Mastervolt SCM20 PWM User manual

SOLAR CHARGE MASTER
SCM20 PWM / SCM40 PWM
PWM CONTROLLED PV BATTERY CHARGER
EN USER’S AND INSTALLATION MANUAL
NL, DE, FR, ES https://www.mastervolt.com/products/solar-charge-controllers
10000014327/02

2 EN / SCM20 & SCM40 PWM User’s Manual
OVERVIEW
1. MENU button
2. OK button
3. LCD-display
4. Casing
5. Heatsink
6. PV input
7. Battery connection
8. Load output
9. Temperature sensor jack
10. Identification label (rear side)
Figure 1: Overview
1
2
3
5
6
4
8
79
10

EN / SCM20 & SCM40 PWM User’s Manual 3
TABLE OF CONTENTS:
1GENERAL INFORMATION..............................................................................................................................................4
1.1 Use of this manual.............................................................................................................................................. 4
1.2 Validity of this manual......................................................................................................................................... 4
1.3 Use of pictograms............................................................................................................................................... 4
1.4 Identification label............................................................................................................................................... 4
1.5 Liability ............................................................................................................................................................... 4
2OPERATION....................................................................................................................................................................5
2.1 General............................................................................................................................................................... 5
2.2 Maintenance....................................................................................................................................................... 5
2.3 Three step charge algorithm............................................................................................................................... 5
2.4 LCD Display ....................................................................................................................................................... 6
2.5 Monitoring........................................................................................................................................................... 6
2.6 Configuration ...................................................................................................................................................... 7
2.6.1 Low voltage disconnect function........................................................................................................ 8
2.6.2 Battery type ....................................................................................................................................... 8
2.6.3 Load mode......................................................................................................................................... 8
3INSTALLATION...............................................................................................................................................................9
3.1 Unpacking .......................................................................................................................................................... 9
3.2 Environment ....................................................................................................................................................... 9
3.3 Wiring and fuses................................................................................................................................................. 9
3.4 Specifications of the PV array .......................................................................................................................... 10
3.5 Connection of loads.......................................................................................................................................... 10
3.5.1 Load connected to the Load output ................................................................................................. 10
3.5.2 Load connected to the battery ......................................................................................................... 10
3.6 Things you need............................................................................................................................................... 10
3.7 Connection ....................................................................................................................................................... 12
3.7.1 General............................................................................................................................................ 12
3.7.2 Installation step by step ................................................................................................................... 12
3.8 Commissioning after installation....................................................................................................................... 13
3.9 Decommissioning ............................................................................................................................................. 13
3.10 Storage and transportation ............................................................................................................................... 13
3.11 Re-installation................................................................................................................................................... 13
3.12 Correct disposal of this product ........................................................................................................................ 13
4TROUBLE SHOOTING..................................................................................................................................................14
5TECHNICAL DATA........................................................................................................................................................15
5.1 Specifications ................................................................................................................................................... 15
5.2 Dimensions....................................................................................................................................................... 16
5.3 Ordering information......................................................................................................................................... 16

4 EN / SCM20 & SCM40 PWM User’s Manual
1 GENERAL INFORMATION
1.1 USE OF THIS MANUAL
This manual serves as a guideline for the safe and
effective operation, maintenance and possible correction of
minor malfunctions of the “Solar ChargeMaster”
It is therefore obligatory that every person who works on or
with the Solar ChargeMaster must be completely familiar
with the contents of this manual and the Important Safety
Instructions, and that he/she carefully follows the
instructions contained herein.
Installation of, and work on the Solar ChargeMaster may
be carried out only by qualified, authorised and trained
personnel, consistent with the locally applicable standards
and taking into consideration the Important Safety
Instructions.
Copyright © 2018 Mastervolt. All rights reserved.
Reproduction, transfer, distribution or storage of part or all
of the contents in this document in any form without the
prior written permission of Mastervolt is prohibited.
1.2 VALIDITY OF THIS MANUAL
All of the specifications, provisions and instructions
contained in this manual apply solely to standard versions
of the Solar ChargeMaster delivered by Mastervolt.
This manual is only valid for the following models:
Part number Model
131822000 ChargeMaster “SCM20 PWM”
131822000 ChargeMaster “SCM40 PWM”
These models are mentioned as “Solar ChargeMaster”
further in this manual.
1.3 USE OF PICTOGRAMS
Safety instructions and warnings are marked in this manual
and on the product by the following pictograms:
A procedure, circumstance, etc which deserves
extra attention.
CAUTION!
Special information, commands and prohibitions
in order to prevent damage.
WARNING
A WARNING refers to possible injury to the user
or installer or significant material damage to the
Soladin if the installer / user does not (carefully)
follow the stated procedures.
Read this manual before installation and use
This product has been declared conform the EC
directives and standards.
Degree of protection: IP23. The product is
protected against touch by fingers and water
spray < 60 degrees from vertical.
1.4 IDENTIFICATION LABEL
Figure 2: Identification label
The identification label is located at the rear side of the
Solar ChargeMaster (see Figure 2). Important technical
information required for service, maintenance & secondary
delivery of parts can be derived from the identification
label.
CAUTION!
Never remove the identification label.
1.5 LIABILITY
Mastervolt can accept no liability for:
consequential damage due to use of the Solar
ChargeMaster;
possible errors in the manuals and their results.
Part no: 131824000
Type: SCM40 PWM
PV-input: 36cells, 28Vmax, 4 @ 12Vbat
72cells, 55Vmax, 4 @ 24Vbat
Output: 14.25 / 28.5VDC, 40A
0Amax
0Amax
Snijdersbergweg 93, 1105AN Amsterdam, The Netherlands
IP23
Designed by Mastervolt
Manufactured in PRC
Serial no: J821A0001
Serial number
J821A0001
Apparatus version “A”
Part number
IP23

EN / SCM20 & SCM40 PWM User’s Manual 5
2 OPERATION
2.1 GENERAL
The Mastervolt Solar ChargeMaster is a fully automatic
battery charger which converts power from photovoltaic
(PV) array to a regulated battery voltage. The Solar
ChargeMaster will automatically adjust itself to a 12V or a
24V system. Under normal circumstances the Solar
ChargeMaster remains switched on with the PV-array and
batteries connected.
If power from the PV array is sufficient, the Solar
Chargemaster will initiate the charging process.
WARNING
The Solar Chargemaster has no on/off switch.
Charging will be initiated as soon as power from
the PV-array becomes available.
The Load output of the Solar Chargemaster switches off if
one of the following fault conditions occurs: overload, short
circuit, overheating or under and over voltage. The Load
output switches on again after one minute if the Solar
Chargemaster recovers from these fault conditions.
CAUTION!
The Solar ChargeMaster is not protected
against:
Excessive overvoltage on the Solar input
Surges inducted by lightning.
2.2 MAINTENANCE
No specific maintenance to the Solar Chargemaster is
required. Examine your electrical installation on a regular
base, at least once a year. Defects such as loose
connections, burnt wiring etc. must be corrected
immediately.
If necessary, use a soft clean cloth to clean the casing of
the Solar Chargemaster. Do not use any liquids or
corrosive substances, such as solvents, alcohol, petrol or
abrasive components.
In the event of decommissioning, refer to section
3.9
2.3 THREE STEP CHARGE ALGORITHM
See Figure 3. Battery charging is accomplished in three
automatic stages: BULK, ABSORPTION and FLOAT.
Figure 3: Three step charge system
BULK: At this stage the charger delivers its maximum
current for quick charging from 0 to 80%
ABSORPTION: The charger has reached its maximum
charge voltage and the charge current will slowly
decrease until the battery is charged up to 100%.
FLOAT: This stage begins once the battery is fully
charged. The battery remains in fully charged state.
By installing the battery temperature sensor (not included;
see section 5.3 for ordering information) the charge
voltages are automatically adapted for deviating
temperatures.
Figure 4: Temperature compensated charging
See Figure 4. When the battery temperature is low, the
charge voltage increases. On the other hand, when the
battery temperature is high, the charge voltage is
decreased. Over charge and gassing are prevented this
way. This will extend the life of your batteries
12V 24V
battery temperature (°C)
charge voltage (V)

6 EN / SCM20 & SCM40 PWM User’s Manual
2.4 LCD DISPLAY
Use the MENU and OK button (Figure 1, items 1
and 2) to operate the Solar Chargemaster
Explanation of the symbols used on the screen:
Item Indication Meaning
PV Array Daytime, not
charging
Daytime, charging
Night
PV voltage, current
and Ah’s
Total Charged Ah
from the PV-array
Battery Battery capacity
Battery voltage
(programmable)
Battery current
Battery state of
charge (in %)
Temperature
Battery tyoe
(programmable)
Load Load voltage, current
and Ah (24hrs cycle)
The total discharge
Af of the load
Load mode
(programmable)
Load is off
Load is on
Fault Fault condition, see
section 4
2.5 MONITORING
There are three monitoring modes:
Automatic Scrolling Mode: the LCD-display is
automatically scrolling through a selection of screens.
Manual Scrolling Mode; Press OK shortly to scroll
through all screens manually.
Static Display Mode: Hold MENU and OK pressed
simultaneously for 1 second to lock the screen. Hold
MENU end OK pressed simultaneously for 1 second
again to return to the Automatic Scrolling Mode.
Below table shows the available screens.
(#) = not shown in Automatic Scrolling Mode
(!) = not relevant if the load is directly connected
to the battery; see section 3.5.
= you can enter the configuration mode from
this screen; see section 2.6.
Screen Meaning
Voltage at the PV input.
Current of the PV array.
(#) Charged Ah.
(#)Total Charged Ah from
the PV-array.
Battery voltage
See section 2.6 for
configuration of the Low
voltage disconnect function.
(!) Battery current.
Positive = charging.
Negative = discharging.
(!) State of charge (available
energy in %) of the battery.
Temperature of the battery in
°C. Only shown if battery
temperature sensor is
connected.

EN / SCM20 & SCM40 PWM User’s Manual 7
Screen Meaning
(#) Battery type.
See section 2.6 to change
the Battery type settings
(!) Voltage at the Load
output.
(!) Load current.
(#)(!) Discharged Ah from the
battery.
(#)(!)Total discharged Ah
from the battery.
(#)(!) Status of the load
mode.
See section 2.6 for
explanation and
configuration of the Load
mode settings
2.6 CONFIGURATION
CAUTION!
Invalid settings of the Solar ChargeMaster can
cause serious damage to your batteries and/or
the connected load! Adjustments of settings may
be undertaken by authorised personnel only.
If your Solar Chargemaster is not new, you have
to take into account that former users may have
changed the settings.
When the symbol is shown on the screen (see section
2.5), you can enter the Configuration mode:
Hold MENU pressed for 1 sec. until the symbol starts
blinking
Change a setting:
Shortly press OK until the desired setting is shown
Save setting and exit the configuration mode:
Press MENU shortly
Exit the Configuration mode without saving setting:
Wait for 30 seconds.

8 EN / SCM20 & SCM40 PWM User’s Manual
2.6.1 Low voltage disconnect function
There are two ways to protect the battery from too deep
discharges:
Static: the Load output switches off if the battery
voltage drops below the Disconnect threshold voltage.
Dynamic: the Load output switches off depending on
both battery voltage and load current.
The Load output switches on again if the battery voltage
rises above the Reconnect threshold value.
The Low voltage disconnect function can only be used if
the load is connected to the Load output (see section 3.5)
Static Low voltage disconnect function:
Indication Disconnect
threshold Reconnect threshold
10.8 / 21.6 10.8V / 21.6V 11.6 V / 23.2V
10.9 / 21.8 10.9V / 21.8V 11.7 V / 23.4V
11.0 / 22.0 11.0V / 22.0V 11.8 V / 23.6V
11.1 / 22.2 11.1V / 22.2V 11.9 V / 23.8V
11.2 / 22.4 11.2V / 22.4V 12.0 V / 24.0V
11.3 / 22.6 11.3V / 22.6V 12.1 V / 24.2V
11.4 / 22.8 11.4V / 22.8V 12.2 V / 24.4V
11.5 / 23.0 11.5V / 23.0V 12.3 V / 24.6V
11.6 / 23.2 11.6V / 23.2V 12.4 V / 24.8V
11.7 / 23.4 11.7V / 23.4V 12.5 V / 25.0V
11.8 / 23.6 11.8V / 23.6V 12.6 V / 25.2V
Dynamic Low voltage disconnect function:
Indication Disconnect threshold Reconnect
threshold
at full load at no load
11.0V
22.0V
11.6V
23.2V
12.4 V
24.8V
11.1V
22.2V
11.6V
23.2V
12.5 V
25.0V
11.2V
22.4V
11.6V
23.2V
12.6 V
25.2V
11.4V
22.8V
11.6V
23.2V
12.7 V
25.4V
11.6V
23.2V
11.6V
23.2V
12.8 V
25.6V
2.6.2 Battery type
Indication Battery type
Gel
Flooded (liquid)
AGM
2.6.3 Load mode
Indication Load mode
Always on Mode: the load output
is always switched on
Dusk to Dawn Mode: the load
output is switched on between
sunset and sunrise.
PV input threshold voltage:
5.0/10.0V
Evening Mode: The load output
will be switched on for 2~9 hours
after sunset.
Manual Mode. The load output
can be switched on and off
manually by pressing MENU
shortly.
NOTES:
You can test the operation of the Load output manually
by holding MENU pressed for 3 seconds. Press MENU
again to switch off the load again or the load will switch
off automatically after 1 minute.
If the Manual Load Mode is selected (“USE”), you can
switch on and off the Load output manually by pressing
MENU shortly. In this case the protections against fault
conditions for overload, short circuit, overheating or
under and over voltage will be ignored!

EN / SCM20 & SCM40 PWM User’s Manual 9
3 INSTALLATION
During installation commissioning and maintenance of the
Solar ChargeMaster, the Important Safety Instructions are
applicable at all times.
3.1 UNPACKING
The delivery includes the following items:
Solar Chargemaster;
This User’s manual
Important Safety Instructions
After unpacking, check the contents for possible damage.
Do not use the product if it is damaged. If in doubt, contact
your supplier.
3.2 ENVIRONMENT
Obey the following stipulations during installation:
The Solar Chargemaster is designed for indoor use
only.
Ambient operating temperature: -20°C ... 50°C / -4°F …
122°F (power de-rating above 40°C / 104°F to
decrease the internal temperature).
Humidity: 5-95%, non-condensing.
The Solar ChargeMaster must be mounted to a vertical,
solid and heat-resistant surface, with the connecting
cables downwards.
Do not expose the Solar Chargemaster to excessive
dust, aggressive environments, ammonia or salt.
Make sure that the hot air that is developed during
operation can be discharged. The Solar Chargemaster
must be mounted in such a way that obstruction of the
airflow along the heatsink on the backside of the casing
will be prevented.
No objects must be located within a distance of 20 cm /
8 inch around the Solar Chargemaster.
Do not locate the Solar Chargemaster in the same
compartment as the batteries.
Do not install the Solar Chargemaster straight above
the batteries because of possible corrosive sulphur
fumes.
Although the Solar Chargemaster fully complies with all
applicable EMC limits, it may still cause harmful
interference to radio communication equipment. If such
interference appears, it is recommended to increase the
separation between the Solar Chargemaster and the
equipment, to relocate the receiving antenna or to
connect the equipment to a circuit different from that to
which the Solar Chargemaster is connected.
3.3 WIRING AND FUSES
WARNING
The wire and fuse sizes stated in this manual
are given as example only. Prescribed wire and
fuse sizes may be different due to local
applicable regulations and standards.
Keep in mind that high current will pass through the DC
wiring. Keep the cable length as short as possible, this will
keep the system efficiency as high as possible. The
recommended minimum cross sections of the wiring are:
Model Minimum DC Cable cross section
<2m / 6ft length 2 - 4m / 6 - 12ft
SCM20 PWM 6mm² / 8AWG 10mm² / 6AWG
SCM40 PWM 10mm² / 6AWG 16mm² / 4AWG
Use boot lace ferrules on the wire ends. These ferrules
must be crimped with a proper crimping tool.
Use the following wire colours for DC wiring:
Wire colour Meaning Connect to:
Red Positive + (POS)
Black Negative – (NEG)
Lay the positive and negative cables next to each other to
limit the electromagnetic field around the cables. The
negative battery cable should be connected directly to the
negative post of the battery bank or the ground side of a
current shunt. Do not use the chassis frame as the
negative conductor. Tighten securely. The positive battery
cable must be fused and connected to the positive post of
the battery bank.
The recommended DC fuses are:
Model Battery fuse Load fuse
SCM20 PWM 20A 20A
SCM40 PWM 40A 40A
See section 5.3 for ordering information

10 EN / SCM20 & SCM40 PWM User’s Manual
3.4 SPECIFICATIONS OF THE PV ARRAY
WARNING
When the PV array is exposed to light, it
supplies a DC voltage to the Solar
Chargemaster which can be dangerous to touch.
For this reason, use of an external DC-switch is
strongly recommended. Alternatively, before
attempting any maintenance or cleaning the PV-
array should be protected from light exposure,
e.g. by covering the PV modules.
CAUTION!
Do not connect Solar Chargemasters in parallel
on the side of the PV array.
The Solar ChargeMaster is appropriate for nominal 12V
and 24V solar systems. The table shows the number of
cells required for the nominal voltages.
Battery voltage U
NOM
= 12V
Model Panel type Max input
voltage Max input current
SCM20 PWM 36 cells 28V 20A
SCM40 PWM 36 cells 28V 40A
Battery voltage U
NOM
= 24V
Model Panel type Max input
voltage Max input current
SCM20 PWM 72 cells 55V 20A
SCM40 PWM 72 cells 55V 40A
CAUTION!
Never connect voltages higher than specified to
the PV-input, as this will cause permanent
damage to the Solar Chargemaster.
Configuration examples for PV-arrays consisting of
monocrystalline or polycrystalline PV-modules:
3.5 CONNECTION OF LOADS
Depending on the energy system in which the Solar
Chargemaster is used, there are two options to connect the
electrical load to the Solar Chargemaster:
To the Load output on the Solar Chargemaster, or
Directly to the battery.
3.5.1 Load connected to the Load output
See Figure 5 for a typical installation diagram. The Load
output is provided with a protection circuit that switches off
the connected load automatically in case of overload or if
the battery voltage is too low. This kind of installation is
typically used when the PV-modules are the only source of
electrical power to charge the battery.
3.5.2 Load connected to the battery
If the maximum load will exceed 20 Amps (SCM20 PWM),
40 Amps (SCM40 PWM) or if the battery will also be
charged by other energy sources, such as a battery
charger or an alternator, the electrical load shall be
connected to the battery directly. See Figure 6 for a typical
installation diagram. In this situation the battery is no longer
protected against too low battery voltages. Installation of
additional undervoltage protection circuits may be
necessary. See section 5.3 for ordering information
3.6 THINGS YOU NEED
Make sure you have all the parts you need to install the
Solar Chargemaster:
Solar Chargemaster (included);
Battery temperature sensor with cable and plug
(optional, not included; see section 5.3 for ordering
information);
DC cables to connect the Solar Chargemaster; see
section 3.3 for specifications;
DC-fuse holder with a DC-fuse, to be integrated in the
positive DC-cable to the battery; see section 3.3;
Screws / bolts (Ø 4mm max.) (with plugs) to mount the
Solar Chargemaster to a surface;
Batteries;
Appropriate and reliable cable terminals, strain reliefs,
battery terminals and boot lace ferrules.
We recommend as a minimum tool kit:
Phillips screw driver nr.2 or flat blade screw driver 5
mm to fix the DC-cables;
Tools to fix the screws / bolts with plugs to mount the
Solar Chargemaster to a surface;

EN / SCM20 & SCM40 PWM User’s Manual 11
Figure 5: Load connected to the Load output on the Solar Chargemaster
Figure 6: Load connected directly to the battery
Above schematics are to illustrate the general placement of the Solar Chargemaster in a circuit. They are not meant to provide
detailed wiring instructions for any particular electrical installation
Battery temperature sensor
BATTERY
Load
Battery fuse
Load fuse
PV-array
External DC-switch
(see section 3.4)
Battery temperature sensor
BATTERY
Load
Battery fuse
Load fuse
PV-array
External DC-switch
(see section 3.4)

12 EN / SCM20 & SCM40 PWM User’s Manual
3.7 CONNECTION
3.7.1 General
WARNING
Let installation work be done by a licensed
electrician.
All electrical systems must be disconnected from
any power source during the entire installation!
CAUTION!
Short circuiting or reversing DC polarity
may lead to damage to the Solar
Chargemaster, the cabling and/or the
terminal connections.
Follow all steps of the installation
instructions in order of succession as
described.
CAUTION!
Too-thin cables and/or loose connections can
cause dangerous overheating of the cables
and/or terminals. Therefore tighten all
connections well, in order to limit transition
resistance as far as possible. Use cables of the
correct size. Use additional strain reliefs to
prevent the transmission of stress to the screw
connectors.
CAUTION!
The negative connections of the Solar
ChargeMaster are common and therefore have
the same electrical potential. If grounding is
required, always do this on the negative wires.
Use one grounding point only.
NOTE:
If the battery temperature remains within 15-
25°C, connection of the battery temperature
sensor is optional
3.7.2 Installation step by step
1 Mark the position of the mounting spots. Then fix the
casing to the wall.
2 Fit boot lace ferrules to all DC-cables.
3 Integrate a fuse holder in the positive battery wire, but
do not place the fuse yet. Connect the wiring from the
Battery connection to the battery.
4 Optional: Attach the battery temperature sensor to the
casing the battery. Plug the temperature sensor cable
into the Temperature sensor jack.
WARNING
Risk of shock! When the PV array is exposed to
light, it supplies a dangerous DC voltage. See
section 3.4!
5 Connect the PV array.to the PV input.
6 Connect the wiring of the Load-output (see section
3.5). Integrate a fuse holder in the positive load wire,
but do not place the fuse yet.
7 Check all wiring: positive to +, negative to –. See also
Figures 5 and 6 for wiring examples. If OK, continue
with section 3.8 for commissioning of the Solar
ChargeMaster.

EN / SCM20 & SCM40 PWM User’s Manual 13
3.8 COMMISSIONING AFTER INSTALLATION
CAUTION!
Check the polarity of all wiring before
commissioning: positive connected to positive
(red cables), negative connected to negative
(black cables).
1 If all wiring is OK, place the DC-fuse between the Solar
Chargemaster and the battery
WARNING
When placing this fuse, a spark can occur,
caused by the capacitors used in the Solar
Chargemaster. This is particularly dangerous in
places with insufficient ventilation, due to the
gassing of the batteries an explosion can occur.
Avoid having flammable materials close by.
2 Then. place the DC-fuse between the Solar
Chargemaster and the load.
3 The Solar Chargemaster will initiate the charging
process if the voltage from the PV array is sufficient.
If the Solar Chargemaster does not switch on,
press MENU shortly.
4 Refer to section 2.6 for settings.
3.9 DECOMMISSIONING
To put the Solar ChargeMaster out of operation, follow
these instructions in order of succession:
1 Switch off all loads that are connected to the Solar
Chargemaster;
2 Disconnect the PV array by switching off the switch
between the PV-array and the Solar Chargemaster (or
protect the PV-array from light exposure, e.g. by
covering the PV modules);
3 Remove the DC-fuse between the Solar Chargemaster
and the battery;
4 Remove the DC-fuse between the Solar Chargemaster
and the load;
5 Check with a suitable voltage meter whether the
Battery connection and the LOAD output of the Solar
Chargemaster are voltage free;
6 Disconnect the negative cable to the PV array from the
terminal block of the Solar Chargemaster. Isolate the
core of the wire with insulating tape;
7 Do the same for the positive cable to the PV array;
8 Disconnect all other remaining wiring.
Now the Solar Chargemaster can be demounted in a safe
way.
3.10 STORAGE AND TRANSPORTATION
When not installed, store the Solar Chargemaster in the
original packing, in a dry and dust free environment.
Always use the original packing for transportation. Contact
your local Mastervolt Service Centre for further details if
you want to return the apparatus for repair.
3.11 RE-INSTALLATION
To reinstall the Solar Chargemaster, follow the instructions
as described in this chapter (chapter 3).
3.12 CORRECT DISPOSAL OF THIS PRODUCT
(Waste Electrical & Electronic Equipment)
This product is designed and manufactured
with high quality materials and components,
which can be recycled and reused. When
this crossed-out wheeled bin symbol is
attached to a product, it means the product is
covered by the European Directive 2012/19/EU.
Please be informed about the local separate collection
system for electrical and electronic products.
Please act according to your local rules and do not dispose
of your old products with your normal household waste.
The correct disposal of your old product will help prevent
potential negative consequences to the environment and
human health

14 EN / SCM20 & SCM40 PWM User’s Manual
4 TROUBLE SHOOTING
If you cannot solve a problem with the aid of this chapter, contact your local Mastervolt Service Centre. See
www.mastervolt.com/technical-support. Make sure you have the following information present if you have to contact your local
Mastervolt Service Center to solve a problem: Article and serial number; see section 1.4
Malfunction Possible cause What to do?
No display function Battery voltage is abnormal Check battery voltage. Battery voltage must be
10~15V for 12V systems or 20~30V for 24V
systems.
Reversed polarity of the Battery Check wiring to battery
No voltage at Load
output
Fault condition See below error codes E1 ~E5
Wrong setting of the Load mode Check settings of the Load mode (section 2.6)
Short circuit at Load output Switch off all loads, remove short circuit. Load
output will automatically resume after 1 minute.
Overload at Load output Reduce the connected load. Load output will
automatically resume after 1 minute.
Battery voltage is too low; see section 2.6
for configuration of the Low voltage
disconnect function.
Reduce load connected to the batteries and
charge batteries. Load output will automatically
resume after 1 minute.
Overcharge, battery voltage is too high
(>15.5/31.0V)
Check batteries. Check other charging systems.
Use the battery temperature sensor.
Over temperature Check cooling of the Solar Chargemaster
No battery charging
during daytime
Batteries are full Nothing.
No power from the PV-modules.. Check wiring to PV-modules. Check for loose
connections, short circuit or incorrect polarity
Damaged battery temperature sensor Check battery temperature sensor (if applied)
Output voltage too low,
charger supplies
maximum current
Load that is connected to the batteries is
larger than charger can supply.
Reduce load taken from the batteries.
Batteries not 100% charged Measure battery voltage. After some time this will
be higher.
Wrong battery type setting Check settings (see section 2.6).
Battery is discharged too
fast
Battery capacity reduced due to sulphation
or due to plate corrosion
Charge and recharge a few times, this might help.
Check battery and replace if necessary.
Too low charger capacity or battery
capacity or too high load
Check balance between charger capacity, battery
capacity and load
Batteries are too warm,
gassing
Defective battery (short circuit in cell) Check battery and replace if necessary.
Battery temperature too high Use the battery temperature sensor.
Charge current too high for battery Check specifications of battery for maximum
allowed charge current
Wrong battery type setting Check settings (see section 2.6).

EN / SCM20 & SCM40 PWM User’s Manual 15
5 TECHNICAL DATA
5.1 SPECIFICATIONS
Model SCM20 PWM SCM40 PWM
Article no.: 131822000 131824000
Nominal battery voltage (UNOM): 12V / 24 V (Auto recognition) 12V / 24 V (Auto recognition)
PV-INPUT @ UNOM = 12V @ UNOM = 24V @ UNOM = 12V @ UNOM = 24V
Typical number of cells: 36 cells 72 cells 36 cells 72 cells
Absolute maximum PV Voltage: 28VDC 55VDC 28VDC 55VDC
Maximum PV input current*: 20A 20A 40A 40A
Control: PWM
Dusk to dawn threshold voltage: 5V 10V 5V 10V
BATTERY OUTPUT @ UNOM = 12V @ UNOM = 24V @ UNOM = 12V @ UNOM = 24V
Maximum charge current (IMA
X
): 20A 20A 40A 40A
Charge voltage, Absorption: 14.4V 28.8V 14.4V 28.8V
Charge voltage, Float (flooded): 13.25V 26.5V 13.25V 26.5V
Charge voltage, Float (AGM / gel batteries): 13.8V 27.6V 13.8V 27.6V
Battery temperature compensation: –30 mV/°C –60 mV/°C –30 mV/°C –60 mV/°C
DC consumption (at night): 7mA 7mA 7mA 7mA
Battery voltage operating window: 10.0-15.0V 20.0-30.0V 10.0-15.0V 20.0-30.0V
Charge algorithm: Three step (Bulk, Absorption, Float)
Battery types*: Flooded, AGM, Gel
LOAD OUTPUT @ UNOM = 12V @ UNOM = 24V @ UNOM = 12V @ UNOM = 24V
Maximum output current: 20A 20A 40A 40A
Under voltage disconnect (adjustable**): 10.8~11.8V 21.6~23.6V 10.8~11.8V 21.6~23.6V
Under voltage reconnect (adjustable**): 11.6~12.6V 23.2~25.2V 11.6~12.6V 23.2~25.2V
GENERAL
Galvanic isolation between PV and battery: No, common negative conductor
Dimensions in mm [inch] (h x w x d): 96 x 189 x 53 mm [3.8 x 7.4 x 2.0 inch]; see also section 5.2
Weight: 480g
Operating Temperature Range: –20°C ≤TAMB ≤+50°C [–4°F ≤TAMB ≤122°F]
Full Power Temperature range: –20°C ≤TAMB ≤+40°C [–4°F ≤TAMB ≤104°F] (no power de-rating)
Non-operating Temperature range: –25°C ≤TAMB ≤+75°C [–13°F ≤TAMB ≤167°F] (storage temperature)
Relative Humidity: 5% to 95% non-condensing
Protections: Reversed polarity, output overload, output short circuit, overheating,
battery under voltage, battery over voltage
Protection degree: IP23
MasterBus connectivity: No
Load modes**: Always on, Dusk to Dawn, Evening, Manual
Terminals: Screw terminals, max. wire size 16mm2
* Short circuit current of the PV module ** Refer to section 2.6 for configuration
Specifications are subject to change without prior notice.

16 EN / SCM20 & SCM40 PWM User’s Manual
5.2 DIMENSIONS
Figure 7: Dimensions of the Solar ChargeMaster in mm [inches]
5.3 ORDERING INFORMATION
Part number Description
77049020 ANL Fuse 20A
77049040 ANL Fuse 40A
607006 ANL Fuse block
701 Battery switch 275A
41500500 Battery temperature sensor, incl. 6 meter / 19 ft cable
83200150 Battery Watch, Battery undervoltage protection circuit, 12V/24V, 100A continuous, 150A peak load
77020200 DC-Distribution 500.
The Mastervolt DC Distribution offers fused DC connections to install up to four different devices.
Mastervolt can offer a wide range of products for your electrical installation, including battery chargers, DC to AC Sine wave
inverters, AGM, gel and Li-ion batteries, DC distribution kits and many more.
See our website www.mastervolt.com for an extensive overview of all our products
187.8
177
4.70
0
17
47.5
78
81.5
95.4
51.6
MASTERVOLT, Snijdersbergweg 93, 1105 AN Amsterdam, The Netherlands, T: [phone], F: [phone], www.mastervolt.com