SamplexPower SEC-1250UL Guide D'utilisation page 11

SECTION 4 |
NOTES FOR FIGS 4.1 & 4.2
Please note the following important information related to the Charging Curves
shown in Figs 4.1 and 4.2 above:
1. Terminal Voltage reading at charger Output Connectors on no load and on load:
(a) The Output Connectors of the charger consist of one common Negative Con-
nector (3, Fig 3) and two Red Positive Connectors (1, 2 in Fig 3) for charging
two banks of batteries. Each of the two Positive Connectors of the two banks
has Schottky Diodes in series for isolation. These isolating Schottky Diodes have
a current dependent forward voltage drop "Vf" ranging from 0.2 to 0.3V (at
0.1A) to 0.6V (at 50A). In addition, there will be additional forward drop "Vb"
across the bulk resistance of the Schottky Diodes and this drop will also increase
with increase in charging current. Please note that the forward voltage drops
"Vf" and "Vb" occur only when current flows through the Schottky Diode i.e.
when the charger is supplying current to the battery / load.
(b) The Float and Absorption voltages are tightly regulated before the isolating
Schottky Diodes. However, the voltages available at the terminals of the two
banks will vary with the value of the charging current because of the current
dependent forward voltage drop "Vf" and bulk resistance drop "Vb" of the
Schottky Diodes. The Float Voltage before the Schottky Diodes is, therefore,
set 0.2 to 0.3V higher to compensate for the forward drops during Float Stage
when the charging current would have dropped to less than 1A. Hence, the
output voltage at the Output Connectors of the two banks at no load (nothing
connected to the Connectors of the banks) will read 0.2 to 0.3V higher than the
Float Voltage of 13.5 / 27.0V because there is no forward voltage drop as there
is no current flow through the Schottky Diodes. The voltages are specified with
respect to charging / load current as follows:
Table 4.2 Terminal Voltages
Charging Stage
Absorption Stage - SEC-1250UL
Absorption Stage - SEC-2425UL
Float Stage - SEC-1250UL
Float Stage - SEC-2425UL
Open Circuit - SEC-1250UL
Open Circuit - SEC-2425UL
Bulk Stage - SEC-1250UL
Bulk Stage - SEC-2425UL
Principles of Operation
Output Voltage
13.5V
27.0V
14.4 / 14V for SEC-1250UL
28.8 / 28V for SEC-2425UL
13.5V
27.0V
13.7 to 13.8V
27.2 to 27.3V
(Internal voltage of charger)
(Internal voltage of charger)
Output Current
At 5A +/- 0.5A
At 3A +/- 0.5A
At 0.1A
At 0.1A
At 0A
At 0A
40 - 50A
20 - 25A
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