Samlex Europe SEC - 1215E Owner's Manual - Charging Stages
CHARGING STAGES
NOTE ! - 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 to1.1V. 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 0.8to1.1V higher than the
specified float voltage. Note that thes pecified float voltage is at a load of1A. Also, the voltage
on the terminals not connected to the load (forexample,whenone bank of battery is connected
to one positive terminal, the other 2 positive terminals will remain disconnected) will read
0.8to1.1Volt higher than the voltage of the loaded terminal.
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 page 7 ). The charging stages are
described below :
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-1215E/
SEC-2415E and 30A for SEC-1230E). 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 voltage. The constant current injected into the battery starts restoring
the battery capacity and it‘svoltage 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). 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.)
STAGE 2 -CONSTANT VOLTAGE BOOST OR ABSORPTION STAGE
As explained above, whenthebatteryvoltageapproaches the pointwhere 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). 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 current reduces below the preset threshold, the charger automatically
switches to the “Float or Maintenance Stage“.
STAGE 3 -CONSTANT VOLTAGE, FLOAT OR MAINTENANCE CHARGING STAGE
As explained above, as the charging current drops below the preset threshold ( 1.5 to 2 amps for
SEC-1215E / SEC-2415E and 2.5A to 3A for SEC-1230E ), it signals that the battery is 100%
charged. In this “Float or Maintenance Charging Stage“, the charger outputs a constant voltage
of 13.8V for 12V system and 27.6V for 24V system. This helps in maintaining 100% capacity of
the battery and also compensates for self discharge. The battery can remain connected in this
stage in definitely without the risk of overcharging or excessive loss of electrolyte.
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