Samlex Solar SCC-30AB Owner's Manual page 25

Stage - 1: Bulk Stage. During night, the battery voltage will drop below the Float
Transition Voltage Set Point "Vf" (Curve portion A to B), as there is no sun and
discharging takes place due to loads that are powered during the night e.g. night
lighting.
When the sun is available in the morning, charging commences in Bulk Stage.
During this stage (Curve portion B to C), the Switch is kept at 100% Duty Cycle (ON
continuously) and hence, maximum current equal to the available Short Circuit
Current "Isc" of the panel is fed to the battery and the battery voltage starts rising.
This is equivalent to Constant Current Charging. When the voltage reaches the
Absorption Regulation Voltage Set Point "Va" (Point "C") and is sustained for a
minimum period of around 50 to 55 sec, the controller transitions to Absorption Stage.
At the end of the Bulk Stage, the battery is charged to around 80% capacity. The
balance of 20% capacity is restored in the next Absorption Stage.
During this stage, the LCD Screen 4 (Fig 5.3) shows "State: Bulk". Screen 1 (Fig 5.3)
shows the actual terminal voltage of the battery under "BatV". This voltage will be
less than the programmed Absorption Voltage Set Point displayed on Screen 5 (Fig 5.3)
under "Bulk".
The Status LED will blink GREEN. The number of blinks indicates battery voltage levels
as follows:
No. of Voltage Level for 12V Battery (x 2 for 24V Battery) with respect to
Blinks Absorption Transition Voltage Set Point "Va"
1 > 0.75V below Absorption Voltage Regulation Set Point "Va"
2 0.75V below Absorption Voltage Regulation Set Point "Va"
3 0.5V below Absorption Voltage Regulation Set Point "Va"
4 0.25V below Absorption Voltage Regulation Set Point "Va"
Stage - 2: Absorption Stage. The controller enters this stage at Point "C" from
the previous Bulk Stage when the battery voltage reaches the Absorption Voltage
Regulation Set Point "Va" and is sustained for a minimum period of around 50 to 55 sec.
This stage is timed for 1 Hr - either continuous or cumulative (Curve Portion C to D).
In this stage, the Switch operates under PWM control by feeding pulsing Short Circuit
Current "I " with constantly reducing Duty Cycle (< 100% and > 0%) / average current
SC
to keep the battery voltage constant at the Absorption Voltage Regulation Set Point
"Va" (Curve portion C to D). This is equivalent to Constant Voltage Charging. This is an
intentional, controlled over voltage condition for the battery for 1 Hr. This is necessary
to return the balance 20% of the capacity. At this voltage, the battery starts gassing
PRINCIPLE OF OPERATION & FEATuREs
BLINkING PATTERN OF "STATUS LED – BULk STAGE
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