Samlexpower SEC-1245A Owner's Manual - page 11
BATTERY VOLTAGES – CHARGED AND DISCHARGED CONDITIONS
The cell voltage of a battery depends upon the temperature of the battery and has a
negative temperature coefficient – the voltage level increases at lower temperature and
decreases at higher temperature. The voltages are normally specified at 80º F (26.7º C)
On a 12 volt battery, the no load battery voltage is between 11.4 VDC (fully discharged)
and 12.9-13.0 VDC (fully charged). On a 24 volt battery, the no load battery voltage is
between 22.8 VDC (fully discharged) and 25.8 -26.0 VDC (fully charged).
CHARGING STAGES - I, Uo, U
The charger is preset to charge in 3 stages as described in the succeeding paragraphs. The
charger is called “IUoU Charger” based on the DIN designation of the charging stages – I
Phase, Uo Phase and U Phase. Please refer to the charging curve given at Figure 1 for
understanding the 3 charging stages
NOTE:
The charging voltages indicated below pertain to battery temperature of 80º F
Stage 1 - Constant Current, Bulk Charge Mode (I Phase):
When the charger is first
connected to a battery, the battery will start drawing current proportional to the dis-
charged condition of the battery. When the battery is deeply discharged, it will initially
try to draw a very large current. If this initial current draw is more than 45 A (SEC-
1245A) or more than 25A (SEC-2425A), the charger will enter Stage 1 – The Bulk
Charge Mode (I Phase). During this period, SEC-1245A will deliver a constant current I
= 45 A and SEC-2425A will deliver a constant current I = 25 A. The charger will be
operating under current limit condition and the voltage at the charging terminal will be
same as the actual voltage of the discharged battery. The voltage of the battery will
slowly start rising and when the battery voltage approaches voltage U = 13.8 V (SEC-
1245A) or voltage U = 27.6 V (SEC-2425A), the current drawn by the battery will
reduce below the current limit value of 45 A (SEC-1245A) and 25 A (SEC-2425A). The
charger will exit current limit condition and will now output constant voltage of U = 13.8
V (SEC-1245A) or constant voltage U = 27.6 V (SEC-2425A). The battery will continue
to charge at this constant voltage and its charging current draw will reduce further. When
the charging current drawn by the battery reduces below 80% of the charger capacity “I”
i.e. 36 A (for SEC-1245A) or 20 A (for SEC-2425A), the charger will automatically
switch over to Stage 2 – Constant Over-voltage, Timed Absorption / Boost Charge Stage
(Uo Phase).
During this Stage, following LED indications are provided:
•
Charging Indicator LED (4) on the front panel turns red
•
Red LED under “I Phase” is lighted on the Remote
Panel (15) ( Optional accessory)
Note:
When Mute Mode is selected (See under “Mute Mode / Reduction of Maximum
Charging Capacity”), the fan is disabled to cut out fan noise for a quiet operation. To
reduce heat dissipation during the Mute Mode, the maximum charging capacity (current
limit value) of the charger is reduced as follows:
•
Current limit of SEC-1245A is reduced to 16 – 18 A
instead of 45 A
•
Current limit of SEC-2425A is reduced to 8 A to 10 A
instead of 25 A
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