SamplexPower MSK-20A User manual

Solar
Charge
Controller
MSK-20A
Please read this
manual BEFORE
using your
Charge
Controller
Owner's
Manual

2 | SAMLEX AMERICA INC.
OWNER'S MANUAL | Index
SECTION 1
Safety Instructions................................................................. 3
SECTION 2
General Information, Features & Layout ............................... 5
SECTION 3
Installation ........................................................................... 7
SECTION 4
Operation ........................................................................ 13
SECTION 5
Protections & Troubleshooting ........................................... 18
SECTION 6
Specications ...................................................................... 23
SECTION 7
Warranty ........................................................................ 25
Disclaimer of Liability
UNLESS SPECIFICALLY AGREED TO IN WRITING, SAMLEX AMERICA INC.:
1. MAKES NO WARRANTY AS TO THE ACCURACY, SUFFICIENCY OR SUITABILITY OF ANY TECHNICAL OR OTHER INFORMATION
PROVIDED IN ITS MANUALS OR OTHER DOCUMENTATION.
2. ASSUMES NO RESPONSIBILITY OR LIABILITY FOR LOSSES, DAMAGES, COSTS OR EXPENSES, WHETHER SPECIAL, DIRECT, INDI-
RECT, CONSEQUENTIAL OR INCIDENTAL, WHICH MIGHT ARISE OUT OF THE USE OF SUCH INFORMATION. THE USE OF ANY
SUCH INFORMATION WILL BE ENTIRELY AT THE USERS RISK.
Samlex America reserves the right to revise this document and to periodically make changes to the content
hereof without obligation or organization of such revisions or changes.
Copyright Notice/Notice of Copyright
Copyright © 2021 by Samlex America Inc. All rights reserved. Permission to copy, distribute and /or modify this
document is prohibited without express written permission by Samlex America Inc.

2 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 3
SECTION 1 | Safety Instructions
IMPORTANT SAFETY INSTRUCTIONS
PLEASE READ THE FOLLOWING SAFETY INSTRUCTIONS BEFORE USING THE CHARGE CONTROLLER.
FAILURE TO ABIDE BY THE RECOMMENDATIONS MAY CAUSE PERSONAL INJURY / DAMAGE TO THE
CONTROLLER.
The following safety symbols will be used in this manual to highlight safety and information:
WARNING!
Indicates possibility of physical harm to the user in case of non-compliance.
!CAUTION!
Indicates possibility of damage to the equipment in case of non-compliance.
i
INFO
Indicates useful supplemental information.
WARNINGS !CAUTIONS!
1. This Charge Controller is not waterproof (Ingress Protection Rating is IP-30). PLEASE EN-
SURE THAT THE UNIT IS INSTALLED IN DRY, COOL AND WELL VENTILATED ENVIRONMENT.
2. Ground the Negative of the battery as follows:
• to Earth Ground in shore installations
• to Chassis Ground in Negative grounded mobile installations
3. There are no user serviceable parts inside the controller. Do not disassemble or
attempt to repair it.
4. Install external fuses / breakers as required.
5. Disconnect the Solar Panel(s) and fuse / breakers near to battery before installing or adjust-
ing the controller.
6. Conrm that power connections are tightened to avoid excessive heating from loose con-
nection.
7. The charge controller has been factory preset to optimally charge 12V / 24V Sealed Lead
Acid Batteries (AGM - Absorbed Glass Mat)
8. Comply with battery manufacturer’s recommendations.
9. Avoid charging damaged, defective or old battery.
10. Ensure correct polarity is maintained when connecting the Charge Controller to the battery
- Connect the Positive output terminal to the Positive Battery Post and the Negative output
terminal to the Negative Battery Post.
11. When charging, removal of the battery from the vehicle is not necessary provided the bat-
tery is being charged in a well-ventilated area.
12. Batteries contain very corrosive diluted Sulphuric Acid as electrolyte. Precautions should be
taken to prevent contact with skin, eyes or clothing. If battery electrolyte makes contact
with skin or clothing, ush immediately with water. See a doctor immediately.

4 | SAMLEX AMERICA INC.
SECTION 1 | Safety Instructions
13. Batteries generate Hydrogen and Oxygen during charging resulting in evolution of explosive
gas mixture in non-sealed batteries. Care should be taken to ventilate the battery area
when non-sealed batteries are used and follow battery manufacturer’s recommendations.
14. Ensure there are no ammable substances, explosive gases, ames, smoke or spark near
the battery or the Solar Panel(s).
15. Use caution to reduce the risk of dropping a metal tool on the battery. It could spark or
short circuit the battery or other electrical parts and could cause an
explosion.
16. Remove metal items like rings, bracelets and watches when working with batteries. Batter-
ies can produce a short circuit current high enough to weld a ring or the like to metal and
thus, cause a severe burn.
17. If you need to remove a battery, always remove the Negative (Ground) connection from the
battery rst. Make sure that all the accessories are off so that you do not cause a spark.
18. Solar Panel(s) generate electrical power when exposed to sunlight. Place a dark cover over
the panels when handling panels that have bare, un-insulated output wires. Accidental
shorting of panel terminals or wiring connected to the panels can result in spark causing
personal injury or a re hazard.
19. It is important that the battery gets fully charged frequently (at least once per week).
Otherwise, the battery can become permanently damaged due to under charging. Partially
charged batteries can quickly sulfate internally which is an irreversible condition. It is good
practice to prevent a battery from being discharged below 50%. Deeper discharging
severely shortens battery life.
20. Keep the surface of Solar Panel(s) clean from dust / dirt / leaves / other debris. Clean with a
soft wet cloth (to prevent scratching). Do not walk on the panels.
21. Installation and wiring must comply with the local and National Electrical Codes and must
be done by a certied electrician.

4 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 5
SECTION 2 | General Information, Features
& Layout
2.1 GENERAL INFORMATION
MSK-20A is a 20A rated, Series Type of PWM (Pulse Width Modulation) Charge Controller. It is
based on an advanced design using a microcontroller for digital accuracy and fully automatic
operation. It is designed to charge 12V / 24V Lead Acid Batteries..
2.2 FEATURES
- Advanced microcontroller based, high performance design for digital accuracy and fully
automatic and intelligent operation
- Series Type PWM (Pulse Width Modulation) charging for low loss, higher efciency
charging and longer battery life
- Up to 50V Open Circuit Voltage (Voc) and up to 20A Short Circuit Current (Isc) of PV Panel(s)
- Dual voltage capability – can be used with 12V / 24V batteries. 12V / 24V Nominal Battery
System is detected automatically: Battery voltage < 18V is detected as 12V battery and >18V
is detected as 24V battery
- 3 stages of charging for 100% return of capacity and for longer battery life
•Normal: Bulk Stage gAbsorption Stage gFloat Stage
- Factory preset for charging Sealed Lead Acid Batteries (AGM - Absorbed Glass Mat)
- User friendly LED display for monitoring of operation and self diagnostics for
troubleshooting
- Built-in or optional Remote Battery Temperature Sensor (Model MSK-TS) for battery
temperature compensation to ensure improved charging of batteries that experience wider
temperature variations during the year
- MOSFET based reverse current blocking for night-time battery discharge prevention. This
allows much lower losses as compared to Diode based blocking
- Protections: (i) Solar Panel over current (ii) Solar Panel short circuit (iii) Solar Panel
reverse polarity (iv) Battery reverse polarity (v) Battery over voltage (vi) Controller / battery
overtemperature (vii) Overload and short circuit protections on Load Terminals
2.3 APPLICATIONS
- Recreational / Service Vehicles
- Off grid
- Portable Charging Kits
- Boats and marine crafts
- Field work / mobile ofces
- Telecommunications

6 | SAMLEX AMERICA INC.
2.4 LAYOUT 1 2 3
4
5A 5B 6A 6B 7A 7B
5A 5B 6A 6B 7A 7B 98
LEGEND FOR FIG 2.1
Item No. Description Item No. Description
1 Solar Panel Status LED 6A Battery Terminal (+)
2 Battery Status LED 6B Battery Terminal (–)
3 Load Status LED 7A Load Terminal (+)
4
Load On/Off Button
Also used for clearing load size
overload and short circuit faults.
7B Load Terminal (–)
5A Solar Panel Input Terminal (+) 8
(See NOTE 1)
Connector for optional Remote Battery
Temperature Sensor Model "MSK-TS"
5B Solar Panel Input Terminal (–) 9 RS-485 Communication Port
(NOT USED)
NOTES: 1. If the Remote Battery Temperature Sensor is short-circuited or damaged, the control-
ler will charge or discharge at the default temperature setting of 25°C.
2. All terminal can accept conductor size up to AWG#8 / 10mm2
SECTION 2 | General Information, Features
& Layout
Fig 2.1: Layout of Charge Controller MSK-20A

6 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 7
SECTION 3 | Installation
3.1 SAFETY
WARNING! !CAUTION!
PLEASE READ ALL THE SAFETY INSTRUCTIONS GIVEN IN SECTION 1 BEFORE
INSTALLING AND OPERATING THE CONTROLLER. FAILURE TO ABIDE BY THE
RECOMMENDATIONS MAY CAUSE PERSONAL INJURY / DAMAGE TO THE KIT.
DO NOT USE THE UNIT IN WET ENVIRONMENT
• Please note that this unit is not waterproof (its Ingress Protection Rating is
IP-30). Ensure that the unit is installed in dry environment.
GROUNDING
• Ground the Negative terminal of the BATTERY (6B in Fig 2.1) to Earth Ground
in shore installation and to the Chassis Ground in mobile installations.
• DO NOT GROUND THE SOLAR ARRAY Negative when battery negative is
grounded.
BATTERY TYPES
• The unit has been factory preset to optimally charge 12/24V, Sealed (AGM)
Lead Acid Batteries.
MISE EN GARDE! !ATTENTION!
VEUILLEZ LIRE TOUTES LES INSTRUCTIONS DE SÉCURITÉ DONNÉES DANS
LA SECTION 1 AVANT D'INSTALLER ET D'UTILISER LE CONTRÔLEUR. NON-
RESPECT DE LA LES RECOMMANDATIONS PEUVENT PROVOQUER DES
BLESSURES OU ENDOMMAGER LE KIT.
N'UTILISEZ PAS L'APPAREIL DANS UN ENVIRONNEMENT HUMIDE
• Veuillez noter que cet appareil n'est pas étanche (son indice de protection
d'entrée est IP-30). Par conséquent, veuillez vous assurer que l'unité est
installée dans un environnement sec.
MISE À LA TERRE
• Mettez à la terre la borne négative de la batterie (6B, Fig 2.1) à la terre à la
terre dans l'installation à terre et à la masse du châssis dans les installations
mobiles à la terre négative.
TYPES DE BATTERIE
• L'unité a été préréglée en usine pour charger de manière optimale les
batteries au plomb-acide scellées (AGM) 12 / 24V.

8 | SAMLEX AMERICA INC.
SECTION 3 | Installation
3.2 DIMENSIONAL DRAWING
Dimensional drawing is given at Fig 3.1 below:
50
Solar Charge Controller
MSK-20A | 20 AMPS
Height: 47.8 mm
81.4
Mounting Hole: 4.3 mm Terminals: AWG#8 / 10 mm2
159.6
147
4.3
Fig 3.1: Dimensional Drawing of Charge Controller MSK-20A
3.3 MOUNTING
Refer to Fig 3.1
When mounting the controller, ensure free air through the ventilation slots at the bottom of the
unit. There should be at least 6 inches (150 mm) of clearance above and below the controller to
allow for cooling. If mounted in an enclosure, forced air ventilation is highly recommended.
WARNING!
RISK OF EXPLOSION! NEVER INSTALL THE CONTROLLER IN A SEALED ENCLO-
SURE WITH FLOODED BATTERIES! DO NOT INSTALL IN A CONFINED AREA
WHERE BATTERY GASSES CAN ACCUMULATE.
MISE EN GARDE!
RISQUE D'EXPLOSION! N'INSTALLEZ JAMAIS LE CONTRÔLEUR DANS UN
BOÎTIER SCELLÉ AVEC DES BATTERIES INONDÉES! NE PAS INSTALLER DANS
UNE ZONE CONFINÉE OÙ DES GAZ DE BATTERIE PEUVENT S'ACCUMULER.

8 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 9
3.3.1 Step 1: Choose Mounting Location
Locate the controller in area protected from direct sun, high temperature, and water. Make sure
there is good ventilation.
3.3.2 Step 2: Check For Clearance
Place the controller in the location where it will be mounted. Verify that there is sufcient room
to run wires and that there is sufcient room above and below the controller for airow. Ensure
cool air can move freely through the heat sink ns at the bottom of the unit.
3.3.3 Step 3: Mark Holes
Use a pencil or pen to mark the 4 mounting hole locations on the mounting surface, (Refer to
the dimensional drawing in Fig 3.1).
3.3.4 Step 4: Drill Holes
Remove the controller and drill 4 holes in the marked locations. Use drill size #29 for #8 self tap-
ping screws.
3.3.5 Step 5: Secure Controller
Place the controller on the surface and align the mounting holes with the drilled holes in Step
3.3.4. Secure the controller in place using 4, #8 self tapping screws.
3.4 CONNECTIONS
+
12V/24V
Battery
12V/24VDC
Load (<20A)
e.g. Light
Light Switch “S1”
rated for 20A
Ground the Negative Terminal
of the battery as follows, if required by code:
• Ground to Earth Ground in shore installations
• Ground to Chassis Ground in Negative Grounded
mobile installations
Optional
Remote Battery
Temp Sensor
Model MSK-TS
120 VAC
Fuse F2 Fuse
F1
(30A)
Solar Panel
or Array
MSK-20A
+ –
NOTE: Maximum current on the Load
Terminals should be limited to 20A
12V/24V
Inverter
Temp.
Sensor COM
Fig 3.2: Wiring Diagram
SECTION 3 | Installation

10 | SAMLEX AMERICA INC.
SECTION 3 | Installation
3.4.1 Step1: Battery Connection
WARNING!
RISK OF EXPLOSION OR FIRE! NEVER SHORT CIRCUIT BATTERY POSITIVE (+)
AND NEGATIVE (-).
MISE EN GARDE!
RISQUE D'EXPLOSION OU D'INCENDIE! NE COURT-CIRCUITEZ JAMAIS LA
BATTERIE POSITIF (+) ET NÉGATIF (-).
Refer to Fig 3.2
Before the battery is connected:
• Make sure that battery voltage is greater than 8V so as to start up the controller.
• For 24V systems, make sure the battery voltage is not less than 18V to ensure that battery
system voltage is correctly sensed as 24V.
• Battery system voltage will be sensed automatically when the controller starts up for the rst time.
• A 30A fuse (F1) is required to protect the cable run from the battery to the charge controller
against short circuit. Install the fuse not more than 7" from the battery Positive terminal. Do not
insert the fuse at this time.
3.4.2 Step 2: Load Connection through Load Terminals (Limited to 20A)
Refer to Fig 3.2
The Load Terminals of the controller can be connected to such electrical devices as lights and other
devices with load current of up to 20A. Controller provides power to the load(s) through the battery.
When load(s) are fed from the Load Terminals, the controller will provide the following protec-
tions on the load side:
Protect the battery as follows:
- Battery Low Voltage Alarm (≤12V/24V): Battery Status LED (2, Fig 2.1) will be steady ORANGE.
Output will still be available at Load Terminals. This condition will auto reset at 12.2 / 24.4V
WARNING!
CURRENT OUTPUT ON THE LOAD TERMINALS IS LIMITED TO A MAXIMUM OF 20A.
IF HEAVIER LOADS DRAWING MORE THAN 20A LIKE INVERTER ETC. ARE REQUIRED
TO BE POWERED, CONNECT THEM DIRECTLY TO THE BATTERY THROUGH APPROPRI-
ATE FUSE "F2" THAT SHOULD MATCH THE DC INPUT CURRENT OF THE INVERTER.
THIS FUSE SHOULD ALSO BE INSTALLED WITHIN 7" OF THE BATTERY (+) TERMINAL.

10 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 11
MISE EN GARDE!
LA SORTIE DE COURANT SUR LES BORNES DE CHARGE EST LIMITÉE À UN
MAXIMUM DE 20A. SI DES CHARGES PLUS LOURDES TIRENT PLUS DE 20A
COMME UN ONDULEUR, ETC. DOIVENT ÊTRE ALIMENTÉS, CONNECTEZ-LES
DIRECTEMENT À LA BATTERIE VIA LE FUSIBLE APPROPRIÉ «F2» QUI DOIT
CORRESPONDRE AU COURANT D'ENTRÉE CC DE L'ONDULEUR. CE FUSIBLE DOIT
ÉGALEMENT ÊTRE INSTALLÉ À MOINS DE 7 "DE LA BORNE (+) DE LA BATTERIE.
- Battery Over Voltage (≥16V/32V):
• Battery Status LED (2, Fig 2.1) will be fast blinking GREEN (4 Hz)
• Load will be disconnected. This condition will be automatically reset at 15.0 / 30.0V.
- Low Voltage - Load Disconnect (≤11.1V/22.2V): Battery Status LED (2, Fig 2.1) will be steady
RED. Output to Load Terminals will be disconnected. This condition will be auto reset at 12.6/ 25.2V
Protect the load as follows:
- Overload or short circuit in the load connected to the Load Terminals: Output
to Load Terminals will be disconnected (Refer to Sections 5.1.4 & 5.1.5 for details)
Connect the Positive (+) and Negative (-) of load(s) to controller Load Terminals as shown in Fig 3.2.
3.4.3 Step 3: Solar Panel / Array Connection
WARNING!
RISK OF ELECTRIC SHOCK! EXERCISE CAUTION WHEN HANDLING SOLAR
CONNECTIONS. HIGH VOLTAGE OUTPUT FROM THE SOLAR PANEL(S)/ARRAY
MAY CAUSE SHOCK OR INJURY. COVER THE SOLAR PANEL(S)/ARRAY FROM THE
SUN BEFORE INSTALLING SOLAR WIRING.
MISE EN GARDE!
RISQUE DE CHOC ELECTRIQUE! FAITES PREUVE DE PRUDENCE LORS DE LA
MANIPULATION DE L'ÉNERGIE SOLAIRE CONNEXIONS. LA SORTIE HAUTE
TENSION DES PANNEAUX PHOTOVOLTAÏQUES PEUT PROVOQUER DES
CHOCS OU DES BLESSURES. COUVREZ LES PANNEAUX PHOTOVOLTAÏQUES
DU SOLEIL AVANT D'INSTALLER LE CÂBLAGE SOLAIRE.
The controller can accept 12V (36 cell) or 24V nominal (72 cell) Solar panel(s) with maximum
Open Circuit Voltage of up to 50V. Continuous voltage > 50V will damage the input section of
the controller.
3.4.4 Step 4: Battery Temperature Sensing and Compensation
3.4.4.1 Lead Acid Batteries have a Negative “Temperature Coefcient” i.e. the battery charging /
discharging voltages will (i) rise due to fall in electrolyte temperature resulting in under charging
if charger voltage is not compensated and (ii) fall due to rise in electrolyte temperature resulting
SECTION 3 | Installation

12 | SAMLEX AMERICA INC.
in overcharging if charger voltage is not compensated. Battery manufacturers, therefore, specify
battery charging / discharging voltages and capacities of Lead Acid Batteries at Standard Room
Temperature of 25º C.
3.4.4.2 When the battery electrolyte temperature varies from the Standard Room Temperature
of 25º C, the values of charging / discharging voltages will be compensated based on the actual
battery electrolyte temperature using parameter called “Battery Temperature Compensation
Coefcient”. In this controller, this parameter is set at -3mV/ºC/Cell i.e. (i) -18mV/ºC for 6-cell,
12V battery or (ii) -36mV/ºC for 12-cell, 24V battery.
3.4.4.3 The controller has built-in Temperature Sensor for indirect and approximate sensing of
battery temperature. For this, the controller has to be placed very close to the battery. This built-
in sensor is the default sensor if the optional Remote Battery Sensor Model MSK-TS is NOT being
used.
3.4.4.4 For accurate sensing of the temperature of battery electrolyte, it is recommended that
the optional Remote Battery Temperature Sensor Model No. MSK-TS is used. This Temperature
Sensor comes with 3M/10ft cable with a cylindrical Temperature Sensor Head for battery end and
2-pole Female Connector for the controller end. Install this sensor as follows:
• Attach the Cylindrical Sensor Head half way down the vertical side of the warmest part of
the battery in the battery bank so that the sensor picks up the temperature of the electrolyte.
Use 1 mil “PVC Pipe Wrap Tape” to tape the sensor to the battery (pre-clean the battery
surface with Rubbing Alcohol prior to placing the tape)
• Insert the 2-pole Female Connector into the Jack marked “Temp Sensor” (8 in Fig 2.1)
3.4.4.5 When the optional Remote Battery Temperature Sensor Model MSK-TS is plugged into
the controller, the internal Temperature Sensor (Section 3.4.4.3 above) will automatically be
disabled.
3.4.5 Step 5: Install Fuse
Install 30A fuse "F1" in the battery circuit, (not included) as shown in Fig 3.2.
3.4.6 Step 6: Conrm Power ON
When battery power is applied, the controller will start operating. Refer to Table 4.1 under
Section 4.7 for operational information through the Solar Panel / Battery / Status LEDs (1, 2 & 3
in Fig 2.1).
SECTION 3 | Installation

12 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 13
SECTION 4 | Operation
4.1 PRINCIPLE OF OPERATION OF SOLAR CHARGING WITH SERIES
TYPE PULSE WIDTH MODULATION (PWM) CONTROL
The design and operation of MSK-20A is based on Series Type PWM (Pulse Width Modulation)
control at PWM frequency of 25 Hz.
4.2 PWM EXPLANATION
The output of the Solar Panel(s)/ Array is connected to the battery in series with a Mosfet Switch
inside the controller. A Micro-controller controls the ON / OFF operation of the Mosfet Switch to
control the charging current and consequently, the State of Charge of the battery.
A Solar Panel is a current source that outputs constant current equal to its Short Circuit Current
(Isc) over a wide voltage range (provided Irradiance Level, Spectrum and Cell Temperature remain
constant). For example, at STC, a typical 12V nominal, 45W PV Panel may provide constant Short
Circuit Current (Isc) of around 3A over voltage range from 0V to around 15V.
PWM consists of repetitive cycles of controlled duration of ON and OFF states of the Series
Connected Mosfet Switch inside the controller. The sum of ON and OFF times of one cycle is
called the Pulse Period. In PWM control, the duration of the Pulse Width (ON time) is varied
(modulated) and is dened by “Duty Cycle” which is the ratio of the “ON Time” to the “Pulse
Period ”. Duty Cycle is normally specied in %. Thus, 0% Duty Cycle will mean that the switch is
constantly OFF (will output 0A) and 100% Duty Cycle will mean that the switch is constantly ON
and will output the full instantaneous Short Circuit Current “Isc” of the panel. For Duty Cycles >
0% and < 100%, the switch will alternate between ON and OFF states in a controlled manner
in every cycle and will output variable average current within a range of 0A to the full Short
Circuit Current Isc. Thus, through PWM control, the Mosfet Switch inside the controller converts
constant Short Circuit Current (Isc) of the Solar Panel(s) to controlled average charging current
at its output by varying the Duty Cycle. The average value of the charging current is equal to the
instantaneous input value of Short Circuit Current (Isc) of the panel multiplied by the Duty Cycle.
4.3 PWM CHARGING IN MSK-20A
Battery charging is a current based process. Current fed to the battery results in re-charging
of the cells and consequent rise in battery voltage. Controlling the current will control battery
voltage. For 100% return of capacity, and for prevention of excessive gassing and sulfation,
the battery charging voltage is required to be controlled at the specied Voltage Regulation Set
Points for Absorption and, Float Charging Stages for different battery types. Battery can, thus, be
charged at the specied Voltage Regulation Set Points by PWM of the charging current through
control of Duty Cycle as explained above. The controller checks the battery voltage and updates
the Duty Cycle regularly at a very fast rate. The Duty Cycle is proportional to the difference be-
tween the sensed battery voltage and the Voltage Regulation Set Point. Once the specied Volt-
age Regulation Set Point is reached, it is kept steady - rise in voltage is compensated by reducing
the average current by reducing the Duty Cycle and fall in voltage is compensated by raising the
average current by raising the Duty Cycle. These fast updates on battery voltage measurements
and Duty Cycle corrections ensure charging of the battery at the specied Voltage Regulation Set
Point with minimum voltage deviation.

14 | SAMLEX AMERICA INC.
SECTION 4 | Operation
4.3.1 Optimum PWM Frequency
The PWM frequency can range from tens of Hz to around 1000 Hz. At higher frequencies, the
time period between the cycles is lesser and is not sufcient to complete the electro-chemical
reactions. At lower frequencies, the rise times of the charging pulses are lower which results in
higher gas bubble formation resulting in lowering of active surface area and increase of internal
impedance. In MSK-20A, frequency of 25 Hz is used for optimum charging performance.
4.3.2 Benets of pulsing nature of charging current during PWM
During PWM voltage regulated stages of Absorption, and Float Duty Cycle is lower and the
charging current is in the form of pulses. Pulsing charging current allows some Oxygen and
Hydrogen generated during charging chemical reactions to be chemically combined again and
then absorbed. This eliminates concentration polarization and ohm polarization and reduces the
internal pressure of the battery. Consequently, charging process is smoother and more capacity is
returned to the battery. Further, pulsing current provides more time to react, which reduces the
gassing volume and improves the absorption rate of charging current.
4.4 CHARGING PROFILES
The controller has been set for the following 2 Charging Proles:
(a) 3-Stage Normal Prole: See Fig 4.1 & Section 4.4.1 for details
DAY
TIME
Vf
Va
Fig 4.1 3-Stage Normal Prole
Bulk Absorption Float
BATTERY VOLTAGE
10
11
12
13
14
15
16
20
22
24
26
28
30
32
12V
24V
STAGE 1
BULK
STAGE 2
ABSORPTION
STAGE 3
FLOAT
NIGHT NIGHT
2 Hrs
LEGEND FOR FIG 4.1
Va - Absorption Stage Voltage
Vf - Float Stage Voltage
NOTE: Voltages represented by the Charging Curves are based on battery voltages
Figs 4.1 Charging Prole
4.4.1 3-Stage Normal Charging Prole
Please refer to Fig 4.1
This charging cycle is carried out for normal day to day charging. Charging is sequential: Stage
1: Bulk Stage (Maximum available Current from the solar panel / solar array = Instantaneous
Short Circuit Current “Isc” of the solar panel / solar array) Stage 2: Absorption Stage (Con-
stant Voltage) Stage 3: Float Stage (Constant Voltage).

14 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 15
SECTION 4 | Operation
4.4.1.1 Stage 1 - Bulk Stage
Please refer to Fig 4.1
This is almost a constant current stage. During this stage, the Mosfet Switch is kept at 100%
Duty Cycle (ON continuously) and hence, maximum current equal to the available instantaneous
Short Circuit Current "Isc" of the solar panel(s) / sola array is fed to the battery and the battery
voltage starts rising. When the voltage rises to the Absorption Voltage “Va”, the controller tran-
sitions to Absorption Stage. At the end of the Bulk Stage, the battery is charged to around 80%
capacity. The balance of 20% capacity is restored in the next Absorption Stage.
4.4.1.2 Stage 2 - Absorption Stage
Please refer to Fig 4.1
The controller enters this stage from the previous Bulk Stage when the battery voltage rises to the
Absorption Stage Voltage “Va” which is internally set as follows:
- “Va” for 12V battery: 14.4V for Sealed Lead Acid (AGM - Absorbed Glass Mat)
- “Va” for 24 V battery: 28.8V for Sealed Lead Acid (AGM - Absorbed Glass Mat)
This stage is timed for 2 Hrs - either continuous or cumulative.
This is a constant voltage stage and the Mosfet Switch operates under PWM control by feeding
pulsing Short Circuit Current “Isc” with constantly reducing Duty Cycle (< 100% to > 0%) /
average current to keep the battery voltage constant at the Absorption Stage Voltage “Va”. This
is an intentional, controlled over voltage condition for the battery for 2 Hrs. This is necessary to
return the balance 20% of the capacity. At this voltage, the battery starts gassing (evolution of
Hydrogen and Oxygen due to electrolysis of water in the electrolyte) and hence, it is necessary to
exit this stage as soon as 100% capacity is restored. If this over voltage condition is allowed to
continue after 100% recharging, the battery will be damaged due to effects of overcharging like
overheating, loss of water (Flooded Batteries), corrosion of the Positive plates and excessive build
up of pressure resulting in acid spillage due to opening of pressure activated relief valves (Sealed
Batteries). The balance of 20% of the battery capacity is restored in this stage. As the battery
capacity rises from 80% to 100%, the PWM control tapers the current by continuously reducing
the Duty Cycle from < 100% to > 0%.
Change over to the next Float Stage Voltage “Vf” (13.8V for 12 V battery and 27.6V for 24V
battery) is possible only after the battery voltage is held at the selected Absorption Stage Voltage
“Va” for continuous or cumulative period of 2 Hours. If Absorption Stage Voltage “Va” cannot be
maintained continuously / cumulatively for 2 Hr, transition to Float Stage WILL NOT take place.
4.4.1.3 Stage 3 - Float stage
Please refer to Fig 4.1
The controller enters this stage from the previous Absorption Stage after the battery voltage is held
at the selected Absorption Stage Voltage “Va” for continuous or cumulative period of 2 Hours.
This is also a constant voltage stage and the Mosfet Switch operates under PWM control by
feeding pulsing, instantaneous Short Circuit Current “Isc” with very low Duty Cycle of > 0%
to < 10% to keep the battery voltage constant at the Float Stage Voltage “Vf” (13.8V for 12V
battery and 27.6V for 24V battery). During this stage, the battery is 100% charged and a very
low “Trickle Charge” of around 0.1% of the Ah Capacity is required to be fed to the battery to
compensate for self-discharge. The battery can be left at this stage for prolonged period of time.

16 | SAMLEX AMERICA INC.
SECTION 4 | Operation
4.4.1.3.1 Automatic Exit from Float Stage to Absorption Stage
The charger will exit Float Stage and enter Absorption Stage (Section 4.4.1.2) automatically as
follows:
(i) During Float Stage, if the load current is more than the current supplied by the Solar Panel(s),
the battery voltage will drop. The battery voltage will also drop due to self discharge if there is
no sun for prolonged period of time or, if the Solar Pannel / Solar Array gets disconnected. If
the battery voltage drops to 13.2V for 12V battery or 26.4V for 24V battery, the Controller will
revert to Stage 2 - Absorption Stage (Section 4.4.1.2) or,
4.7 LED INDICATIONS
LED indications for operational status are shown at Table 4.1.
TABLE 4.1 LED INDICATIONS FOR OPERATIONAL STATUS
Location
of LED
(Fig 2.1) Function of LED
Color
of LED
LED Lighting
Pattern Operational Status
1
Solar Panel
Status LED Green On Steady Unit is on, but not charging due to
insufcient Solar Panel Power.
Green Slow Blinking (1Hz)Unit is charging
Green Fast Flashing (4Hz)Solar Panel, has been connected in reverse
polarity (See Section 5.1.3)
Green OFF
(i) Solar Panel Voltage is < 5V due to:
• Night time or,
• Solar Panel is disconnected or,
• Solar panel is shorted
2
Battery Status LED
Green On Steady Normal Battery Voltage: >12.4V / 24.8V
Green Slow Blinking (1Hz)Battery is fully charged
Green Fast Blinking (4Hz)
Battery over voltage: 16V / 32V
• Auto reset at 15.0V / 30.0V
(See Section 5.1.8)
Orange On Steady Battery low voltage warning: 12V / 24V
• Auto reset at 12.2V / 24.4V
Red On Steady
Battery low voltage 11.1 / 22.2V
• Auto reset at 12.6V / 25.2V
(See Section 5.1.10)
Red Slow Blinking (1Hz)
Battery over heated to >65°C. Charging
is stopped.
• Auto reset at <55°C
(See Section 5.1.11)
Table Continues on Next Page u

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TABLE 4.1 LED INDICATIONS FOR OPERATIONAL STATUS
Location
of LED
(Fig 2.1) Function of LED
Color
of LED
LED Lighting
Pattern Operational Status
3
Load Status LED
Red On Steady Battery power to Load Terminals is ON
Red Off Battery power to Load Terminals is OFF
Red Slow Flashing (1Hz)
Overload on the Load Terminals. Battery
power to Load Terminals is OFF
(See Section 5.1.4)
Red Fast Flashing (4Hz)
Short circuit at Load Terminals. Battery
power to Load Terminals is OFF
(See Section 5.1.5)
1,2,3
All 3 LED Indicators are blinking:
• Solar Panel / Array Status LED (1, Fig 2.1) = Blinks Green
• Battery Status LED (2, Fig 2.1) = Blinks Orange
• Load Status LED (3, Fig 2.1) = Blinks Red
- Internal hot spot is >85°C
• Input and output are disconnected
Auto reset at <75°C
(See Section 5.1.12)
1,2,3
All 3 LED Indicators are blinking:
• Solar Panel Status LED (1, Fig 2.1) = Blinks Green
• Battery Status LED (2, Fig 2.1) = Blinks Red
• Load Status LED (3, Fig 2.1) = Blinks Red
System voltage error. Battery voltage does
not match the controller voltage. Check
battery voltage is 12V/24V. Press Load
On/Off Button (4, Fig 2.1) to clear the
malfunction.
(See Section 5.1.14)
"System Voltage Error" due to:
1. Battery voltage is not within the range
of 8-32 VDC
4.8 LOAD ON/OFF CONTROL
When the controller is powered ON, press the Load On/Off Button (4, Fig 2.1) to toggle the load
ON and OFF. When load is ON, Load Status LED (3, Fig 2.1) will turn ON - RED.
Load On/Off Button (4, Fig 2.1) is also for clearing (i) "Load Overload" fault (Section 5.1.4),
(ii) "Load Short Circuit" fault (Section 5.1.5) and (iii) "System Voltage Error" (See Section 5.1.14)
4.9 BATTERY TEMPERATURE SENSING & COMPENSATION
Refer to Section 3.4.4 for details.
SECTION 4 | Operation

18 | SAMLEX AMERICA INC.
SECTION 5 | Protections & Troubleshooting
5.1 PROTECTIONS
5.1.1 Over Current of Solar Panel / Array
If the output current of the solar panel / array exceeds 20A rating of the controller, the charging
current will be limited to the rated current of 20A.
5.1.2 Short Circuit of Solar Panel / Array
If solar panel / array is short circuited, remove the short circuit to resume normal operation
automatically. The controller will not be damaged due to short circuit on the solar panel input side.
5.1.3 Reverse Polarity of Solar Panel / Array Input Connection
Fully protected against reverse polarity connection of solar panel / array. Solar Panel Status LED
(1, Fig 2.1) will fast blink Green @ 4Hz. The controller will not be damaged. Correct the polarity of
connection to resume normal operation.
5.1.4 Overload in the Load(s) Connected to Load Terminals
When the load is within the rated current of 20A, Load Status LED (3, Fig 2.1) will be steady RED.
When the load rises to ≥ 1.05 times (20.0A) for around 3 sec, overload protection is activated
as follows:
1. Load will be disconnected for 5 sec – Load Status LED (3, Fig 2.1) will slow blink
5 times @ 1Hz
2. Load will be reconnected – Load Status LED (3, Fig 2.1) will be steady
3. If overload ≥ 21.0A continues for 3 sec, the load will be disconnected for 10 sec and the
Load Status LED (3, Fig 2.1) will blink 10 times @ 1Hz
4. Load will be reconnected – Load Status LED (3, Fig 2.1) will be steady
5. If overload ≥ 21.0A continues for 3 sec, the load will be disconnected for 15 sec and the
Load Status LED (3, Fig 2.1) will slow blink 15 times @ 1Hz
6. Load will be reconnected – Load Status LED (3, Fig 2.1) will be steady
7. If overload ≥ 21.0A continues for 3 sec, the load will be disconnected for 20 sec and the
Load Status LED (3, Fig 2.1) will blink 20 times @ 1Hz
8. Load will be reconnected – Load Status LED (3, Fig 2.1) will be steady
9. If overload ≥ 21.0A continues for 3 sec, the load will be disconnected for 25 sec
10. Load will be reconnected – Load Status LED (3, Fig 2.1) will be steady
11. If overload ≥ 21.0A continues for 3 sec, the load will be disconnected permanently
and the Load Status LED (3, Fig 2.1) will slow blink continuously @ 1Hz
• To reset, remove overload and press the Load On/Off Button (4, Fig 2.1) for around 8 sec
5.1.5 Load Short Circuit
Short circuit condition is detected if the output current is ≥ 2 times (20A) momentarily. The pro-
tection is activated and reset as follows:
1. If load current ≥ 40A is detected momentarily, the load will be disconnected immediately
and the Red Load Status LED (3, Fig 2.1) will fast blink @ 4Hz for 5 sec
2. After 5 sec, the load will be reconnected. If short circuit condition continues, the load will
be disconnected immediately and the Red Load Status LED (3, Fig 2.1) will continue to fast
blink @ 4Hz for 10 sec.
3. After 10 sec., the load will be reconnected. If the short circuit condition continues, the
load will be disconnected immediately and the Red Load Status LED (3, Fig 2.1) will
continue to fast blink @ 4Hz for 15 sec.

18 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 19
4. After 15 sec., the load will be reconnected. If the short circuit condition continues, the
load will be disconnected immediately and the Red Load Status LED (3, Fig 2.1) will
continue to fast blink @ 4Hz for 20 sec.
5. After 20 sec., the load will be reconnected. If the short circuit condition continues, the
load will be disconnected immediately and the Red Load Status LED (3, Fig 2.1) will
continue to fast blink @ 4Hz for 25 sec.
6. After 25 sec., the load will be reconnected. If the short circuit condition continues, the
load will NOT be reset and the Red Load Status LED (3, Fig 2.1) will continue to
fast blink @ 4Hz until the short circuit condition is removed and manual reset is
carried out by pressing the Load On/Off Button (4, Fig 2.1) for 8 sec.
5.1.6 Battery Reverse Polarity
Fully protected against battery reverse polarity. The controller will not be damaged. Correct polar-
ity of wiring to resume normal operation.
5.1.7 Limiting Automatic Increase in Charging Stage Voltages Due Battery
Temperature Compensation (Parameter “Charging Limit Voltage”)
Refer to Section 3.4.4 on battery temperature sensing and compensation.
The values of parameters (i) “Absorption Stage Voltage” (Section 4.4.1.2), and (ii) “Float
Stage Voltage” (Section 4.4.1.3) are temperature compensated based on parameter “Battery
Temperature Compensation Coefcient” (18m/V°C for 12V battery and -36mV/°C for 24V bat-
tery). When the battery temperature falls below 25°C, the above Absorption Stage / Float Stage
Voltages will be compensated (raised) automatically. Unlimited automatic raising of the values of
these voltages due to battery temperature falling below 25°C is controlled by parameter called
“Charging Limit Voltage” which limits the rise of these voltages to 15.0V for 12V battery and
30.0V for 24V battery
5.1.8 Battery Over Voltage
At 16V/32V battery voltage, charging will be stopped. Battery Status LED (2, Fig 2.1) will be fast
blinking Green @ 4Hz. Automatic reset at 15V/30V.
5.1.9 Limiting Automatic Lowering of “Low Voltage Disconnect” Threshold
During Battery Temperature Compensation (Parameter “Discharging Limit
Voltage”)
Refer to Section 3.4.4 on battery temperature sensing and compensation
The threshold of parameter “Low Voltage Disconnect” (11.1V for 12V battery and 22.2V for
24V battery) is temperature compensated based on parameter “Battery Temperature Compensa-
tion Coefcient” (18mV/°C for 12V battery and -36mV/°C for 24V battery). When the battery
temperature rises above 25°C, parameter “Low Voltage Disconnect” will be compensated
(lowered) automatically. Unlimited automatic lowering of the value of this parameter due to
battery temperature rising above 25°C is controlled by parameter called “Discharging Limit Volt-
age” which limits the value of this parameter to value of 10.6V for 12V battery and 21.2V for
24V battery
SECTION 5 | Protections & Troubleshooting

20 | SAMLEX AMERICA INC.
SECTION 5 | Protections & Troubleshooting
5.1.10 Low Voltage - Load Disconnect
At battery voltage of 11.1/ 22.2V, the load connected to Load Terminals (6A, 6B in Fig 2.1) will be
disconnected. Battery Status LED (2, Fig 2.1) will be Steady Red. Automatic reset at 12.6/25.2V.
(NOTE: Loads directly connected to the battery will continue to discharge the battery.)
5.1.11 Over Temperature Protection – Battery
If the battery temperature exceeds 65°C, battery charging is stopped. Battery Status LED (2, Fig 2.1)
will slow blink Green @ 1Hz. Automatic reset at < 55°C.
NOTE: For this protection, optional Battery Temperature Sensor MSK-TS will be required to
be connected (See Section 3.4.4)
5.1.12 Over Temperature Protection – Controller
If the temperature of the controller’s heat sink exceeds 85°C, the input and output will be dis-
connected. The following 3 LEDs will blink:
• Solar Panel Status LED (1, Fig 2.1) will blink Green
• Battery Status LED (2, Fig 2.1) will blink Orange
• Load Status LED (3, Fig 2.1) will blink Red
Input and Output connections will be restored at 75°C
5.1.13 Damaged Temperature Sensor
If the optional external battery temperature sensor Model MSK-TS (Section 3.4.4) is short-circuit-
ed or damaged, the controller will charge or discharge at the default temperature of 25°C.
5.1.14 System Voltage Error
If the battery voltage does not match the Controller's Battery Voltage specications of 8-32V,
"System Error Voltage" will be indicated (See Table 4.1 under Section 4.7). Check battery voltage
is 12V / 24V. Press Load On/Off Button (4, Fig 2) to clear the fault.
Ensure that the battery voltage is within the acceptable range of 8-32V. Press Load On/Off But-
ton (4, Fig 2.1) to clear the fault.
5.1.15 High Voltage Transients
Battery is protected against high voltage transients. In lightning prone areas, additional external
lightning protection is recommended.