6 | SAMLEX AMERICA INC.
SeCtIOn 2 |
Features of the SCC-1208l
delivers a constant current equal to the
Short Circuit Current Isc of the Solar Panel.
The voltage seen at the output of the con-
troller will be the actual battery voltage
which will keep on rising till it approaches
the Absorption / Gassing Voltage of
14.8 V +/- 0.2 V for Flooded Battery and
14.5 V +/- 0.2 V for Sealed AGM battery
(at 25° C). The Absorption / Gassing Volt-
age is the voltage at which the electrolyte
in the battery begins to break down into
Hydrogen and Oxygen gases. On reaching
the Absorption Voltage, the controller will
transition to the Absorption Stage. The
bulk stage restores about 80% of the
battery’s capacity.
noteS:
As the bulk Charge Stage is a constant
current stage, the controller does not
control the voltage and the voltage seen
at the output terminals of the controller
will be the actual battery voltage (this will
rise slowly towards the Absorption / Gas-
sing Voltage under the influence of the
constant charging current). Also, the con-
troller does not control the current and
the bulk Charging Current will be equal
to the Short Circuit Current Isc of the Solar
Panel. Constant current is ensured by the
constant current characteristic of the Solar
Panel in the region of up to 15 V.
!
cAUtion
As already pointed out above, when in
the Bulk charge Stage, the controller is
not able to control the value of the charg-
ing current. the Bulk charging current
will be equal to the Short circuit current
isc of the Solar Panel. Hence, it should
be ensured that the AH capacity of the
battery (at 20 Hr Discharge Rate) is more
than at least 10 times the Short circuit
current isc of the Solar Panel. For exam-
ple, if a 130 W Solar Panel with Short
circuit current isc of around 8 A is being
used, the AH capacity of the battery
should be > 80 AH.
Stage 2 – Absorption Stage
During the Absorption Stage, the control-
ler changes from a constant current to
constant voltage charging. The charging
voltage is held constant near the Gassing
Fig. 2.1 Solar Charging Stages
