SamplexPower SEC-1250UL Mode D'emploi page 12

seCtIOn 4 |
StAGe 2 – ABSoRPtion StAGe ("U
During this stage, the charger outputs constant voltage of 14V / 14.4V for SEC-1250UL
and 28V / 28.8V for SEC-2440UL. As charging proceeds, there is a fairly sharp rise in the
battery voltage as gassing starts. Gassing and fast rise of battery voltage continues to
restore the balance of the capacity till charging is completed.
The Charger Transitions To Absorption Stage ("U
As soon as the charger transitions to this stage, a user selectable 4 Hr / 8 Hr Timer is
started with the help of DIP Switches (7) (See page 22 under "Selecting time for stage
2 - Absorption Stage"). This Timer decides the maximum duration of operation in this
stage and subsequent transition to the final constant voltage Float Stage 3 at point "E".
The duration of operation in this stage is also determined by another condition where
the transition to the next Float Stage at point "E" occurs when the charging current
reduces to 10% or the rated capacity i.e. 5A +/- 0.5A for SEC-1250UL and 3A +/- 0.5A for
SEC-1225UL. The condition, which occurs earlier, controls the transition
At the transition point "C", the charger will output a higher constant voltage, which is
above the Gassing Voltage to ensure that the battery is further, charged to full capacity
without overcharging. The value of this voltage will depend upon the type of battery or
charging stages selected (The type of battery and charging stages are selected with the
help of DIP Switches (7) - See Section 7 under "DIP Switch Setting" on page 21):
• 14.4V (SEC-1250UL) or 28.8V (SEC-2425UL) when Flooded / AGM
battery is selected
• 14V (SEC-1250UL) or 28V (SEC-2425UL) when Gel Cell battery is selected
• 13.5V (SEC-1250UL) or 27V (SEC-2425UL) when loaded battery is
selected (2 stage charging)
However, this constant voltage is not seen immediately because the charger enters cur-
rent limit as soon as it enters point (C2). As the charger voltage has been increased, the
battery will try to draw higher value of current which will be equal to the difference
between this higher voltage and the actual intrinsic voltage of the battery divided by
the internal resistance of the battery (.02 Ohm). The value of this current at the transi-
tion point (C2) will be higher than the current limit value forcing the charger to enter
current limit condition once again. As the charger is in current limit condition, it does
not regulate its output voltage. The voltage at the charger terminals is the actual inter-
nal battery voltage at that point (C1). Once again, the battery starts charging further at
the maximum rated constant current of 50A for SEC-1250UL / 25A for SEC-2425UL (C2 to
D2). The battery voltage also starts rising further (C1 to D1).
At point (D2), the charging current reduces to less than the current limit value of 50A
for SEC-1250UL / 25A for SEC-2425UL and the charger now exits current limited constant
current mode and enters constant voltage mode of 14V / 14.4V for SEC-1250UL and
28V / 28.8V for SEC-2440UL (point D1). (Please note that the voltage of 14V / 14.4V or
12 | SAMLEX AMERICA INC.
Principle of Operation
" PHASe)
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" Phase) At Point "C".
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