Samlexpower SEC-1280UL Guide D'utilisation page 13

SECTION 4 |
4.3.1.3 Charging Characteristics during Bulk Stage
• Battery is charged at constant current equal to Bulk Stage Current rating of 80A
for SEC-1280UL and 40A for SEC-2440UL
• Battery voltage rises slowly and almost linearly till 13.5V for SEC-1280UL and till
27.0V for SEC-2440UL
• The entire charging current is used to convert (i) Lead Sulfate to Sponge Lead at
the Negative plates and (ii) Lead Sulfate to Lead Dioxide at the Positive plates
• There is minimal gassing and the charging efficiency is high - around 91%
• The restored capacity in this stage is inversely proportional to the Charging Rate
(due to Peukert's Effect). This means that as the charging rate is increased, the
capacity restored in this stage will also be reduced. This Bulk Stage will restore (i)
60% capacity at Charging Rate of C/5, (ii) 70%-75% capacity at Charging Rate of
C/10 and (iii) 85% to 90% capacity at Charging Rate of C/20
• Red LED marked "Bulk"/"I Phase" on the optional Remote Model 900-RC will be
lighted
4.3.2 Stage 2 - Absorption Stage
Refer to the Charging Curves at (i) Fig 4.1 for SEC-1280UL and (ii) Fig 4.2 for SEC-2440UL
4.3.2.1 General Information: The charger enters Absorption Stage at points "B1" (Voltage
Curve) and "B2" (Current Curve) after completion of Bulk Stage (Section 4.3.1). Absorption
Stage is carried out at constant voltage at 2 voltage levels - (i) Absorption Voltage Level 1
at 13.5V for SEC-1280UL or, 27.0V for SEC-2440UL and then, (ii) Absorption Voltage Level
2 at (i) 14.0/14.4 V for SEC-1280UL (selected through DIP Switches S1 and S2 - See Section
7.4 and Table 7.1) or, (ii) 28.0/28.8V for SEC-2440UL (selected through DIP Switches S1 and
S2 - See Section 7.4 and Table 7.2)
4.3.2.2 Absorption Stage Timer: When the charger enters Absorption Stage Level 1 (Sec-
tion 4.3.2.3.1), a 4 Hr / 8 Hr Absorption Stage Timer (Selected by DIP Switches "S3" and
"S4"- See Section 7.5, Table 7.3) is activated. When this Timer runs out, the charger will
transition from Absorption Stage to Float Stage (Section 4.3.3).
4.3.2.3.1 Absorption Stage Level 1: Charging is carried out at constant voltage of 13.5V
for SEC-1280UL or, 27.0V for SEC-2440UL (Section B1 to C1 of Voltage Curve in Figs 4.1
and 4.2). The intrinsic (internal) voltage of the battery rises further and its current starts
to taper down (Section B2 to C2 of Current Curve in Figs 4.1 and 4.2). The charging cur-
rent tapers down because the intrinsic (internal) battery voltage is rising and the differ-
ential voltage between 13.5/27.0V of the charger and the intrinsic (internal) voltage of
the battery is reducing, thereby, lesser current is driven into the battery. Tapering charge
at 13.5V / 27.0V is provided in this Absorption Stage Level 1 to reduce surface charge ef-
fect and to ensure that the charge slowly diffuses to the internal thickness of the plates
and prevents overcharging. When the charging current tapers down to 80% of the Bulk
Stage Current value of the charger (64A for SEC-1280UL or, 32A for SEC-2440UL) at point
Principles of Operation
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