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L-2523 Rev. 20130412
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DOMETIC BATTERY-BASED ENGINE-OFF AIR
the basics
CONDITIONING FOR SLEEPERS AND DAY CABS
■ CARB exempt
■ EPA and SmartWay certied
■ No federal excise tax
■ Complies with all federal, state and local idling regulations
■ Eligible for grant and loan programs
■ Fully integrated turnkey package includes all components needed for
complete installation
■ 7,000 or 10,000 BTU 115V air conditioning system
■ 2,000 Watt Modied Sine Wave (MSW) inverter with optional built-in charger
■ Absorbed glass mat (AGM) batteries
■ High-capacity alternator to recharge batteries quickly
■ Optional shorepower connection
■ Built-in low-voltage cutoff circuit to ensure sufficient battery power to restart
engine
■ Thoroughly eld tested for the toughest over-the-road conditions
■ Backed by nationwide service and support network
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DOMETIC AIR CONDITIONING SOLUTIONS FOR TRUCKS
Dometic builds the industry’s most rugged and reliable battery-based engine-off
air conditioning solutions for trucks. Our systems are designed, engineered and
tested to give you years of trouble-free performance under the toughest over-theroad conditions. They are based on more than 50 years of experience in designing,
engineering, building and supporting HVAC systems for harsh environments, and
they’re backed by extensive technical assistance and nationwide service.
Our green systems are the best answer to today’s environmental challenges. There
is no diesel generator, no fuel consumed, no exhaust fumes to pollute the air, no oil
to change, no noise, no vibration, no belts to tighten, and no worries about lawenforcement violations and nes. They are 100% CARB compliant, and they meet
all federal, state and local clean-air laws. In addition, you don’t need to worry about
warranty issues with the truck’s manufacturer, since our battery-based solutions do
not break into the truck’s fuel or cooling systems.
Our 7,000 and 10,000 BTU/hr sleeper systems provide ample cooling to keep
you comfortable while meeting the federal hours of service (HOS) requirements,
operating for 10-14 hours without recharging the batteries under normal duty-cycle
conditions. The high-capacity alternator recharges the batteries in 5.5–6 hours while
driving down the road.
Our 7,000 BTU/hr day-cab systems are designed to meet the usage patterns for dayroute and terminal-to-terminal operations.
In this booklet, we’ll explain how to select and specify the system that meets your
needs, and provide a few tips on how to get the best results when operating the
system. If you have any questions, please give us a call at +1-804-746-1313 or email
us at sales@dometictruck.com.
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the basics
batteries are recharged by a high-capacity alternator. When 115V AC shorepower is available, it can also be
used to drive the air conditioner.
When looking at battery-based air conditioning, you should think of it as an engineered, integrated
system comprised of several components which have been carefully chosen and tested to ensure reliable
performance.
A belt-driven compressor on the truck’s engine supplies air conditioning
when you are driving or idling. When you shut down the engine,
however, you need a separate air conditioning system that runs on an
alternative source of power.
Dometic has developed an engine-off comfort-control solution that pulls
12V DC power from a bank of heavy-duty batteries and inverts it to
115V AC power, which drives the electric powered air conditioner. The
Air Conditioning Units
There are two basic choices: split systems and self-contained “package” units. In most cases, the split system
is preferred, since it uses less interior space and offers more installation exibility. We will focus on the split
system. However, if you are interested in a “package” unit solution,
please contact our sales office at +1-804-746-1313 or visit our website
at www.dometic.com/truck.
Outside condensing unit mounted on back of cab
Inside evaporator unit seen from the side
compartment
Dometic’s patented split-system design consists of an outside
condensing unit and an inside evaporator/compressor unit. The
outside unit can be mounted horizontally or vertically on the back of
the cab, but may also be mounted horizontally on the undercarriage.
The inside unit is usually mounted under the bunk or in a side storage
locker for a sleeper, or between the seats in a day cab. The two units
are connected by reusable precharged refrigerant linesets with quickconnect ttings. The system is designed so that both units automatically
charge to the correct refrigerant pressure as soon as the linesets are
connected. No special tools are required.
The air conditioning system also includes ducts, grills, condensate
drain and electrical wiring, as well as a digital display/control panel.
The air conditioning systems can be ordered for cooling only with builtin electric heat elements.
Note that the Dometic system is not a “bunk cooler” that blows cool air
on the driver, but a true compressor-driven air conditioning system that
provides ample cooling capacity for the entire space.
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optional
Batteries
Dometic systems use absorbed glass mat (AGM) batteries, which
can be deeply discharged and rapidly recharged without damaging
the batteries. They are capable of up to 500 discharge-recharge
cycles. The number of batteries will depend on the capacity of the
air conditioner, size of the space to be cooled and user prole of the
truck. Dometic offers a range of choices in external battery boxes that
can be mounted on one of the side rails or between the rails behind
the cab. Replacement AGM batteries are readily available through
battery distributors across North America.
Inverter
Dometic species a 2,000 Watt inverter with a Modied Sine Wave
(MSW) output designed for extended periods of operation. This
high-performance inverter is designed to handle the extra load
requirements of the air conditioner as well as house loads. It also
protects the unit from electric spikes that can occur when the
compressor cycles on and off. The inverter can also be ordered with
an optional built-in charger. Most importantly, the inverter has a lowvoltage cutout that automatically turns off 115V AC power whenever
the batteries drop below a preset voltage. This ensures you will
always have sufficient battery power to restart the truck. The inverter
is approximately the same size as a Group 31 battery and is normally
mounted inside the battery box.
accessories
Group 31 AGM deep-cycle batteries replace house
batteries
Alternator
Dometic’s system uses a high-capacity 270 or 300+ amp alternator
to recharge the batteries when the engine is running. This alternator
replaces the standard alternator on the engine. High capacity is
required in order to recharge the batteries in a reasonable period of
time, 5.5–6 hours. In day-cab applications, recharge must take place
within typical point-to-point runs.
Shorepower
The Dometic system may be ordered with an optional shorepower
connection, allowing you to run the air conditioner on an external
115V power source when available. If the optional combination
inverter/charger unit is installed, you can also recharge the batteries
when plugged into shorepower. TMC recommends a minimum of one
20 amp circuit for shorepower connections. You should use a heavyduty cord with a minimum of 12-gauge wire (50 ft.). Remember there
will be a voltage drop across the cord, so use the minimum length
necessary to reach your outside power source.
High-capacity alternator replaces standard alternator
Shorepower plug
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SPECIFYING
A SYSTEM FOR
Dometic’s engine-off air conditioning systems for sleepers are designed
to keep the entire sleeper cooled for a minimum of 10 hours to meet the
HOS requirements.
SLEEPERS
System capacity depends on a number of factors, such as the size and
shape of the space to be cooled, the amount of insulation, the size and
location of windows, the color of the truck and the ambient temperature
outside. Dometic offers 7,000 and 10,000 BTU/hr systems.
The number of batteries needed will depend on the capacity of the air conditioner and the length of time you
will need to run the air conditioner between recharges. The table below offers general guidelines. Note that the
air conditioner normally will not run continuously, but will cycle on and off as needed to maintain the selected
setpoint. The 60% duty cycle in the table means that the air conditioner runs 60% of the time, and is off 40%
of the time. Typically, sleeper systems are specied with 7 to 8 batteries. Day-cab systems will operate to spec
with 3 batteries.
If you are specifying optional built-in electric heat, use the following table to size the electric heat modules.
Electric heat uses a tremendous amount of power. Each KW of heat requires about 8.2 amps of alternating
current. When using electric heat, Dometic systems will only get approximately 50-60% of the run time
compared to the cooling cycle.
Dometic offers a selection of prewired battery boxes that will save time and money on installation. The box can
be mounted on either side rail, or between the rails behind the sleeper. To calculate your return on investment
for a Dometic engine-off sleeper air conditioning system, refer to the following table:
72" High Rise
Replace existing 4 lead-acid batteries with AGM batteries and
Batteries 8 Group 31 AGM
Alternator 320 amp high output Replace existing alternator on truck engine.
Inverter
HVAC System 10,000 BTU/hr
Batteries 7– 8 Group 31 AGM
Alternator 320 amp high output Replace existing alternator on truck engine.
Inverter
HVAC System 7,000 BTU/hr
2,000 Watt Modied Sine
Wave (MSW)
2,000 Watt Modied Sine
Wave (MSW)
add 4 more AGM batteries. Check on Dometic’s selection of
prewired battery boxes to save time and money on installation.
Specify optional inverter/charger combination for charging
batteries from shorepower.
It includes ducts, grills, electric wiring and digital control/
display panel.
48"– 60" Sleeper
Replace existing 4 lead-acid batteries with AGM batteries
and add 3–4 more AGM batteries. Check on Dometic’s
selection of prewired battery boxes to save time and
money on installation.
Specify optional inverter/charger combination for charging
batteries from shorepower.
It includes ducts, grills, electric wiring and digital control/
display panel.
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Aerial view of the inside system including ducts and grills
Prole Heat Capacity
48"– 60" Sleeper 1.0 KW
72" High Rise 1.5 KW
Between the rails battery box, showing an inverter
in the upper right corner
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SPECIFYING
A SYSTEM FOR
Day-cab trucks are also subject to clean-air regulations that restrict
idling time, and there is an increasing demand for engine-off air
DAY CABS
times are shorter. It also uses a slightly smaller alternator than the sleeper system.
The number of batteries needed will depend on the length of time you will need to run the air conditioner
between recharges. Note that the air conditioner normally will not run continuously, but will cycle on and off as
needed to maintain the selected setpoint. The 60% duty cycle in the table means that the air conditioner runs
60% of the time, and is off 40% of the time.
The outside condenser mounts horizontally or vertically on the back of the cab. The inside unit, containing the
compressor, evaporator and blower, is packaged in a molded composite cover and mounts between the seats
in the cab. The cover contains multiple air outlets which can be pointed to discharge in different directions. The
display/control and inverter control are mounted directly on the driver’s side of the unit for easy accessibility.
conditioning solutions for these trucks as well as sleepers.
Dometic’s day-cab systems are designed to meet the space constraints
and capacity requirements of day cabs to meet typical usage patterns.
The day-cab system requires fewer batteries than a sleeper, since run
Day-cab unit between the seats
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The following table provides simplied guidelines to meet these user proles:
Day route – Cools the cab during a typical 15-30 minute wait and recharges in 20-30 minutes
Terminal – Cools the cab for up to 2 hours, recharges in 1 hour of run time
Day Route
Batteries 3 Group 31 AGM Replace existing lead-acid batteries with AGM batteries.
Alternator 270 amp high output Replace existing alternator on truck engine.
Inverter
HVAC System 7,000 BTU/hr
2,000 Watt Modied Sine
Wave (MSW)
All inside components are packaged in a molded plastic
shell.
Terminal Operation
Batteries 3 Group 31 AGM Replace existing lead-acid batteries with AGM batteries.
Alternator 270 amp high output Replace existing alternator on truck engine.
Inverter
HVAC System 7,000 BTU/hr
2,000 Watt Modied Sine
Wave (MSW)
All inside components are packaged in a molded plastic
shell.
Hours Running on Battery Power (Approximate)
7,000 BTU/hr
Number of Batteries 100% Run 60% Run
2 1.5 hours 2.25 hours
3 2.0 hours 3.0 hours
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OPERATION AND
Insulation
MAINTENANCE
If you are ordering a new truck, we strongly recommend requesting the upgraded insulation package. There
are also measures you can take to reduce the heat load in your truck. Insulate the oors with foam under
the carpet. Get heavy-duty blackout curtains between the cab and sleeper. Cover the skylights and windows
with reective shades when stopped. Park in the shade whenever possible, and switch off heat-producing
appliances.
Most truck cabs and sleepers are insulated with a value of
approximately R1 to R1.25. Even the cold-weather packages
offered with some new trucks have an insulation value of only
R2. By comparison, most new homes are insulated to R30. TMC
recommended practices call for R4.2 as a standard insulation package
and greater than R4.6 in a premium package. This standard, once
adopted by the industry, will go a long way toward improving the cooling
efficiency of your engine-off air conditioner.
Replacing batteries
Major-brand replacement AGM batteries are available from distributors throughout North America. Do not mix
battery types. Example: One would not have 4 typical wet-cell, lead-acid batteries and 4 agm batteries. Overall
charging will not occur and battery life will be reduced.
Maintenance
Voltage Drop: The voltage drop is measured between the charging point (alternator or battery charger) and the
battery that is the farthest from the charging point and should be no more than 0.2V DC. (Any more will result
in improper charging and run time will be shortened.)
Inspect the batteries frequently. Check for tight electrical connections and also check for corrosion at battery
terminals.
Inspect and clean the air lter regularly to ensure good airow across the evaporator coil. You will nd the air
lter in the return-air path, either directly behind the grill or in front of the evaporator coil on the unit.
Do not block the airow path between the return-air grill and evaporator coil with pillows, blankets, papers or
other objects.
Check the condensate drain to make sure water is draining properly. If the drain is clogged, clean it.
Periodically inspect for chafe on outside wires, cables and refrigerant lines.
Inspect and clean debris from the condenser unit mounted outside the truck.
Note that you should never need to recharge the refrigerant loop under normal operating conditions. If the
refrigerant level needs to be adjusted, federal law requires that it must be done by an EPA-licensed HVAC
technician with proper tools to avoid accidental discharge of refrigerant gas into the air.
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Dometic LLC
2000 N. Andrews Ave.
Pompano Beach, FL 33069
+1 804.746.1313
www.dometic.com/truck
Email: truckinfo@dometic.com
Patents: 7,171,822
7,234,315 B2
7,140,192
7,316,119
7,237,397 B2
ISO 9001:2008 L-2523 Rev. 20130412
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