Cutting down on idle time has been a goal of fleet mangers for some time. But when diesel fuel prices hit $4-plus per gallon, achieving that goal becomes a matter of some urgency. Add to that a number of anti-idling regulations in several states and municipalities, and finding a way to get drivers to turn the truck off when stopped is a key business objective. California, for instance, prohibits commercial trucks of more than 10,000 pounds GVW from idling for more than five minutes within the state's borders. Fines for violating this rule start at $300 and can be as much as $1,000 per day.

It seems simple on the face of it. Reducing idle time saves fuel, saves on preventive maintenance and can prevent hefty fines. But cutting idle time is tougher than one would think, because drivers have to go along with the program. And drivers are unlikely to do so unless there is some alternative way they can stay warm in the winter and cool in the summer while they are stopped in their trucks.

Auxiliary power units and other non-idle technologies promise a solution. Adoption of these technologies has been slow among fleet operators, but that could change. Interest in these technologies has grown in the past year.

"Demand has been good," says Eduardo Andrade, business manager-special products for Carrier Transicold. Most of the increase in demand has been from fleets. But high fuel prices are not entirely the reason. "This is something that did not start with fuel prices. This is something that started as a gradual process we started seeing in 2006 or so.

"The increase in demand has to do with the maturity of the industry as well," he says. "There are more credible players coming in. You have more reliable products, more reliable parts distribution and more capability. This allows the larger operators to rely on these products."

Of course, Andrade points out that owner-operators have been buying APUs "for over a decade and they continue to be interested."

Shawn Wasson, auxiliary power unit business leader for Cummins, agrees that demand is up. "We've seen business pick up this year," he says, noting that the market was down last year, primarily due to fleets pre-buying trucks in 2006. "This quarter has seen sales moving upward."

Wasson says APU demand follows new truck purchases, because most truck owners want to have as long a payback time as possible. Last year, truck sales were down and so were APU sales. While there are no hard figures available, he says, the overall market for APUs peaked in 2006 at about 30,000 units. It dropped to between 15,000 and 20,000 in 2007 and may end up somewhere between 20,000 and 25,000 in 2008. "We think there may be some pent-up demand for these technologies," he says. "Many fleets are waiting to see what happens with APU emissions regulations in California and the possible adoption of those rules by other states before deciding which way to go."

Wasson says high fuel prices have changed the equation for fleets. "Three or four years ago, the question for fleet operators was 'Should I do something about idling?' Now the question is 'What should I do about idling?'"

If a fleet's idle time is high, an APU will probably be the best choice. On the other hand, if a fleet does not have a lot of idle time, some other option, such as an electric HVAC system or engine shut down devices, may be preferable.

With installed prices for APUs running from around $7,500 to $9,000, depending upon the number of units purchased, a fleet's potential payback depends on how much idle time they have and how much fuel they are using. A fleet with under 20 percent idle time and a short trade cycle may not be the best candidate for APUs, Wasson says. Fleets and other potential customers can find payback calculators on most APU manufacturers' web sites. "As long as you understand what to plug in, most of these calculators are pretty good," Wasson says, and will help a fleet get a pretty good idea if an APU is the right solution for them.

In addition to the fuel savings and regulatory issues, driver retention is also a key factor for fleets looking to purchase an APU. Many fleets see these technologies as ways they can keep their current drivers happy and to recruit new ones.

The interest in APUs is reflected in the growing number of companies selling these and similar products. In recent years, a number of companies from large to small have entered the market.

In an interview last year, Amy Egerter, marketing manager for Rigmaster Power Corp., Toronto, said her company was seeing much more interest from fleet buyers. "The owner-operators were first," she said, "but with higher fuel prices, regulatory issues and a push by the U.S. Environmental Protection Agency to decrease truck idling, more fleets are spec'ing APUs." Programs such as the EPA's SmartWay Transportation Partnership provide grants to states and air districts to promote anti-idling programs and technologies. These programs can include low-interest financing and in some cases, funding for buying technologies such as APUs, inverter/chargers, electric air conditioners and heaters. "Fleets have been coming on board en mass," Egerter says. "These programs are doing a lot to bring fleets in."


Auxiliary power units come in a variety of configurations, with units featuring small diesel engines generally falling into one of two types - stand-alone or integrated systems. Stand-alone systems essentially provide backups for the truck's components and typically include a small engine, an alternator/generator to produce electrical power, an air conditioning condenser and compressor, heater core and power outlets.

Stand-alone systems typically feature three or four components: The main unit, including the engine, radiator, alternator/generator, AC compressor and often the AC condenser, is mounted on the truck's side rails. A heater/air conditioner unit is usually mounted under the sleeper bunk. A control panel is mounted in the cab or sleeper allowing the driver to control the unit without exiting the truck.

Integrated systems tie into much of the truck's existing systems. The Willis APU from Auxiliary Power Dynamics is one such product. "We use everything on the truck except the air conditioner compressor," Watson says. "Like a lot of makers, we use the truck's coolant and recirculate the coolant throughout the truck to provide heat to the engine and heat to the truck," he says. "We go through the truck's condenser; we use the truck's expansion valve." The system makes use of the trucks HVAC system so that it "blows through all the truck's vents." This design does not take up space underneath the sleeper bunk. Other features of the WIllis product include a 150-amp alternator, solid-state electronic control, a 3-cylinder 18.8-horsepower Kubota engine, and an optional 1,750 watts of continuous household power using a Xantrex inverter and fully wired power outlets. Information is available on the Web at

Carrier's ComfortPro is a hybrid system. It can work off of shore power, or use its diesel-fueled Kubota engine to generate power. One of the key design differences in the Carrier system is the "hybrid diesel electric-approach," Andrade said. "Instead of a belt-driven or open drive automotive style compressor, we have the APU engine driving a 4-kw AC generator which in turn drives a sealed compressor, similar to what you have in your refrigerator." This unit is mounted inside the sleeper with an AC motor-driven blower. The split design "allows us to remove certain components from the harsh environment of the frame rail and place them inside the comfortable ride and protected environment of the sleeper." In this system, the alternator is dedicated to charging the truck's batteries. Information is available at

Blackrock Systems, Reno, Nev., offers the Blackrock APUs with either a 2-cylinder or 3-cylinder Yanmar diesel engine. The 3-cylinder engine is designed for large sleepers to provide more A/C and electrical output. The engine provides the power to run the A/C compressor, 120-volt generator and a 12-volt DC alternator. The Blackrock features heating, cooling, AC power, and a 3-year/4,000-hour limited warranty on the engine and a 2-year/4,000-hour limited warranty on the APU. For more information, go to

Kohler Power Products, Kohler, Wis., began production of its APU in April. The 5-kilowatt unit features a compact design and weights just under 350 pounds. It's a self-contained unit featuring an air-cooled engine. The unit delivers 120-volt AC power and 50-amp DC power. It is also designed with a direct-drive alternator, eliminating alternator belts. The unit mounts on the truck's side rail and comes with Kohler's Advanced Digital Controller as standard equipment. The unit features battery charging, heating and cooling. For more information, go to

The Cummins ComfortGuard APU System represents the engine maker's first complete auxiliary power unit system for over-the-road trucks. Wasson says the company has received certification from the California Air Resources Board for its units on a truck with a Cummins ISX engine. In this configuration, the exhaust from the APU is re-routed through the engine's exhaust control system. For trucks with other engines, the Cummins product will use a small diesel particulate filter on the APU's engine. Cummins is awaiting CARB certification for this solution.

The ComfortGuard combines the company's Onan generator with HVAC components. The system features quick disconnects and pre-charged A/C lines to aid installation. The system can be installed and serviced throughout the U.S. and Canada by Cummins dealers and distributors.

The ComfortGuard's A/C system fits under the sleeper bunk. An electric heater provides heat for cool nights. A home-like thermostat controls the system, which can be set to automatically start based on time of day or the thermostat setting. A 2-cylinder engine provides power for the unit. A Cummins alternator puts out 4,000 watts, 60 Hz AC current to run electrical appliances and 40 amps of 12-volt DC current for battery charging. Information is available at

The Pony Pack 200 from Pony Pack, Albuquerque, N.M., provides electric power, heating and cooling with a 2-cylinder, 10-horsepower Kubota engine, Ford 110-amp alternator, Ford air conditioning compressor, Modine radiator and AC condenser. For information go to

Rigmaster's APUs can be ordered with either a 14-horsepower Caterpillar or Perkins engine. The system features a 6-kilowatt generator and 60-amp alternator that delivers battery charging power and 120 volts AC power. It heats or cools the cab and can power an existing engine-block heater. A cab-mounted control panel allows drivers to set temperature and autostart settings from the comfort of the cab.

Rigmaster says its current models can burn both biodiesel and ultra-low sulfur fuel. For more information,

SCS Frigette's hybrid auxiliary power unit features a 3.5-kilowatt generator, air conditioning compressor and a 7-horsepower Kubota single-cylinder engine.

The system provides heat and air conditioning while charging the truck batteries. It also generates 3,500 watts of 110-volt electricity for on-board appliances. The unit's engine burns about 1/10 gallon per hour. A 60-amp batter charger is included. See more on the Web at

Thermo King's TriPac APU provides engine preheating, battery charging, climate control and electrical power to the cab. It features a microprocessor controller so the driver can easily set truck cab cooling and heating levels.

The truck battery charging system features automatic voltage sensing, and the unit supplies 120-volt electrical power for on-board appliances, computers or other equipment. For information go to


In addition to APUs, fleets also have the option of using electrical-powered HVACs, fuel-fired heaters and other technologies for heating or cooling the cab with the engines turned off.

Bret Reinhardt, president, Sun Power Technologies, Carmel, Ind., noted that, "The largest selling point for our system is there is no fuel consumption. There is no ongoing small engine maintenance. There is no oil to change, belts or hoses to service and the install time for our unit is about one-fifth the time required to install an APU." These systems can either use the truck's existing batteries and alternator or come with their own battery packs and an upgraded alternator. The systems typically use their own vents and blower motors to move heated or cooled air around the sleeper compartment.

The Sun Power Eco-Air 12-volt system is a completely self-contained unit, weighing in at about 430 pounds. It uses its own battery system to run an electric air conditioner. The battery box is installed on the truck's frame rails; a compressor/condenser unit is mounted outside the rear sleeper wall. The evaporator coil hangs inside the truck. The system's batteries are recharged by the truck's alternator when the truck is moving. A charge controller limits the amount of power the unit draws from the alternator and protects against over-charging the system's batteries. Those batteries can serve as backup cranking batteries when needed.

The unit delivers 10,000 Btu of cooling capacity for eight to 12 hours on a single charge. The system's batteries also supply 12-volt DC power to run diesel-fired heaters, such as those from Webasto or Espar, and can supply 12-volt power for "hotel" loads inside the cab. Depending on options, the system costs between $6,100 and $9,000 and can be installed in about four hours. For more information, go to

Dometic Environmental Corp., Pompano Beach, Fla., recently introduced a new family of redesigned auxiliary air conditioning products based on Dometic's patented split-system HVAC technology. These units consist of a redesigned compressor/heater/evaporator/blower unit, which mounts inside the truck, and an external compressor/fan unit, all running on Dometic's new Qt-series digital controls. The inside and outside units are connected by precharged, reusable refrigerant linesets with quick-connect fittings.

The new CHEB and CF units are made with powder-coated aluminum covers to present a more attractive appearance and resist corrosion. The CHEB has been engineered to minimize compressor noise inside the truck. The low-profile CF unit, which can be mounted horizontally under the truck or vertically on the back of the sleeper, has been re-engineered reducing its size and weight.

The split HVAC systems run on 115-volt AC power, which can be supplied by a bank of batteries, an onboard APU or shore power. They are available in 7,000-Btu, 10,000-Btu and 14,000-Btu capacities. Dometic also recently unveiled a battery-powered auxiliary air conditioning system designed specifically for day cabs. More information is available at

Glacier Bay Inc., Union City, Calif., offers the ClimaCab electric system that uses radiant heat transfer to heat the cab while it delivers 8,000 Btu of air conditioning for over 12 hours. For information, go to

Webasto Product North America, Fenton, Mich., sells engine-off heaters and air conditioning units. The company's fuel-fired heaters keep truck cabs and engines warm in the winter. The Air Top 2000 and Air Top 3500 air heater units deliver 7,000 and 12,000 Btu, respectively of heating power and provide between 10 and 20 hours of heating per gallon of fuel. The compact units mount under the bunk in the truck's sleeper compartment.

Webasto also offers the BlueCool cooling system, a bunk cooling system that can provide up to 10 hours of cooling operation while drawing only 3.5 to 6.5 amps from the truck's batteries. The unit uses no fuel, but a cold storage cell that is charged while the truck is being driven. When the truck stops, the truck's engine can be switched off and the BlueCool unit will keep the cab comfortable. The unit uses power from the truck's batteries to move cold coolant between the storage unit and a heat exchanger and to power four air distribution fans. The company says the unit can cool a truck for up to nine hours before needing to be recharged. For more information,

The Bergstrom Nite (No-Idle Thermal Environment) System is an electrical system that cools the sleeper compartment. The system includes a rechargeable battery system, air-conditioning unit and auxiliary heater from Espar Heater Systems. The air conditioning system draws no power from the truck's batteries, but uses a rechargeable deep-cycle battery system that can deliver cooling for up to 10 hours between charges. All the components run on 12-volt DC power, so no power inverter is required. The air-heating system uses about 0.06 of a gallon of diesel fuel per hour.

The unit can be installed on any truck, the company says. For more information, go to

Espar Heater Systems makes fuel-fired heating systems to keep the truck cab warm and to pre-heat the truck engine for improved cold-weather starting and is offered as an option from most truck OEMs. The company recently introduced new on-frame and in-frame products that keep the cab warm and that can also warm the truck's engine. For more, check out

Xantrex Technology's inverter/charger system can provide easy access to shore power. It converts stored battery power into AC power to run appliances such as coffee makers, refrigerators, microwaves, etc. When shore power is available, truckers simply plug in and the system uses shore electricity to power their appliances and recharge the truck's batteries. Xantrex's inverter/chargers wire into the truck's existing electrical system - connecting directly to the battery bank. It converts the batteries DC power into AC power. When plugged into shore power, the unit uses the AC power from the shore connection. For more information, go to