Magnum Dimensions MMSA Series User manual

Owner’s Manual
MMSA1012
Pure Sine Wave Inverter/Charger

© 2015 Sensata Technologies i
Thank you from all of us at Sensata Technologies for purchasing
this MMSA1012 inverter/charger. The MMSA1012 is a product under
the Magnum-Dimensions brand from Sensata Technologies. We
understand there are many purchasing options in the marketplace,
and are pleased that you have decided on a Magnum product. This
product was proudly assembled and tested in the United States in
our Everett, Washington, facility.
We are committed to providing quality products and services. We
hope your experience with us is pleasant and professional.
Disclaimer of Liability
The use of this manual and the conditions or methods of installation,
operation, use, and maintenance of the MMSA1012 inverter/charger
are beyond the control of Sensata Technologies. Therefore, this
company does not assume responsibility and expressly disclaims
liability for loss, damage, or expense whether direct, indirect,
consequential or incidental that may arise out of or be in any way
connected with such installation, operation, use, or maintenance.
Due to continuous improvements and product updates, the images
shown in this manual may not exactly match the unit purchased.
Restrictions on Use
The MMSA1012 inverter/charger may only be used in life support
devices and systems with the express written approval of Sensata
Technologies. Failure of this inverter can reasonably be expected to
cause failure of that life support device or system, or to affect the
safety or effectiveness of that device or system. If the MMSA1012
inverter fails, it is reasonable to assume the health of the user or
other persons may be endangered.
Copyright Notice
Copyright 2015 by Sensata Technologies. All rights reserved.
Permission to copy, distribute, and/or modify this document is
prohibited without written permission from Sensata.
Document Information
Description – MMSA1012 Owner’s Manual
Part Number and Revision – 64-0073 Rev A
Date Published – July 2015
This entire manual is available for download—with many of the
diagrams available in color—under the Library menu on our website.
Contact Information
Sensata Technologies
2211 West Casino Rd.
Everett, WA 98204
Phone: [phone] / Fax: [phone]
Web: www.Magnum-Dimensions.com

© 2015 Sensata Technologies
Safety Information
ii
Record the unit’s model and serial number in case you need to
provide this information in the future.
Model: Serial Number:
MMSA1012 BG
Conventions used in this Manual
Safety Symbols
To reduce the risk of electrical shock, fire, or other safety hazard, the
following safety symbols have been placed throughout this manual
to indicate dangerous and important safety instructions.
WARNING: This symbol indicates that failure to take a
specified action could result in physical harm to the user.
CAUTION: This symbol indicates that failure to take a
specified action could result in damage to the equipment.
Info: This symbol indicates information that emphasizes or
supplements important points of the main text.
IMPORTANT PRODUCT SAFETY INSTRUCTIONS
This manual contains important safety instructions that must be
followed during the installation and operation of this product. Read
all instructions and safety information before installing or using this
product.
• All electrical work must be performed in accordance with local,
state, and federal electrical codes.
• This product is designed for indoor/compartment installation.
DO NOT expose to rain, snow, moisture, or liquids of any type.
• Use insulated tools to reduce the chance of electrical shock or
accidental short circuits.
• Remove all jewelry such as rings, watches, bracelets, etc., when
installing or performing maintenance on the inverter.
• Always disconnect the batteries or energy source prior to
installing or performing maintenance on the inverter. Live power
may be present at more than one point since an inverter utilizes
both batteries and AC. Turning off the inverter may not reduce
this risk. As long as AC power is connected, it will pass through
the inverter regardless of the ON/OFF power switch setting.
• Always verify proper wiring prior to starting the inverter.
• Do not operate the inverter if it has been damaged.
• Do not dismantle the inverter; there are no user-serviceable
parts contained in this product. Attempting to service the unit
yourself could cause electrical shock. Internal capacitors remain
charged after all power is disconnected.

© 2015 Sensata Technologies
Safety Information
iii
BATTERY SAFETY INSTRUCTIONS
• Wear eye protection such as safety glasses when working with
batteries.
• Remove all jewelry such as rings, watches, bracelets, etc., when
installing or performing maintenance on the inverter.
• Never work alone. Always have someone near you when working
around batteries.
• Use proper lifting techniques when working with batteries.
• Never use old or untested batteries. Check each battery’s label
for age, type, and date code to ensure all batteries are identical.
• Batteries are sensitive to changes in temperature. Always install
batteries in a stable environment.
• Install batteries in a well-ventilated area. Batteries can produce
explosive gasses. For compartment or enclosure installations,
always vent batteries to the outside.
• Provide at least one inch of air space between batteries to provide
optimum cooling.
• Never smoke when in the vicinity of batteries.
• To prevent a spark at the battery and reduce the chance of
explosion, always connect the cables to the batteries first. Then
connect the cables to the inverter.
• Use insulated tools at all times.
• Always verify proper polarity and voltage before connecting the
batteries to the inverter.
• To reduce the chance of fire or explosion, do not short-circuit
the batteries.
• In the event of accidental exposure to battery acid, wash
thoroughly with soap and water. In the event of exposure to the
eyes, flood them for at least 15 minutes with running water and
seek immediate medical attention.
• Recycle old batteries.
SAVE THESE INSTRUCTIONS
• No AC or DC disconnects are provided as an integral part of this
inverter. Both AC and DC disconnects must be provided as part
of the system installation.
• No overcurrent protection for the battery supply is provided.
Overcurrent protection of the battery cables must be provided
as part of the system installation.
• No overcurrent protection for the AC output wiring is provided.
Overcurrent protection of the AC output wiring must be provided
as part of the system installation. Note: AC overcurrent
protection can be provided by the upstream breaker in the main
electrical panel.

© 2015 Sensata Technologies
iv
Table of Contents
1.0 Introduction.............................................................1
1.1 MMSA1012 Inverter/Charger ..................................... 1
1.2 How an Inverter/Charger Works................................. 1
1.3 Advantages of a Pure Sine Wave Inverter.................... 2
1.4 Appliances and Run Time .......................................... 2
1.5 Standard Features and Benefits ................................. 2
2.0 Installation ..............................................................8
2.1 Pre-Installation........................................................ 8
2.2 Locating and Mounting the Inverter...........................10
2.3 DC Wiring ..............................................................12
2.4 Connecting to the 3-Port Terminal Block.....................18
2.5 Remotes and Connections ........................................19
2.6 GFCI Breakers........................................................22
2.7 Inverter Warning Label ............................................22
2.8 Functional Test .......................................................23
3.0 Setup .....................................................................24
3.1 Adjusting DIP Switch Settings...................................24
4.0 Operation...............................................................30
4.1 MMSA Top Panel Features.........................................30
4.2 Operating Modes ....................................................34
4.3 Protection Circuitry Operation...................................37
4.4 Battery Temperature Sensor Operation ......................39
4.5 Summary of Inverter/DIP Switch Settings ..................40
5.0 Maintenance & Troubleshooting.............................41
5.1 Recommended Inverter & Battery Care......................41
5.2 Troubleshooting ......................................................41
5.3 Performing an Inverter Reset....................................44
5.4 Performing a Power Reset ........................................44
6.0 Specifications.........................................................45
Appendix A – Optional Equipment & Accessories...............46
Appendix B – Battery Information.....................................47
B-1 Battery Bank Sizing.................................................47
B-2 Battery Types .........................................................47
B-3 Battery Configuration ..............................................47
Appendix C – Warranty/Service Information.....................50
C-1 Warranty Information ..............................................50
C-2 How to Receive Repair Service..................................51

© 2015 Sensata Technologies v
List of Figures
Figure 1-1, MMSA1012 Inverter............................................... 1
Figure 1-2, Top Side Features.................................................. 4
Figure 1-3, Left Side Features ................................................. 4
Figure 1-4, Right Side Features ............................................... 5
Figure 1-5, Back Side Features ................................................ 5
Figure 1-6, Front Side Features ............................................... 6
Figure 1-7, MMSA1012 Inverter’s Anderson Connector................ 6
Figure 1-8, Battery Temperature Sensor ................................... 7
Figure 2-1, MMSA1012 Model Basic Installation Diagram............. 9
Figure 2-2, Approved Mounting Orientations.............................11
Figure 2-3, MMSA1012 Inverter Dimensions.............................12
Figure 2-4, DC Cable to Battery Terminals................................16
Figure 2-5, MMSA1012’s 3-Port Terminal Block .........................18
Figure 2-6, MMSA1012 Accessory Connections .........................21
Figure 2-7, Warning Label......................................................22
Figure 3-1, DIP Switch Summary............................................24
Figure 4-1, Top Panel Power Switch and LED Indicators..............30
Figure 4-2, Charge Status Indicators.......................................31
Figure 4-3, Automatic 4-Stage Charging Graph.........................36
Figure 4-4, BTS Temperature to Voltage Change .......................39
Figure 5-1, Resetting the Inverter...........................................44
Figure B-1, Series Battery Wiring............................................47
Figure B-2, Parallel Battery Wiring ..........................................48
Figure B-3, Series-Parallel Battery Wiring.................................48
Figure B-4, Battery Bank Wiring Examples ...............................49
List of Tables
Table 2-1, Recommended DC Wire/Overcurrent Device ..............14
Table 3-1, Battery Type to Charge Voltages ..............................28
Table 4-1, Charge Status LED Indicators ..................................31
Table 4-2, Inverter Battery Turn On/Off Levels..........................38
Table 4-3, MMSA Inverter/DIP Switch Settings..........................40
Table 5-1, Troubleshooting Guide ............................................42
Table 6-1, MMSA1012 Specifications........................................45

© 2015 Sensata Technologies
Introduction
1
1.0 Introduction
Congratulations on your purchase of an MMSA1012 inverter/charger.
This product is designed to be powerful, yet simple to use, and will
provide you with years of trouble-free use.
Please read this chapter to familiarize yourself with the features and
benefits of the MMSA1012 inverter/charger.
1.1 MMSA1012 Inverter/Charger
The MMSA1012 is a 1000-watt inverter/charger with a 20-amp
AC transfer relay and a 50-amp, 4-stage PFC charger. AC input is
provided by a standard 3 ft. plug-in power cord. Includes isolated
input/output neutrals, and a 15’ battery temperature sensor.
Figure 1-1, MMSA1012 Inverter
1.2 How an Inverter/Charger Works
An inverter takes direct current (DC) from your batteries and turns it
into alternating current (AC), like you use at home. The MMSA1012
inverter/charger also takes alternating current and transforms it
into direct current to recharge your batteries.
There are three modes of operation associated with this inverter:
• Inverter Mode: DC from the batteries is transformed into AC
for powering your vehicle.
• Standby Mode: The unit operates as a battery charger to
convert incoming AC power into DC power to recharge the
batteries while continuing to pass the incoming AC power
directly to the inverter’s output—to power any AC loads.

© 2015 Sensata Technologies
Introduction
2
1.2.1 Inverter Applications for Mobile Installations
In mobile applications, an inverter/charger provides power to the
AC loads using the energy stored in the batteries and recharges the
batteries when shorepower or an onboard generator is available.
1.3 Advantages of a Pure Sine Wave Inverter
Today’s inverters come in two basic output waveforms: modified
sine (which is actually a modified square wave) and pure sine wave.
Modified sine wave inverters approximate a pure sine waveform and
will run most appliances and electronics without any problems.
The output of a pure sine wave inverter is equal to, or in many
ways, better than the shorepower used in your home. Virtually any
electronic device will operate from a pure sine wave inverter. Motors
run cooler, microwaves usually cook faster, and clocks keep better
time just to name a few examples.
1.4 Appliances and Run Time
The MMSA1012 inverter/charger can power a wide range of
household appliances. As with any appliance using batteries for
power, there is a certain length of time that it can run—this is called
“run time”. Actual run time depends on several variables including
the size and the type of appliance, the type of batteries installed in
your application, as well as the battery’s capacity and age. Other
factors such as the battery’s state of charge and temperature can
also affect the length of time your appliances can run.
Depending on your inverter capacity, larger electrical appliances
can be used for short durations. However, loads that are used for
longer periods such as stoves or water heaters can quickly drain
your batteries and are not recommended for inverter applications.
All electrical appliances are rated by the amount of power they
consume. The rating is printed on the product’s nameplate label,
usually located on its chassis near the AC power cord. Even though it is
difficult to calculate exactly how long an inverter will run a particular
appliance, the best advice is trial and error. Your MMSA1012 inverter
has a built-in safeguard that automatically protects your batteries
from being over-discharged.
1.5 Standard Features and Benefits
The MMSA1012 inverter/charger converts 12-volt direct current
(VDC) power from your battery to 120-volt alternating current
(VAC) power. With the multi-stage battery charger feature, the
incoming AC power is optimized using Power Factor Correction
(PFC) technology to keep the inverter’s battery bank fully charged.
The MMSA1012 is designed to allow easy installation and use, and
its die-cast aluminum baseplate ensures maximum durability and a
cooler, more efficient operation.

© 2015 Sensata Technologies
Introduction
3
The MMSA1012 inverter/charger is equipped with the following:
• Continuous 1000-watt output power and 50-amp charging (at
45°C, or 113°F)
• Numerous protection features to provide peace-of-mind
operation and safe operation
• AC transfer switch circuitry; allowing incoming AC power to
continue to pass thru to power loads even if the inverter is off
• Dead battery charging for batteries that are extremely low
• Automatic 4-stage battery charger with power factor correction
and temperature compensation—for optimum battery charging
(using the temperature sensor)
• DC terminals with Anderson connectors for quick DC connection
• True RMS output voltage regulation to ensure the inverter
will deliver the correct amount of power—within the DC input
voltage range and the continuous output power level
• Quick connection accessory and remote ports—easily accepts
several optional remote controls and the Battery Temp Sensor
1.5.1 External MMSA1012 Features
This section covers the many features available on the MMSA1012
inverter.
1Power ON/OFF Switch & LED Status Indicators –
a momentary pushbutton switch that alternately turns
the inverter on or off, and five LED status indicators
(INV, BULK, ABSORB, FLOAT, and FAULT) for monitoring
inverter and charger operation.
2Auxiliary Output Circuit Breaker (AUX OUT) – a 20-
amp circuit breaker that provides overload protection for
the aux DC output.
3Input Circuit Breaker (AC IN) – a 20-amp circuit breaker
to protect the unit’s internal wiring and pass-thru relay.
4Output Circuit Breaker (AC OUT) – a 15-amp circuit
breaker to provide another layer of overload protection.
This is not a branch circuit-rated breaker. Separate output
breakers may be required on the output.
5GFCI Outlet – a Ground Fault Circuit Interrupter outlet
(with test and reset capability).
6Mounting Flanges (x4) – two flanges on each side to
secure the inverter to a shelf/wall.

© 2015 Sensata Technologies
Introduction
4
8
7
Figure 1-3, Left Side Features
2
3
4
5
6
1
Figure 1-2, Top Side Features
7AC Input Connection – a strain relief clamp with a 3 ft.
standard plug-in power cord to provide AC power to the
inverter.
8DC Ground Terminal – a ground connection used to tie
the exposed chassis of the inverter to earth ground, or to
the vehicle’s DC grounding system. Terminal accepts CU/AL
conductors from #14 to #6 AWG (2.1 mm2to 13.3 mm2).

© 2015 Sensata Technologies
Introduction
5
Figure 1-4, Right Side Features
911 12
10
9Battery Temperature Sensor Connection –a RJ11 port
that accepts the supplied remote Battery Temp Sensor
(BTS) cable.
10 Remote Connections – two RJ11 ports that allow two
remote controls to be connected for adjusting/monitoring
inverter and charger operation.
11 Dual In-line Package (DIP) Switch – 10 individual slide
switches that are used to determine the MMSA inverter/
charger’s operating parameters.
12 3-Port Terminal Block – three spring-loaded clip
terminals to connect an optional 20-amp DC auxillary
device, a ignition control switch, and a ground remote
control switch.
13 Exhaust Vent – ventilation openings that allow heated air
to be removed by the internal cooling fan.
14 Model/Serial Number Label – includes model/serial
number and provides specifications and information on the
inverter and charger.
Figure 1-5, Back Side Features
13
14

© 2015 Sensata Technologies
Introduction
6
15 Warning and Information Label –provides pertinent
information for safely using the inverter.
16 Positive DC Terminal – the inverter’s connection to the
positive terminal on the battery bank. The MMSA1012
comes with one end of a red #2 AWG DC cable already
connected to the inverter’s positive terminal (Figure 1-6),
and the other end with an Anderson connector (SB175)
attached (Figure 1-7).
17 Negative DC Terminal – the inverter’s connection to the
negative terminal on the battery bank. The MMSA1012
comes with one end of a black #2 AWG DC cable already
connected to the inverter’s negative terminal (Figure 1-6),
and the other end with an Anderson connector (SB175)
attached (Figure 1-7).
18 Intake Vent – ventilation openings to pull in air to help
keep the inverter cool for peak performance.
Figure 1-6, Front Side Features
Figure 1-7, MMSA1012 Inverter’s Anderson Connector
15
18
16
17
Anderson
connector
(SB175)

© 2015 Sensata Technologies
Introduction
7
Figure 1-8, Battery Temperature Sensor
1.5.2 Battery Temperature Sensor
A plug-in external Battery Temperature Sensor (BTS) is provided
(Figure 1-8). When installed, the BTS automatically adjusts the
battery charger’s BULK, ABSORB, and FLOAT voltage set-points
based on temperature for better charging performance and longer
battery life. If the temperature sensor is not installed and the
batteries are subjected to large temperature changes, the battery
life may be shortened.
The BTS cable comes with a RJ11 connector that plugs into the BTS
port on the side of the inverter (Figure 1-4, Item 9). Refer to Figure
2-4 for installation instructions, and to Section 4.4 for information
on the operation of the BTS.
~½”
(~1.3 cm)
~¾”
(~2 cm)
~1”
(2.6 cm)
0.375”
(~1 cm)
~2”
(5.1 cm)
Side View
Cable
Front View

© 2015 Sensata Technologies
Installation
8
2.0 Installation
2.1 Pre-Installation
Before installing the inverter, read the entire Installation section.
The more thorough you plan in the beginning, the better your
inverter needs will be met.
WARNING: Installations should be performed by qualified
personnel, such as a licensed or certified electrician. It
is the installer’s responsibility to determine which safety
codes apply and to ensure that all applicable installation
requirements are followed. Applicable installation codes
vary depending on the specific location and application of
the installation.
Info: Review the safety information on pages ii-iii before
proceeding with your installation.
The basic system diagram shown in Figure 2-1 should be reviewed
to assist you in planning and designing your installation.
2.1.1 Unpacking and Inspection
Carefully remove the MMSA1012 inverter from its shipping container
and inspect all contents. Verify the following items are included:
• MMSA1012 inverter/charger
• Connected positive and negative battery cables with Anderson
connector attached
• Battery Temperature Sensor
• MMSA1012 Owner’s Manual
• Warning label
If items appear to be missing or damaged, contact your authorized
dealer or Sensata.
If at all possible, keep your shipping box. It will help protect your
inverter from damage if it ever needs to be returned for service.
Save your proof-of-purchase as a record of your ownership; it will
also be needed if the unit should require in-warranty service.
Record the unit’s model and serial number in the front of this manual
in case you need to provide this information in the future. It is much
easier to record this information now, instead of trying to gather it
after the unit has been installed.

© 2015 Sensata Technologies
Installation
9
Figure 2-1, MMSA1012 Model Basic Installation Diagram
Overcurrent
Device
AC Loads
AC
OUT
AC IN
Battery
Bank
Medical devices
DC
Disconnect
DC
Ground
Anderson
Connectors
Monitor

© 2015 Sensata Technologies
Installation
10
2.2 Locating and Mounting the Inverter
WARNINGS:
• Do not mount the inverter near any flammable or
combustible fluid or components.
• Provide adequate clearance/ventilation to the inverter.
• Mount only on a “non-combustible” surface.
• Maximum ambient temperature around the inverter
must not exceed 113°F (45°C) to meet power
specifications.
The inverter should only be installed in a location that meets the
following requirements:
Clean and Dry – The inverter should not be installed in an area
that allows dust, fumes, insects, or rodents to enter or block the
inverter’s ventilation openings. This area also must be free from any
risk of condensation, water, or any other liquid that can enter or fall
on the inverter. The inverter uses stainless steel fasteners, plated
copper busbars, and a power-coated aluminum base. Also, the
internal circuit boards are conformal coated. The above measures
are undertaken to help fight the harmful effects of corrosive
environments. However, the life of the inverter is uncertain if used
in any of these types of environments, and inverter failure under
these conditions is not covered under warranty.
Cool – The inverter is rated for indoor use only and should be
protected from direct exposure to the sun or to any equipment that
produces extreme heat. The ambient air temperature should be
between -4°F and 140°F (-20°C to 60°C); realize that the inverter’s
continuous output power and continuous charger current are rated
at 113°F (45°C), so the cooler the better within this range.
Ventilated – In order for the inverter to provide full output power
and avoid over-temperature fault conditions, do not cover or block
the inverter’s ventilation openings and ensure there is enough
space to allow heated air inside the inverter to escape. Provide as
much clearance around the inverter’s intake and exhaust ventilation
openings as possible (Figure 1-5, Item 13 and Figure 1-6, Item 18).
If installed in an enclosure, a fresh air intake opening is recommended
to allow cool air from the outside to flow into the inverter and heated
air to exit away from the inverter and the enclosure.
Safe – Keep flammable/combustible materials (e.g., paper, cloth,
plastic, etc.) that may be ignited by heat, sparks, or flames at a
minimum distance of 2 feet (60 cm) away from the inverter. Do not
install this inverter in an area that contains extremely flammable
liquids like gasoline or propane, or in locations that require ignition-
protected devices.

© 2015 Sensata Technologies
Installation
11
Close to the battery bank – As with any inverter, it should be
located as close to the batteries as possible. Long DC wires tend to
lose efficiency and reduce the overall performance of an inverter.
However, the unit should not be installed in the same compartment
as the batteries or mounted where it will be exposed to gases
produced by the batteries. These gases are corrosive and will
damage the inverter; also, if these gases are not ventilated and
allowed to collect, they could ignite and cause an explosion.
Accessible –Do not block access to the inverter’s remote control
and accessory ports. Also, allow enough room to access the DC
wiring connections as they will need to be checked and tightened
periodically. See Figure 2-3 for the MMSA’s dimensions.
Mounting Orientation – To meet regulatory requirements, the
MMSA1012 inverter/charger can only be mounted on a horizontal
surface (right-side up or up-side down on a shelf/table) or vertical
surface (right-side up on a wall/bulkhead), as shown in Figure 2-2.
The inverter must be mounted on a “non-combustible” surface,
and this surface and the mounting hardware must be capable of
supporting at least twice the weight of the inverter. After determining
your mounting position, use the base of the inverter’s chassis as
a template to mark your mounting screw locations. Remove the
inverter and drill pilot holes into the mounting surface.
As this unit is used in a mobile application, you may want to place
flexible washers or bushings between the mounting surface and the
inverter’s mounting flanges to reduce vibration.
Once the inverter has been properly mounted, you can begin to wire
the DC connections.
Figure 2-2, Approved Mounting Orientations
Shelf Mounted
(right-side up)
Shelf Mounted
(up-side down)
Wall Mounted
(right-side up)

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Installation
12
Mounting holes x4
[¼” (.64 cm) diameter]
10.0"
(25.4 cm)
16¾"
(42.5 cm)
6¾" (17.1 cm)
8½" (21.6 cm)
7½" (19.1 cm)
6¾" (17.1 cm)
RESE T
RESE T
TE ST
TE ST
AUX O UT
AC IN
AC OU T
Figure 2-3, MMSA1012 Inverter Dimensions
2.3 DC Wiring
This section describes the inverter’s required DC wire sizes, the
recommended disconnect/overcurrent protection, and how to make
the DC connections to the inverter and the battery bank.
WARNING: Even though DC voltage can be regarded as “low
voltage”, significant hazards may be present, particularly
from short circuits of the battery system.
CAUTION: The inverter is NOT reverse polarity protected—
which means if the negative and positive battery voltage is
connected to the inverter backwards, the inverter will likely
be damaged. Use a voltmeter to verify the correct polarity
BEFORE connecting the DC wires.
CAUTION: DO NOT connect the battery cables to the
inverter until all wiring is complete and the correct DC
voltage and polarity have been verified.

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Installation
13
Refer to Figure 2-4 when connecting the DC wires to the battery.
Also, consider the following requirements to ensure maximum
performance:
• The DC positive and negative cables connected to the inverter
from the battery bank should be tied together with wire ties/
straps or electrical tape approximately every 6 inches (15.3
cm). This helps improve the surge capability and reduces the
effects of inductance, which improves the inverter waveform
and reduces the wear of the inverter’s filter capacitors. Keeping
the battery cables close together also reduces the chance of
radio frequency interference.
• Make sure cables have a smooth bend radius and do not become
kinked. Follow existing wire runs where possible.
• The battery bank voltage MUST be between 9.0-17.0 volts for
the inverter to operate. If the voltage exceeds 17.0V, the inverter
may be damaged.
• To ensure the maximum performance from the inverter, all
connections from the battery bank to the inverter should be
minimized. The exceptions are the DC fuse and disconnect, or
the DC circuit breaker—required at the battery to protect the
DC wiring—in the positive line. Any other additional connection
will contribute to additional voltage drops, and these extra
connection points may loosen during use.
• A brief spark or arc may occur when connecting the battery
cables to the inverter DC terminals; this is normal and due to
the inverter’s internal capacitors being charged.
• Before routing the wiring, color code the DC cables/wires to the
battery bank with colored tape or heat shrink tubing: RED for
positive (+); WHITE for negative (–); and GREEN (or bare copper)
for DC ground, to avoid polarity problems.
• A cable should be connected directly from the inverter negative
terminal to the battery negative connection; this ensures the
inverter has a reliable return path directly to the battery. Do not
use the chassis in place of the battery negative connection to
the inverter.
2.3.1 DC Wire Sizing
It is important to use the correct sized DC wire to achieve maximum
efficiency from the system and to reduce fire hazards associated
with overheating. Always keep your wire runs as short as practical
to prevent low voltage shutdowns and to keep the DC breaker from
nuisance tripping (or open fuses) because of increased current draw.
See Table 2-1 to select the minimum DC wire size (and corresponding
overcurrent device) required based on your inverter model. The cable
sizes listed in this table are required in order to reduce stress on
the inverter, minimize voltage drops, increase system efficiency, and
ensure the inverter’s ability to surge heavy loads.

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Installation
14
Table 2-1, Recommended DC Wire/Overcurrent Device
Inverter Model
MMSA1012
Maximum Continuous
Current1133 amps
DC Grounding Electrode
Wire Size2#6 AWG
(13.3 mm2)
Minimum DC Wire Size3
(75°C rating in free air)
#2 AWG
(33.6 mm2)
170 amps
Maximum DC Fuse Size4150 amps with
time delay
Increased
size for
longer
distance
5 to 10 feet = #2 AWG
(33.6 mm2)
10 to 15 feet = #1 AWG
(42.4 mm2)
Note1– Maximum Continuous Current is based on the inverter’s continuous
power rating at the lowest input voltage with an inefficiency factor.
Note2– Per the NEC, the DC grounding electrode conductor can be a
#6 AWG (13.3 mm2)conductor if that is the only connection to the grounding
electrode and that grounding electrode is a pipe, rod, or plate electrode.
Note3– Wire size is based on the requirements needed to increase efficiency
and reduce stress to the inverter.
Note4– The next larger standard size overcurrent device may be used if
the de-rated cable ampacity falls between the standard overcurrent devices
found in the NEC.
If the distance from the inverter to the battery is >5 feet (1.5 m),
the DC wire will need to be increased. Longer cable distances affect
the performance of the inverter. See the lower part of Table 2-1 to
determine the minimum DC wire size needed for various distances
greater than 5 feet—based on your inverter model.
DC Wire Size Exception: In an OEM RV application, smaller DC
wire (with appropriate overcurrent protection) may be used if the
inverter will only be connected to a dedicated load, and the inverter
and dedicated load have been thoroughly tested and sold together
by the OEM as a complete system.
2.3.2 DC Overcurrent Protection
For safety reasons and to comply with electrical code regulations, DC
overcurrent protection must be provided as part of the installation.
The DC overcurrent protection device must be installed in the
positive DC cable line, it can be a fuse (with disconnect switch) or
a circuit breaker and must be DC-rated. It must be correctly sized