SamplexPower SEC-1245A User manual

Owner's
Manual
Please read this
manual before
operating your
power supply
Desktop Switching
Power Supplies
Model:
SEC-1245A
SEC-2425A

Importantsafetyprecautions................................................................2
Description..........................................................................................3
Features..............................................................................................3
Components and accessories..............................................................4
Specifyingleadacidbatteriesandchargers..........................................5
Chargingstages...................................................................................9
Cooling.............................................................................................12
Protections.......................................................................................13
Installation........................................................................................14
Preparingthechargerforoperation....................................................15
Remote Panel ..................................................................................19
Operation.........................................................................................20
Troubleshooting................................................................................23
Internal/externalfuseratings.............................................................25
Specifications....................................................................................26
Warrantyinformation.........................................................................27
CONTENTS
Page 1

IMPORTANT SAFETY PRECAUTIONS
Hazardous conditions may result if the charger is not installed or operated correctly.
Please read the following instructions to prevent personal injury or damage to the
charger.
BATTERYRELATED
•To reduce the risk of battery explosion, follow these instructions and those marked
on the battery.
•Never smoke or allow an open spark or flame in the vicinity of the battery or the
engine.
•Charge only LeadAcid type of batteries (Flooded / Absorbed Glass Mat (AGM)
/ Gel Cell). Do not charge other type of batteries like Nickel Cadmium (NiCad),
Nickel-Metal Hydride (Ni-MH), Dry-Cell etc. Other types of batteries might
burst causing personal injury.
•Never charge a frozen battery.
•Working in the vicinity of Lead Acid batteries is dangerous. Batteries generate
explosive gases during normal operation. Take necessary safety precautions when
installing the charger near a battery or in a battery compartment (Follow safety
instructions given by the battery manufacturer).
•Neverplace thecharger directlyabove orbelow thebattery beingcharged; gasesor
fluids from the battery will corrode and damage the charger. Locate the charger as
far away from the battery as DC cables permit. Do not install in the same com-
partment as batteries.
CHARGERRELATED
•Do not operate the charger in a closed-in area or restrict ventilation in any way.
Install in a well ventilated, cool, dry place.
•The charger must not be operated in a damp or wet environment. When mounting
in a boat, make sure it is not subjected to bilge water splash.
•Do not block the ventilation openings / openings for the cooling fan. There should
be at least 6 inches clearance all around the unit.
•Installation and wiring must comply with the local and the national electrical
codes. It is recommended that installation and wiring may be done by a certified
electrician.
•Wrong installation on a boat may lead to corrosion of the boat. It is recommended
that installation on the boat must be carried out by a boat electrician.
•Disconnect the AC input power to the charger before connecting / disconnecting
the batteries or other DC loads or when working on the charger.
•Disconnect the AC input power before changing the setting of the Dip Switches.
•The chassis of the charger is connected to the earth ground pin of the power cord
plug. Ensure that the earth ground pin of AC receptacle feeding the charger is
connected to earth ground.
•Do not use an adapter. If a grounding type of receptacle is not available, do not use
this charger until the proper outlet is installed by a qualified electrician.
•Do not operate the charger if the power cord is damaged.
Page 2

DESCRIPTION
SEC-1245A(for 12V batteries)and SEC-2425A (for 24 V batteries) are high current, 3 Stage
Chargersthatdeliver 45Aand 25Arespectively for almost 75% to 80% of the charging cycle
ensuring a very fast, safe and complete charging of lead acid batteries. The nomenclature “
I Uo U” is a DIN nomenclature and signifies the 3 charging stages – I for constant current
Bulk Charge Stage 1, Uo for constant over voltage Absorption / Boost Stage 2 and U for
constantvoltage Float / Maintenance Stage 3 ( under DIN specification, voltageis designated
“U” and current is designated “I”. The subscript “o” in “Uo” signifies over voltage).
FEATURES
Page 3
•Fully automatic – “Connect and Forget” operation.
•Suitable for flooded , AGM or Gel Cell type of lead acid batteries.
•State-of-the-art switched mode technology is used for high efficiency, lightweight
and quiet operation.
•User selectable 2 or 3-Stage automatic charging algorithm with timed Boost /
Absorption Stage and temperature compensation ensures rapid, safe and full
return of capacity.
•Ability to reduce maximum charging current to approximately 1/2 of the rated
capacity during “Half Power Mode”. This allows safe charging of lower capacity
batteries.
•Includes a Battery Temperature Sensor allowing temperature compensated charg-
ing, if required.
•2 banks of batteries can be charged simultaneously without the use of an external
battery isolator. The charging current will be shared between the two banks de-
pending upon the depth of discharge of the connected batteries.
•3 colour LED indicates charging status.
•Fan cooled - fan on/off based on output current.
•Protections against short circuit, over current, reverse battery connection and
over-temperature.
•Can be used as a power supply or as a DC UPS ( Uninterruptible Power Supply)
when used in conjunction with a battery.
•Optional Remote LED Panel with 10 Metres of wire for remote on / off control
and indication of charging status.

COMPONENTS AND ACCESSORIES
1. Output Connnector + Bank 1
2. Output Connector + Bank 2
3. Output Connector - Common
4. Charging Indicator LED
5. DIP Switches for mode selection
6. Jack for Remote Panel
7. Push Switch for Half Power Mode
8. LED for Half Power Mode indication
9. AC input Power On / Off Switch
10. AC fuse holder
11. Cooling fan
12. Jack for Temperature Sensor
13. AC power cord inlet
14*. Cable with plug
15*. Remote Panel
(*14 & 15 are optional accessories)
16. Temperature sensor element
17. Plug
47
53
11
12
10 13
14 15
16 17
Page 4
6812
9

SPECIFYING LEAD ACID BATTERIES AND CHARGERS
FLOODED/WETCELLANDSLA(SEALEDLEADACID)BATTERIES
There are two categories of lead acid batteries – Flooded/Wet Cell and Sealed Lead Acid
(SLA). A flooded/wet cell battery has a high tolerance to overcharging. However, it will
release hydrogen gas when charging that must be properly vented and the water level must
be checked frequently. SLAbatteries can either be Gel Cell orAGM (Absorbed Glass Mat).
Both the Gel Cell and AGM are maintenance free, have no liquid to spill and gassing is
minimal. The Gel Cell is the least affected by temperature extremes, storage at low state of
chargeandhas a low rate of self discharge.AnAGM battery will handle overchargingslightly
better than the Gel Cell.
Lead-acid batteries can be categorized by the type of application: Automotive service -
Starting/Lighting/Ignition (SLI, a.k.a. cranking) and Deep Cycle service.
SLIBATTERIES
Everybody is familiar with the SLI batteries that are used for automotive starting and
powering vehicular accessories. SLI batteries are designed to produce high power in short
bursts but must be constantly recharged (normally with an alternator while driving). Vehicle
starting typically discharges 1%-3% of a healthy SLI battery’s capacity.
The automotive SLI battery is not designed for repeated deep discharge where up to 80 % of
the battery capacity is discharged and then recharged. If an SLI battery is used for this type
of application, its useful service life will be drastically reduced.
DEEPCYCLEBATTERIES
Deep cycle batteries are designed with thick-plate electrodes to serve as primary power
sources, to have a constant discharge rate, to have the capability to be deeply discharged up
to 80 % capacity and to repeatedly accept recharging. They are marketed for use in recre-
ation vehicles (RV), boats and electric golf carts – so they may be referred to as RVbatteries,
marine batteries or golf cart batteries. There are two categories of deep cycle lead acid
batteries – wet and sealed.Awet cell battery has a high tolerance to overcharging. However,
it will release hydrogen gas when charging that must be properly vented and the water level
must be checked frequently. Sealed batteries can either be Gel Cell orAGM (Absorbed Glass
Mat). Both the Gel Cell andAGM are maintenance free, have no liquid to spill and gassing
is minimal. The Gel Cell is the least affected by temperature extremes, storage at low state of
chargeandhas a low rate of self discharge.AnAGM battery will handle overchargingslightly
better than the Gel Cell.
Page 5

REDUCTIONINUSABLE CAPACITYATHIGHERDISCHARGERATES
As stated above, the rated capacity of the battery inAH is generally applicable at a discharge
rate of 20 Hours. As the discharge rate is increased, the usable capacity reduces due to
“Peukert Effect”. This relationship is not linear but is more or less according to the table
below:
Table 1. Battery Capacity versus Rate of Discharge for a 20 Hr Discharge Rate
Hours of Discharge Usable Capacity
20 100%
10 87%
8 83%
6 75%
5 70%
3 60%
2 50%
1 40%
Using the above table will show that a 100AH capacity battery will deliver 100% (i.e. full
100AH) capacity if it is slowly discharged over 20 hours at the rate of 5Amperes. However,
if it is discharged at a rate of 50Amperes then theoretically, it should provide 100 AH ÷ 50
= 2 hours. However, the Table above shows that for 2 hours discharge rate, the capacity is
reduced to 50% i.e. 50AH. Therefore, at 50Ampere discharge rate the battery will actually
last for 50 AH÷50 Amperes = 1 Hour.
UNITSOFBATTERYCAPACITY
The battery capacity is the measure of the energy the battery can store and deliver to a load.
It is determined by how much current any given battery can deliver over a stipulated period
of time. The energy rating is expressed in Ampere Hours (AH). For example, as one of the
bench marks, the battery industry rates batteries at 20 hour rate i.e. how many Amperes of
current the battery can deliver for 20 hours at 80 º F till the voltage drops to 10.5 Volts for
12 V battery and 21 V for 24 V battery. For example, a 100 AH battery will deliver 5
Amperes for 20 hours. Other bench mark discharge rates are 8-hour rate for UPS batteries &
10-hour rate for telecom batteries. Battery capacity is also expressed as Reserve Capacity
(RC)in minutes. Reserve capacity is the time in minutes for which the battery can deliver 25
Amperes at 80 º F till the voltage drops to 10.5 Volts for 12 V battery and 21 V for 24 V
battery. Approximate relationship between the two units is as follows:
Capacity in AH = Reserve Capacity in RC minutes x 0.6
Page 6
BCI * Group Battery Voltage, V BatteryAH
27 / 31 12 105
4 D 12 160
8D 12 225
GC2** 6 220
* Battery Council International ** Golf Cart
TYPICALBATTERYSIZES
Below is a chart of some battery sizes applicable for powering inverters:

DEPTHOFDISCHARGEAND BATTERYLIFE
The more deeply a battery is discharged on each cycle, the shorter the battery life. Using
more batteries than the minimum required will result in longer life for the battery bank. A
typical cycle life chart is given at Table 2 below:
Table 2. – Typical Cycle Life Chart
Depth of Discharge Cycle Life Cycle Life Cycle Life
% of AH Capacity Group 27 / 31 Group 8D Group GC2
10 1000 1500 3800
50 320 480 1100
80 200 300 675
100 150 225 550
LOSSOFBATTERYCAPACITYATLOWTEMPERATURES
Batteries lose capacity at low temperatures. At 32 º F, a battery will deliver about 70 to 80
% of its rated capacity at 80 º F. If the air temperature near the battery bank is lower than 80
º F, additional batteries will be needed to provide the same usable capacity. For very cold
climates, an insulated / heated battery compartment is recommended.
SERIESANDPARALLELCONNECTION OFBATTERIESAND BATTERYBANKS
When two or more batteries are connected in series, their voltages add up but their AH
capacity remains the same. This series connection is also called a “string”. For example,
when two 12 V, 105AH batteries are connected in series, it becomes a 24 V, 105AH battery.
(Positive of the first battery is the positive terminal of the series connection. The negative of
the first battery is connected to the positive of the second battery. The negative of the
second battery is the negative of the series connection).
When two or more batteries or battery “strings” are connected in parallel, their voltages
remain the same but their capacities add up. For example, if two 12 V, 105AH batteries are
connected in parallel, their voltage remains 12 V but their capacity becomes 105 × 2 = 210
AH (Connect the positive terminal of the first battery to the positive terminal of the second
battery. These paralleled common positive terminals become the positive terminal of the
parallel combination. Connect the negative terminal of the first battery to the negative
terminal of the second battery. These paralleled common negative terminals become the
negative terminal of the parallel combination).
A “bank” of battery may be a single battery or a series / parallel combination of a group of
batteries that is used for a particular DC power system. Two or more independent DC
power systems may use two or more associated independent battery “banks”. For example,
in an RV, one “bank” of battery is used for the vehicle’s Starting , Lighting and Ignition
System. A second “bank” of Deep CycleAuxiliary Batteries is used for running other DC
loads like inverter, etc.
It is recommended that the depth of discharge should be limited to 50 %
Page 7

CHARGINGBATTERIES
The batteries can be charged by using good quality AC powered battery charger or from
alternative energy sources like solar panels, wind or hydro systems. Make sure an appropri-
ate battery charge controller is used. It is recommended that the batteries may not be charged
at current > C/5 (where C is the AH capacity of the battery at 20 hour discharge rate).
Also, for complete charging (return of 100 % capacity ), it is recommended that a 3 stage,
temperature compensated charger may be used (Constant current bulk charging followed by
constant voltage boost / absorption charging followed by constant voltage float charging).
Page 8

CHARGING STAGES
NOTE: Voltage reading on no load. The output terminals of the charger consist of one
commonwhite /black negative terminal(3) and two red positive terminals (1, 2) for charging
two banks of batteries. Each of the two positive terminals of the two banks has a Schottky
Diode in series for isolation. These isolating diodes have a current dependent forwardvoltage
drop ranging from 0.2 to 0.3 V(at 0.1 A) to 0.6 V(at 45 A). Please note that the forward
voltage drop occurs only when current flows through the diode.
The Float and Absorption voltages are tightly regulated before the isolating diodes. How-
ever, the voltages available at the terminals of the two banks will vary with the value of the
charging current because of the current dependent forward voltage drop across the isolating
diodes. The Float and Boost /Absorption voltages before the diodes are, therefore, set 0.2 to
0.3 V higher to compensate for the above forward drop during float condition when the
charging current would have dropped to less than 1 A. Hence, the output voltage at the
terminals of the two banks at no load (nothing connected to the terminals of the banks) will
read 0.2 to 0.3 V higher because there is no forward voltage drop as there is no current flow
through the diodes.
Please also note that the output voltage at the two banks may differ between 0.2 to 0.6 V
depending upon the different values of the charging current being delivered through each.
Page 9
Stage 1
I Phase
Stage 2
Uo Phase
Timed for 4 / 8
Hours Stage 3,
U Phase
Current, I
Voltage V
Time, Hours
Figure 1 Charging Curve
Curve for
Current I
Uo
U
80% of current
capacity of
charger
Curve for
Voltage U, Uo
10% of current
capacity of
charger

BATTERYVOLTAGES – CHARGEDAND DISCHARGEDCONDITIONS
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 discharged
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 45A(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” = 25A. 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 25A (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
drawwill reduce further.When the charging currentdrawn by the battery reduces below 80%
of the charger capacity “I” i.e. 36A(for SEC-1245A) or 20A(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 “Half Power Mode” is selected (See under “Half Power Mode / Reduction of
Maximum Charging Capacity”), the maximum charging capacity (current limit value) of the
charger is reduced as follows:
•Current limit of SEC-1245A is reduced to 22.5A +/- 1A instead of 45 A
•Current limit of SEC-2425A is reduced to 12.5A +/- 1A instead of 25 A
Page 10

Stage 2 - Constant Overcharge Voltage, Timed Absorption / Boost Charge Mode (Uo
Phase): When the charger enters Stage 2 from Stage 1, the battery is approximately 70% to
80% recharged. As soon as it enters this stage, a timer circuit is also initiated. The timer
circuit can be selected to operate for 4 or 8 hours with the help of DIP Switches (5) (See
under “Selecting time for Absorption / Boost Stage”). During this stage, the charger will
output a higher constant overcharge voltage whose value will depend upon the type of
battery or charging stages selected ( The type of battery and charging stages are selected with
the help of DIP Switches (5) – See under “Selecting The Type of Battery and Charging
Stages”):
•14.4 V (SEC-1245A) or 28.8 V (SEC-2425A) when Flooded / AGM battery is
selected
•14 V (SEC-1245A) or 28 V (SEC-2425A) when Gel Cell battery is selected
•13.5 V (SEC-1245A) or 27 V (SEC-2425A) when loaded battery is selected (2
stagecharging)
The battery will further absorb charge at this voltage and the charging current will further
reduce. When the charging current reduces to approximately 10% of the charger capacity “I”
(4.5A+/0 .5Afor SEC-1245Aand 3A+/- 0.5 Afor SEC-2425A), the charger automatically
changes over to “Stage 3 - Float / Maintenance Charge Mode (U Phase)”. However, if the
charging current does not reduce to the above threshold level (because of some defective /
shorted cells or due to an external load in a loaded battery), the charger will be forced to
change-over to “Stage 3 or Float / Maintenance Charge Mode (U Phase)” after elapse of 4 or
8 hours determined by the selected duration of the timer circuit. The battery will be charged
to approx. 95% of its capacity by the end of this stage. Ideally it would be at 100%, but there
are some practical limitations like temperature effect etc that usually prevent full recharge.
During this Stage, following LED indications are provided:
•Charging Indicator LED (4) on the front panel turns orange
•Yellow LED under “Uo Phase” is lighted on the Remote Panel (15) ( Optional
accessory)
NOTE: The threshold of current for change-over between the Absorbtion / Boost Charge
Mode (“Uo” Phase) & the Float / Maintenance Charge Mode (“U” Phase) are
different as follows: SEC-1245A SEC-2425A
• From “Uo” Phase to “U” Phase 4.5 A +/- 0.5 A 3 A+/- 0.5A
• From “U” Phase to “Uo” Phase 9 A +/- 1 A 7 A +/- 1A
Stage 3 – Constant Voltage, Float or Maintenance Charge Mode (U Phase): During
this mode, the charger outputs a constant voltage U = 13.5 V (SEC-1245A) or 27 V (SEC-
2425A). This helps in maintaining full capacity of the battery and also provides replacement
charge to overcome self discharge of the battery. The battery can remain connected in this
stage indefinitely without the risk of discharging.
During this Stage, following LED indications are provided:
•Charging Indicator LED (4) on the front panel turns green
•Green LED under “U Phase” is lighted on the Remote Panel (15) ( Optional
accessory)
Page 11

CAUTION!
3stage charging is recommended for charging stand-aloneunloaded batteries(there is no load
connected to the battery when it is being charged). If a load is also connected simultaneously,
a part of the charger’s output current will be diverted to this load. Thus, the charger may
remain locked in Stage 2 if the current drawn by the load is more than the preset value of
threshold current determining change over from Stage 2 to Stage 3 .This will lead to over-
charging and loss of electrolyte.
For charging a battery when a load is also connected simultaneously, Stage 2 voltage should
be same as Stage 3. Select “Loaded Battery” with the help of DIP Switches (5) – See under
“Selecting the Type of Battery and Charging Stages”.
COOLING
The charger is cooled by convection and in addition, has a fan (11) for forced air cooling. The
fan will automatically switch on when the charger enters the Boost / Absorption Stage 2
(ChargingIndicator LED (4) willbe Orange) orthe Bulk ChargingStage1 (Charging Indicator
LED (4) will be Red). The fan will automatically stop when the charger enters Float Stage 3
(Charging Indicator LED will be Green). Pleasenotethat the fan will be off in the Float Stage
3 (The Charging Indicator LED will be Green).
The operation of the fan is controlled by the current supplied by the charger as follows:
SEC-1245A SEC-2425A
Switches on when change over
from Float stage (“U” Phase)
to Boost stage (“Uo” Phase) 9 A +/- 1 A 7 A+/- 1A
Switches off when change over
from Boost stage (“Uo” Phase)
to Float stage (“U” Phase) 4.5 A +/- 0.5A 3 A +/- 0.5A
In case the fan fails or if the cooling is not adequate due to higher ambient temperature,
inadequateair circulationor blockageof airventilation openings,the thermalsensor forover-
temperature protection will shut down the output voltage of the charger. The Charging
Indication LED on the front panel will turn red ( On the Remote Panel, the red LED “I
Phase”will light, the green LED “Power” will, however, remain lighted). Thecharger willbe
latched in this shut down condition and will not reset automatically even after the unit has
cooled down. To reset, the AC input power on / off switch (9) at the back of the unit has to
be switched off and on again.
Page 12

PROTECTIONS
The charger has the following protections:
SHORT CIRCUIT SHUT DOWN
In case of a short circuit on the output side, the output of the charger will be shut down. The
Charging Indication LED (4) on the front panel will turn red (On the Remote Panel (15), the
red LED “I Phase” will light, the green LED “Power” will, however, remain lighted). The
charger will be latched in this shut down condition and will NOTrecover automatically even
after the short circuit condition is removed. To reset, theAC input power on / off switch (9)
at the back of the unit has to be switched off and on again.
OVERLOADCURRENTLIMITING
Thecurrent drawn by the load is automatically limited to a maximum of 45Afor SEC-1245A
(22.5 A +/- 1 A in “Half Power Mode”) and 25 A for SEC-2425A (12.5 A +/- 1 A when in
“Half Power Mode”). If the load tries to draw a higher current than these limits, the output
voltage of the unit will start to drop. The unit will automatically recover when the overload
condition is removed.
REVERSEBATTERYCONNECTIONCUTOFF
The output is internally fused on the DC side – 2 x 30Afuses for SEC-1245A and 2 X 20A
fuses for SEC-2425A. In case, the polarity of the battery connection is reversed, the fuse(s)
will blow. The Charging Indication LED (4) on the front panel will turn red (On the Remote
Panel (15), the red LED “I Phase” will light, the green LED “Power” will, however, remain
lighted). The fuse(s) will be required to be replaced for the unit to function again.
THERMALOVERLOADSHUTDOWN
CAUTION!Keep the charger in a well ventilated, cool and open area. Do not block the vent
holes on the sides or the discharge openings of the cooling fan.
In case the fan fails or if the cooling is not adequate due to higher ambient temperature,
inadequateair circulationor blockageof airventilation openings,the thermalsensor forover-
temperature protection will shut down the output voltage of the charger. The Charging
Indication LED (4) on the front panel will turn red (On the Remote Panel (15), the red LED
“I Phase” will light, the green LED “Power” will, however, remain lighted). The charger will
be latched in this shut down condition and will NOT reset automatically even after the unit
has cooled down. To reset, theAC input power on / off (9) switch at the back of the unit has
to be switched off and on again.
PROTECTIONAGAINST TRANSIENTS / SURGES INTHEAC INPUT
In a number of locations, the AC line input is not clean and may contain high voltage
transients / surges. To prevent damage to the internal components against these unwanted
high voltages, the charger uses a MOV (Metal Oxide Varistor) for protection. If surge /
transient voltage higher than approximately 170 VAC appear in the AC input, the MOVwill
conduct and will blow the AC side fuse.
Page 13

INSTALLATION
LOCATION, MOUNTINGANDSAFETY
The charger is required to be installed in a safe, well ventilated and dry location. Please see
the details given under “Important Safety Precautions”.
The charger can be mounted horizontally or vertically. When mounting vertically, please
ensure that the axis of the fan rotor is horizontal (to reduce stress on the bearing).
OUTPUT CONNECTORS
Connectors with tubular, screw down type of terminals are used for output connection. The
diameter of the tubular hole of the connector is 8 mm (0.31 inches).
Two positive output connectors (1, 2) are provided for connecting to the positive terminals
of the 2 banks of batteries. One common connector (3) is provided for the negative connec-
tion.
TERMINALLUGS FORCONNECTION TOTHECHARGER
For firm connection when using stranded cable, crimp / solder “pin” style terminal lugs on
the charger end of the DC cables used for connecting to the battery / other DC loads.
3 pieces of “pin” style terminal lugs have been provided as follows:
• For SEC-1245A Will accomodate up toAWG # 4 cable
• For SEC-2425A Will accomodate up toAWG # 8 cable
CABLES
To avoid polarity errors and possible damage, never use cables of only one color. Use red
insulated cable(s) for positive connection(s) and black for negative connection(s).
Recommended DC cable sizes are given below (Based on a voltage drop of 2%). The length
in feet is the length of the pair of the positive and negative DC cables from the charger to the
battery / other DC loads.
Distance from battery SEC-1245A SEC-2425A
Up to 6 ft. AWG # 6 AWG # 10
6 to 10 ft AWG # 4 AWG # 8
10 to 20 ft. AWG # 1/0 AWG # 6
Page 14

PREPARING THE CHARGER FOR OPERATION
SELECTINGACINPUTVOLTAGE
The charger is pre-set to operate from AC input voltage of 120 VAC, 50 / 60 Hz.
To operate the charger from AC input voltage of 230 VAC, 50 / 60 Hz, change the internal
setting as follows:
1. Remove the bottom cover plate by removing the 4 screws. Please note that the bottom
cover plate has 4 rows of ventilation slots towards one end of the plate and this end with the
slots is placed towards the end of the housing with the output terminals.
WHEN THE BOTTOM COVER PLATE IS FITTED BACK, ENSURE THAT THIS END OFTHE PLATE THAT HASTHE
SLOTS IS TOWARDS THE TERMINAL SIDE OF THE HOUSING AND NOT TOWARDS THE OTHER SIDE OF THE
HOUSING THAT HAS THE FAN (THIS IS NECESSARY TO CREATE PROPER AIRFLOW PATH BYTHE SUCTION
CREATED BY THE FAN) .
2. Locate the yellow colored loop of wire with black colored, female quick disconnect terminal
lugs (here-in after called the “Shorting Link”). This is located towards the fan side and near
the two input filter capacitors and the bridge rectifier with the heat sink. In the pre-set
condition for 120 VAC operation, this Shorting Link shorts the two vertical pins located at
points marked “C” and “D” on the circuit board. For 230 VAC operation, remove the Shorting
Link by pulling the black quick disconnect lugs upward. Store this Shorting Link for conversion
back to 120 VAC operation, when required. Alternatively, disconnect any one end of the
Shorting Link by pulling the black terminal lug upwards. Tape the disconnected end with
insulation tape.
3. Replace the AC plug of the power cord with a suitable 3 pin grounded plug to
mate with the 230 VAC outlet.
CAUTION! The new plug should have 3 poles i.e. Line ( L ) , Neutral ( N ) and Earth ground.
Color code for the power cord conductors is : Line ( L ) - Black , Neutral ( N ) - White and
Earth Ground - Green).
CONNECTINGTHE BATTERIES OR OTHER DC LOADS
The output of the charger has a common Negative (-) connector (3) and 2 Positive connectors
(1, 2) for connection of 2 banks of batteries. Each Positive connector has its own internal
isolating diode which works as a battery isolator. If more than one bank of batteries is connected,
these will be charged at the same time as long as the AC power is available to the charger (the
maximum charging current of 45 A of SEC-1245A and 25 A of SEC-2425A will be shared among
the connected banks of the batteries depending upon their discharged states). In case the AC
power fails or if there is no output from the charger, the isolating diodes will prevent charging
/ discharging among the batteries connected to the banks.
CAUTION! When a single bank consisting of more than one battery in parallel is to be charged,
make sure that their negatives are connected to the common negative connector (3) of the
charger and their positives are connected to the same positive connector ( either 1 or 2) of the
charger. For example, when charging a bank consisting of 3 batteries connected in parallel, their
3 negative terminals should be connected to the common negative terminal (3) of the charger
and all their 3 positive terminals should be connected to the same positive terminal of the
charger ( either 1 or 2). Alternatively, the negative terminals of the 3 batteries should first be
shorted and then connected to the common negative terminal (3) of the charger and similarly,
the 3 positive terminals of the battery should first be shorted and then connected to one of the
2 positive terminals of the charger (either 1 or 2).
When connecting a single battery or other DC load, it can be connected to the common negative
(3) and any one of the 2 positive terminals (either 1 or 2)
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CHARGINGMORETHAN ONE BANKOFBATTERIES
CAUTION! When charging more than one bank of batteries at the same time using 3 Stage
Charging, ensure that the batteries in the banks are in a similar discharged condition. If one
bank is completely discharged and another is almost fully charged, the bank that is fully
charged will be subjected to over charge condition during the time when the charger remains
in Stage 2 (“Uo” Phase) for charging the completely discharged bank.
If 2 banks of batteries are required to be charged and they are at different discharged condi-
tions, select “Loaded Battery” (2 Stage Charging) with the help of switches S1 and S2 of the
set of 4 DIP Switches (5) (both S1 & S2 in off condition) – See under “Selecting the Type
of Battery and Charging Stages”.
SELECTINGTHE TYPEOFBATTERYANDCHARGINGSTAGES
The Float or Maintenance Charge Mode (“U” Phase) voltage andAbsorption / Boost Charge
Mode (“Uo” Phase) voltage of different types of Lead Acid Batteries are different.
3 Stage charging (Stages 1, 2 and 3) is recommended when charging stand alone, unloaded
battery (The battery has no load connected to it when it is being charged).
When the charger is used to charge a battery and simultaneously supply an external load, the
voltage level of Stage 2 is required to be set to the same level as the voltage of Stage 3 to
prevent over-charging. Effectively, the battery will be charged in 2 stages only – Stage 1 and
Stage 3. This also applies when two banks of batteries are being charged simultaneously and
the batteries in the two banks are in a dissimilar state of discharge.
A pair of switches S1 & S2 out of a set of 4 DIP Switches (5) has been provided for selecting
the battery type and for modifying the Boost Stage when charging loaded batteries / two
banks of batteries with different discharged states. The following selections can be made
with the help of the DIP Switches S1 and S2:
CAUTION! Do not change the DIP Switch setting when the charger is operating. Always
change the DIP Switch setting when the charger is off, i.e. after disconnecting the charger
from the AC input power).
NOTE: The voltages are for battery temperature of 80º F.
DIP Switch Setting for SEC-1245A
S1 S2 Float Boost Battery Type Charging Stages
/ Application
Stand-alonecharging
OFF * ON * 13.5 V * 14.4 V * Flooded / AGM * 3 Stages (Stages 1, 2, 3)
ON OFF 13.5 V 14.0 V Gel Cell 3 Stages (Stages 1, 2, 3)
Charging loaded battery
or
Charging two banks and the batteries in the two banks are in dissimilar discharged condition
OFF OFF 13.5 V 13.5V Loaded Battery 2 Stages (Stages 1, 3)
(can be Flooded
/ AGM / Gel Cell)
*Factory preset in this position
Page 16

DIP Switch Setting for SEC-2425A
S1 S2 Float Boost Battery Type Charging Stages
/ Application
Stand-alonecharging
OFF * ON * 27 V * 28.8 V * Flooded / AGM * 3 Stages (Stages 1, 2, 3)
ON OFF 27 V 28.0 V GelCell 3 Stages (Stages 1, 2, 3)
Charging loaded battery
or
Charging two banks and the batteries in the two banks are in dissimilar discharged
condition
OFF OFF 27 V 27.0 V Loaded Battery 2 Stages (Stages 1, 3)
(can be Flooded
/ AGM / Gel Cell)
*Factory preset in this position
CAUTION!
Please ensure that position S1- ON and
S2 – ON is never selected
SELECTINGTHETIMEFOR STAGE2 - CONSTANTOVERCHARGEVOLTAGE,
TIMEDABSORPTION / BOOST CHARGE MODE (“Uo” PHASE)
Stage 2 - Constant Overcharge Voltage, Timed Absorption / Boost Charge Mode (“Uo”
Phase) is controlled by an internal timer circuit. Time of 4 hours or 8 hours can be selected
with the help of a pair of switches S3 & S4 of the set of 4 DIP Switches (5). Select the times
as follows:
Time DIP Switch S3 DIP Switch S4 Type of Battery
4 hours* Off* On* Flooded / wet cell
8 hours On Off Gel Cell & AGM
Disable Off Off -
*Factory preset in this position
CAUTION!
Please ensure that position S3- ON and
S4 – ON is never selected
Page 17

REDUCTION OF MAXIMUM CHARGING CAPACITY TO HALF TO CHARGE
LOWERCAPACITYBATTERIES
Batteries should not be charged at very high currents to ensure long life. Normally, the
maximum charging current should be limited to approximately C/5 (where C is the AH
capacity of the battery at 20 hour rate). Thus, at the rated current capacities (45 A for SEC-
1245A and 25 A for SEC-2425A), the minimum AH capacity of the battery that should be
charged with the charger will be:
•45A x 5 = 225AH for SEC-1245A
•25Ax 5 = 125 AH for SEC-2425A
Thus, SEC-1245A should be used to charge battery with AH capacity > 225 AH and SEC-
2425A should be used to charge battery with AH capacity > 125 AH.
A provision has been made to reduce the maximum charging current to approximately half:
22.5A+/- 1Afor SEC-1245A& 12.5A+/- 1Afor SEC-2425A. This mode is termed as “Half
Power Mode”. This mode can be selected by pressing push switch (7) marked “Half Power
Mode”. When selected, a Green LED (8) marked “Half Power” will be lighted. When “Half
Power Mode” is selected, batteries with the following minimum capacities can be charged:
•SEC-1245A - 100 AH and above
•SEC-2425A - 55AH and above
TEMPERATURECOMPENSATION
The cell voltages of a battery depend upon the temperature of the cells inside the battery. The
cells have a negative temperature coefficient – their voltage levels increase at lower tempera-
ture and decrease at higher temperature. The negative temperature coefficient is – 2.8 mV / º
F / cell or - 16.8 mV / º F/ 6 cells for a 12 V battery or - 33.6 mV / º F / 12 cells for a 24 V
battery.
The battery and battery charger voltages are normally specified at a temperature of 80 º F
(26.7 º C). Thus, if the battery temperature is considerably lower than or higher than 80 º F,
it will be under-charged or over-charged unless the battery charger has temperature compen-
sation.
TEMPERATURESENSOR PROBETF-500
This charger has a provision for temperature compensation.A temperature sensor unit -
Model No. TF-500 (16, 17) is provided for this purpose.
CAUTION! This temperature sensor is matched and calibrated for each battery charger
and should not be interchanged with the sensor from another battery charger.
The temperature sensor comes with 5 Metre cable. It has a plug (17) on one end. Connect
this plug into the jack marked TS (12) on the rear panel of the charger. The other end has
the temperature sensor element (16). Mount this temperature sensor element flush with
the top surface of the battery for proper heat transfer.
When the temperature sensor is connected, the voltages during Stage 2 and Stage 3 are
automatically adjusted as per the temperature of the battery and the above temperature
coefficient.
Page 18

REMOTE PANEL - MODEL NO. 900-RC
An optional wired Remote Panel Model No. 900-RC (15) can be ordered. It comes with 10
metres of flat ribbon cable (14) that has 8 position modular male connector on either end.
The Remote Panel (15) can be used to switch on / switch off the charger and also monitor the
charging status of the charger from a remote location.
CONTROLS AND INDICATIONS
The Remote Panel has the following controls / indications:
•Keypad switch for switching on and switching off
•Red LED under “I Phase”
•Yellow LED under “Uo Phase” *
•Green LED under “U Phase”
•Green LED under “Power”
* Note: When “ Loaded Battery” application is selected (see pages 16 & 17), this will
indicate the Float stage (“U” Phase) as in this application, the Boost stage
voltage (“Uo” Phase) is the same as the Float stage voltage (“U” Phase).
CONNECTION
To connect the Remote Panel to the charger, insert one connector of the flat ribbon cable (14)
into the modular jack on the Remote Panel (15) and the other connector to the modular jack
(6) on the charger.
OPERATION
The charger should be first switched on with the help of theAC input power on / off switch
(9) located on rear panel of the charger.
The charger can now be switched on and off with the help of the keypad switch on the
Remote Panel (15).
INDICATIONS
Whenever the charger is switched on, the Green LED “Power” will be lighted. The other
LEDs indicate the charging status as follows:
•Red LED “I Phase” is lighted – Indicates that charger is in Stage 1 - Constant
Current, Bulk Charge Mode (“I” Phase) and is delivering 45 A to 36 A (SEC-
1245A) or 25 A to 20 A (SEC-2425A)
•Yellow LED “Uo Phase” is lighted – Indicates that the charger is in Stage 2 –
Constant Overcharge Voltage, Timed Absorption / Boost Charge Stage (“Uo”
Phase) and is delivering between 36A to 4.5 A (SEC-1245A) or between 20 Ato
2.5A(SEC-2425A)
•Green LED “U Phase” is lighted – Indicates that the charger is in Stage 3 -
Constant Voltage, Float or Maintenance Charge Mode (“U” Phase). The charger is
delivering < 4.5 A (SEC-1245A) or < 2.5 A (SEC-2425A). The battery is fully
charged.
Page 19