8 | SAMLEX AMERICA INC.
SECTION 4 |
Principles of Operation
i
INFO
For complete understanding of working of battery chargers, understanding of
operation of Lead Acid batteries is desirable.
For detailed information on construction, working and application of batteries,
please refer to White Paper titled "Batteries, Chargers and Alternators" at the
following link to Samlex America, Inc. website:
www.samlexamerica.com/support/whitepapers.aspx
4.1 SWITCH MODE POWER SUPPLY (
SMPS
) CHARGER
This unit is a Switched Mode Power Supply (
SMPS
) and charger that converts 120 / 230
VAC, 50 / 60 Hz to regulated DC voltages and limits the maximum output current equal
to the rated Bulk Stage Current (
Current Limit Value
) as shown in Table 4.1.
TABLE 4.1 CHARGING STAGE VOLTAGES AND CURRENTS
Model No.
Bulk Stage
Current
(
Current
Limit Value
)
Constant
Voltage in
Bulk Stage
Constant
Voltage in
Absorption
Stage
Constant
Voltage
in Float
Stage
Terminal
Voltage at
No Load
(
See Table 4.2
)
SEC-1250UL
50A
13.5 VDC
14.0 VDC or
14.4 VDC
13.5 VDC
13.7V to
13.8V
SEC-2425UL
25A
27 VDC
28 .0 VDC
or 28.8 VDC
27 VDC
27.2V to
27.3V
The specified output voltage of the charger during particular charging stage is held
constant till the Bulk Stage Current value is reached. When the battery or DC load tries
to draw current > the Bulk Stage Current value (
50A for SEC-1250UL & 25A for SEC-
2425UL
), the charger limits the current to the Bulk Stage Current value and the output
voltage of the charger drops and is no longer constant. When the charger is charging a
battery at current = the Bulk Stage Current, it will be in current limit condition and the
terminal voltage of the charger will drop but will be clamped to the actual lower intrin-
sic terminal voltage of the battery relative to its Stage of Charge at that time.