guarantees that
the relay will be open every night, preventing reverse leakage current without cycling the relay
during the high current part of the day or using an inefficient blocking diode.
M O N I T O R I N G
CHARGE MODE LIGHT OFF (NIGHT TIME): All indicator lights will be off during periods when
no charging current is available (outside darkness). At night, the charging relay will be
opened, preventing reverse leakage current.
CHARGE MODE LIGHT ON: The "CHARGE MODE" light will be on when the controller is in the
full charge (constant current) mode. This mode is the primary charging step. In this mode,
the charging relay is closed, connecting the solar panel directly to the battery. Generally, this
light should go on in the morning at sunrise. All available output from the panels is channeled
into the battery bank. This light should stay on during daylight hours until the batteries have
been charged and the battery voltage has reached the "Full Charge Termination" set-point.
The light may go on again if the battery drops below the reconnect voltage ("Full Charge
Resumption") and the controller goes into the full charge mode again. It is not uncommon for
the light to remain on for several hours after dark.
CHARGE MODE LIGHT OFF (DAY TIME) (12 & 24 v units): The "CHARGE MODE" light will
go off when the controller is in the float mode. This is the secondary charging step. This
happens once the batteries have been charged and the battery voltage has reached the Full
Charge Termination set-point and voltage is still available from the array. Upon full-charge
termination, the voltage will generally instantly drop down below the "Float Voltage" set-point.
When the battery voltage is lower than the "Float Voltage" level, the control will supply the
batteries a small amount of current ("Float Current") in order for the batteries to reach and
maintain full charge. The level of float current is usually not sufficient to maintain the battery
voltage all the way up to the float voltage, and the battery will hover around 13.0-13.6 volts (or
26.0 - 27.2 )
During float charging, it is normal for the unit to feel warm. This is due to power dissipation
of the voltage regulated float circuit.