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 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.
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
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). 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, 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 ). 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
charged. In this “Float or Maintenance Charging Stage”, the charger outputs a constant voltage of
13.5 V for 12 V system and 27 V for 24 V system. This helps in maintaining 100% capacity of the
battery and also compensates for self discharge. The battery can remain connected in this stage
indefinitely without the risk of overcharging or excessive loss of electrolyte.
Page 4
TROUBLESHOOTING
SYMPTOMS WHEN THE CHARGER IS POWERED AND CONNECTED TO
THE BATTERY
THE RED LED IS OFF
The DC side fuse may have blown due to wrong polarity of battery connection. Ensure positive of
the battery is connected to the positive of the charger and the negative of the battery is connected
to the negative of the charger. Check the fuses inside the charger and replace, if blown.
The battery may be shorted. In this condition, the unit is shut down by the short circuit protection
circuit. Remove the battery connection. If the red LED now comes on, the battery is shorted. If the
red LED still does not come on, check if there is AC power in the receptacle. If there is power,
check the AC side fuse inside the unit . If the fuse is not blown, call Technical Support.
THE RED LED IS ON BUT THE AMMETER SHOWS NO READING
The battery is fully charged . If the battery is not fully charged , the connection to the battery may
be loose or open. Check tightness and continuity of the battery connection.
THE BATTERY IS GETTING OVER CHARGED OR BOILS
The charger is also feeding other DC load(s) in parallel with the battery. The Dip Switch is not
selected for “Battery with Load”. Change Dip Switch setting to “ Battery under Load” ( see under
“Powering other DC loads” on page10.
SYMPTOMS WHEN THE CHARGER IS POWERED AND DIS-CONNECTED
FROM THE BATTERY
THE RED LED IS OFF
Check there is AC power in the receptacle. If there is power, check the AC side fuse inside the unit.
If the fuse is not blown, check the DC side fuse. If the DC side fuse is not blown, the output may
be shorted. In this condition, the charger is shut down by the short circuit protection circuit. Check
that the output terminals are not shorted. If the terminals are not shorted , call Technical Support.
AC SIDE FUSE BLOWS AS SOON AS POWER IS TURNED ON
Check that the AC input voltage is 120 VAC
If the AC input voltage is correct, the charger is defective. Call Technical Support
DC SIDE FUSE BLOWS AS SOON AS THE BATTERY IS CONNECTED
Wrong polarity of the battery connection. Ensure positive of the battery is connected to the
positive of the charger and the negative of the battery is connected to the negative of the charger.
Page 11
constant current, the voltage measured at the charger or battery terminals will be the battery’s own
draw and limits this to the maximum permissible value (15A for SEC-1215A / SEC-2415A and
voltage. The constant current injected into the battery starts restoring the battery capacity and it’s
30A for SEC-1230A). Bulk charging takes place at this constant current. In this condition of
SEC-1215A / SEC-2415A and 2.5 A to 3 A for SEC-1230A ), it signals that the battery is 100%
