Charging Stages & Protections - Samlexpower SEC-1215UL Owner's Manual

SECTION 4 |
4.1 CHARGING STAGES
i
INFO
a) VOLTAGE READINGS ON NO LOAD
The output has one common Negative terminal and three Positive terminals
for charging 3 banks of batteries. Each Positive terminal has an internal
isolating diode in series which has a forward voltage drop of 0.8 to 1.1 V. On
no load (that is when no battery or other DC load is connected to any of the 3
terminals) , the voltage reading will read 0.8 to 1.1 V higher than the specified
float voltage. Note that the specified float voltage is at a load of 1 A. Also,
the voltage on the terminals not connected to the load (for example, when
one bank of battery is connected to one Positive terminal, the other 2 Positive
terminals will remain disconnected) will read 0.8 to 1.1 Volt higher than the
voltage of the loaded terminal.
b) VOLTAGE SPECIFICATIONS
All rated voltages are specified at battery temperature of 80°F.
These chargers can be manually selected to operate in 3 stage or 2 stage modes (Please
see "Selecting the Type of Battery and Charging Stages" at Section 5.2.2). The charging
stages are described below:
4.1.1 Stage 1 - Constant Current or Bulk Charge Stage
When the battery is low, it will try to draw larger charging current. The charger senses
the current draw and limits this to the maximum permissible value (15A for SEC-1215UL /
SEC-2415UL and 30A for SEC-1230UL). Bulk charging takes place at this constant current.
In this condition of constant current, the voltage measured at the charger or battery
terminals will be the battery's own intrinsic voltage proportional to its state of charge.
The constant current injected into the battery starts restoring the battery capacity and it's
voltage starts rising. When this voltage approaches the threshold of battery "gassing",
termed "Boost or Absorption Voltage", the charger automatically switches over to Stage 2
- "Boost or Absorption Stage". The value of this voltage depends upon the type of battery
being charged (See DIP Switch Settings in Section 5, Tables 5.1 and 5.2). By this time,
approximately 80% of the battery capacity will normally have been restored (Note: The
percentage capacity restored till the point the battery reaches the Boost or Absorption
Voltage is inversely proportional to the value of the bulk charge current).
4.1.2 Stage 2 - Constant Voltage Boost or Absorption Stage
As explained at Section 4.1.1, when the battery voltage approaches the point where
battery "gassing" can begin, the charger automatically switches over to the "Boost or
Absorption Stage". The charger applies a constant voltage whose value depends upon
the type of battery selected (See DIP Switch Settings in Section 5, Table 5.1 and 5.2). This
controlled overcharge restores the balance 20% of the capacity in a minimum amount of
time. As the capacity is fully restored, the charging current starts reducing. When the cur-
rent reduces below the preset threshold (1.5 to 2A for SEC-1215UL / 2415UL and 2.5 to 3A
for SEC-1230UL), the charger automatically switches to the "Float or Maintenance Stage".
Charging States & Protections
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