Samlexpower SCC-1208L Manuel Du Propriétaire page 6

SECTION 2 |
Stage 1 – Constant Current Bulk Charging Stage
In this stage, the MOSFET Switch is in "on" condition continuously till the next Absorp-
tion Stage voltage is reached. As the MOSFET switch is in "on" condition continuously, the
Solar Panel is connected to the battery continuously and it delivers a continuous current
equal to the Short Circuit Current "Isc" of the Solar Panel (Refer to Section 3.1 for more
details). The voltage seen at the output of the controller will be the actual battery volt-
age which will keep on rising till it approaches the Absorption / Gassing Voltage of 14.8
V +/- 0.2V for Flooded Battery and 14.5V +/- 0.2V for Sealed AGM battery (at 25°C). The
Absorption / Gassing Voltage 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 / Gassing Voltage under the
influence of the constant charging current). Also, the controller 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 15V.
!
CAUTION!
As already pointed out above, when in the Bulk Charge Stage, the controller
is not able to control the value of the charging current. The Bulk Charging Cur-
rent 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 example, 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 controller changes from a constant current to constant
voltage charging. The charging voltage is held constant near the Gassing Voltage to
ensure that the battery is further charged to the full capacity without overcharging.
The Absorption Stage restores the balance 20% of the capacity. As the output voltage
of the controller is held constant, the battery absorbs the charge slowly and the current
reduces gradually till all of the soft Lead Sulfate (PbSO
Lead Dioxide (PbO
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In SCC-1208L, the Absorption Stage is a constant voltage stage of 14.8V +/- 0.2V for
Flooded Battery and 14.5 V +/- 0.2 V for Sealed AGM battery (at 25°C). The current
from the Solar Panel is fed to the battery not continuously but in pulses of varying
pulse width at frequency of 30 Hz. This technique allows the current to be effectively
6 | SAMLEX AMERICA INC.
Description & Principles of Operation
) on the Positive Plates and Sponge Lead (Pb) on the Negative Plates.
) crystals have been converted to
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