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Zero RPMs

Excessive engine idling consumes more than 800 million gallons of diesel fuel a year.


“No person shall allow any engine to be in operation while the motor vehicle is stationary at a loading zone, parking or service area, route terminal or other off street area.” From this it certainly sounds like Hawaii is serious about limiting engine idling, but so are many other jurisdictions. Leave your engine idling for five minutes in any one hour in some areas of Colorado and you could find yourself in jail for a year.

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Sound kind of crazy to you? Maybe, but economic and environmental demands have changed from times when idling was a reasonable option to where it really no longer makes sense. Government studies indicate that a typical long-haul tractor-trailer idles an average of more than 1,800 hours per year.

This practice contributes to air pollution and noise, moving many states and municipalities to enact laws to reduce idling. Across the industry, excessive idling also consumes more than 800 million gallons of diesel fuel annually, and with the pump price for diesel around $3.00 per gallon, it doesn’t take long for this to add up to serious money.

“It’s in the interest of fleets to be diligent in controlling idle time,” says Zack Ellison, Cummins’ director of customer technical support for North America. “A change in idle time from 40 percent down to 20 percent will effectively improve your fuel economy by 0.3 miles per gallon, and every bit of that money goes right to profit.”

Unnecessary engine wear and the increased maintenance expense that it brings also are factors that should be considered.

Freightliner LLC finds a positive approach often works best. Joseph McCorkel, project engineer – special projects, cab engineering at Freightliner, says, “Saying there’s a ‘problem’ with idling with infers something negative by use of the word. We like to say the rewards for non-idling will continue to increase. The direct costs and fuel savings calculators are long established and continue to increase. Regulatory requirements limiting idling require something be done to allow for a successful rest period. Many fleets have also expressed an environmental awareness about the idling issue and want to be able to show their leadership in this area. Also driver recruiting and retention issues drive the need for more anti-idling systems and more amenities when parked. So costs, regulatory issues, environmental awareness and driver retention all stimulate the growth in anti-idle systems. Financial rewards to the driver for non-idling can produce amazing results compared to what a technology solution alone can achieve.”


The fact remains, however, that some drivers will need to stay comfortable in their cabs during mandatory rest stops. They’ll need to heat cabs and avoid start-up problems in the winter, and cool cabs in the summer. In many cases, they’re also going to be looking for power to operate various electrical appliances. Yet, because of the cost of fuel, Reid Landis, marketing specialist at Webasto Product North America, tells us, “No one can afford to continue to idle. You have to look at something.”

Once you’ve made the decision to improve your bottom line by decreasing engine idling, the next step is to decide what kind of idle reduction technology will likely serve your fleet’s needs.

“A fleet manager needs to weigh the options when  considering using anti-idling technologies,” says John Dennehy, vice president of marketing and communications at Espar Products, which offers a fuel-fired auxiliary heater and self contained air conditioning unit. “There’s a lot of talk about using fuel-fired heaters as opposed to auxiliary power units or even using truck stop electrification. It’s up to the fleet managers to look at where trucks are running and what  drivers need.


“They might not need the full APU. They might not need auxiliary air conditioning. They might just need heat. Managers need to weigh fuel costs, expected return on investment, weight gain etc.”

Anti-idling technologies can be divided broadly into two categories, stationary and mobile.

The dominant player in the former group is IdleAireTechnologies, which offers a self-contained stationary truck stop electrification system comprised of a structure at truck spaces with an HVAC unit for each space attached.

A concentric hose and integral cabling connects the HVAC to a computer-powered service delivery module that fits into adapter in the cab window. The module delivers heat and air conditioning, Internet, local telephone service, satellite television, movies on demand and computer-based interactive driver training to the cab of the truck. It also includes 110V outlets inside and outside the cab for appliances and engine and oil heaters.

Mobile systems
“Limiting idling via the ECU has long been available with engine shutdown timers,” says Freightliner’s McCorkel. “It’s easily done and meets the cost and regulatory issues. I think it could become more complex in the future, such as adding rules dependent on outdoor temperature and time intervals. Although this only really addresses the costs and regulatory issues, I can see where this approach could be workable for some limited applications, such as day cabs in moderate climates.


All electronically controlled truck engines come with idling controls as a built in capability. Detroit Diesel, for example, says, “Prolonged idling wastes fuel, causes unnecessary wear to your engine and throws more pollutants into the air. The DDEC VI optimized idle system makes sure you can maintain engine temperature, battery voltage and cab temperature by automatically starting and stopping your engine.”
Cummins’ Ellison says, “We have the adjustable idle shut down feature in the engine’s control module. We also have the ICON system, which will automatically turn an engine on and off in response to oil temperature and/or cab temperature. It has a ‘soft shutoff’ feature so drivers don’t get jolted awake. ICON generally pays for itself in less than 18 months. It helps to reduce idle time, but it does not eliminate it. We have some fleets that have reduced their idle time as much as 20 percent using the system.”

Optional mobile systems can be broadly divided into two categories, heating or heating/cooling units and auxiliary power units. There is a growing number of suppliers offering a wide range of such products. The most complete listing of these can be found on the Department of Energy’s Energy Efficiency and Renewable Energy Web site A couple of suppliers stand out from the others on this list.


“Fleet trucks commonly idle between 35 and 45 percent of the time,” says Espar’s Dennehy. “Drivers do so, of course, to either heat or cool cabs and sleepers during rest periods. We’re able to supply the same heating and cooling for the driver without idling. Payback is usually less than one year depending on where the trucks are operating.”
Espar air heaters operate for up to 24 hours on a single gallon of gasoline or diesel fuel and are manufactured in 12- or 24-volt models. Outputs ranging from 6,000 BTU to 41,000 BTU can be used for heating bunks, cabins or cargo. The heaters all offer several output levels and cycle between them according to the temperature desired by the user. The company recently partnered with other suppliers and now offers battery-powered air conditioning systems offering 3,500 to 4,000 BTU of cooling using an extra set of two deep cycle batteries that provide up to 10 hours of cooling. These two additional batteries are incorporated into the truck’s electrical system for recharging during normal truck operation.

For more than 30 years, Webasto has been supplying fuel-fired heating units to the American market. Its product line includes both engine pre-heaters as well as fuel-fired air heaters for cabs and sleepers. As a result of customer demand, the company recently introduced a no-idle air conditioning unit called the BlueCool Truck for sleeper cooling. Its Air Top heating systems will effectively heat a truck cab for up to 20 hours on a single gallon of diesel fuel, the company says. This compares with the single hour with a gallon of diesel when idling a truck engine for heat. A pay-back calculator that uses data from your fleet can be found at by clicking on the “Product Calculators” button. Generally, fleets find a payback in less than 18 months, according to Webasto’s Reid Landis. Information on the company’s products can be found at its corporate Web site and a new site for its cab air conditioning line


Maintenance on fuel-fired heaters is quite minimal. “We recommend that drivers start these, even in the summer, once a month to lubricate internal components,” Espar’s Dennehy says. “The only part that needs to be changed is the glow pin igniter. We recommend changing that item annually or semi-annually as needed.”

Thermo King’s TriPac auxiliary heating/cooling temperature management system uses a fuel-fired heater and Thermo King’s Cycle Sentry start/stop technology to achieve fuel efficiency, the company said A two-cylinder diesel engine powers an air-conditioning compressor and a 12-volt alternator, both of which are belt driven. These components power the air-conditioning system, keep the truck batteries charged and provide tractor engine heat, all of which help eliminate idling.

In cool climates, the TriPac engine will only operate if battery charging or engine-block heating is required. If not, only the fuel-fired heater will operate to warm the cab which consuming minimal fuel, Thermo King says.

The system is designed to run fewer engine hours, which saves fuel and extends engine life. An available tractor integration option allows the system to start automatically when the truck engine is turned off, which ensures a charged truck battery and warm engine block when it’s time to restart the engine.


TriPac offers 1,000-hour maintenance intervals designed to match its maintenance intervals with those of the tractor.

Bergstrom’s NITE system combines a lightweight, fully functional air-conditioning system and Espar’s air-heating system – both designed to work independent of the truck’s main engine. In cold weather, the eight-pound heating system keeps the sleeper compartment warm all night using .03 to .06 gallons of diesel per hour, the company says. The 12-volt DC air-conditioning system incorporating a variable speed compressor and brushless technology can keep a sleeper area at 70 to 75 degrees when the outside temperature is 90-plus degrees.

"The NITE system provides long-term, continuous heating and cooling for truck cabs and sleeper compartments without idling the truck engine,” says Howie Heaton, director of sales and marketing for Bergstrom’s Aftermarket Group. “It is absolutely quiet and does not require regular maintenance.” The system can be retrofitted or spec’ed from OEMs on new trucks.

Dometic Environmental Corp. has a 45-year history as a supplier of refrigeration technology for harsh-environment applications. The company has more recently turned its attention to auxiliary air conditioning technology for trucks and is working with OEM engineers to design factory-installed auxiliary air systems for new trucks. The company is partnering with auxiliary power unit companies to develop combined APU/air conditioning packages for existing trucks. See the sidebar for an example of how R.E. West  transportation is using a combined system.


DC Power Solutions recently introduced a self-contained air conditioning unit designed for roof top mounting. Called the DC Top Cool, the two models currently available produce either 6,000 or 12,000 BTU/hour of cooling using either the starting or an auxiliary battery system, the company said.

“The 6,000 BTU unit is typically sufficient to cool a truck’s sleeping compartment,” says Sue Merrell, DC Power’s vice president of sales and marketing. The company will soon be offering a split system that will allow the evaporator to be mounted anywhere inside the cab.

Both Peterbilt and Kenworth have announced the pending introduction of self-contained battery-based systems that provide heating, cooling and electrical power to the sleeper without the need for idling.

Of Peterbilt’s product, called Comfort Class, Landon Sproull, the company’s chief engineer, says, “The system helps ensure operator comfort by maintaining the desired temperature within the sleeper while the truck is not in operation. It provides climate control performance as effectively as traditional systems but uses much less energy to do so. It will provide up to 10 hours of HVAC, ideal for the typical off-duty period of an over-the-road operator.”


Kenworth calls its analogous system the Kenworth Clean Power System and claims its payback to the operator can be measured in months. “Customers with high idling time may receive as much as an 8 percent boost in fuel economy by not idling,” says  Mike Dozier, Kenworth’s chief engineer.
Extensive testing has shown that these systems are able to keep the sleeper cool for 10 hours, even with outside ambient temperatures as high as 95 degrees, according to the OEMs.

Auxiliary power units come with a wide range of optional capabilities and from a growing number of suppliers. Two familiar names are found among the manufacturers offering products in this segment – RigMaster Power, a long established supplier, and Cummins Comfort Guard, a new product.

The former offers a complete stand-alone generator set that runs all night on a couple of gallons of diesel and provides 120 volt "house current", a 60 amp DC alternator to charge a truck’s batteries and an automatic climate control system with in-cab controls. According to the manufacturer, its units, which are powered by a Perkins or Caterpillar diesel, will save enough fuel to pay for themselves in a year. Their internal generators warm the engine block and provide 120 AC voltage for appliances and power tools. Integral DC alternators charge the truck’s batteries and operate marker lights.
The manufacturer recently announced its products will operate on ultra-low sulfur fuels. RigMaster general manager Gary Lisson says, “A RigMaster installed on a current or older truck can easily be removed and installed on a new ULSD truck without any worries. I feel confident knowing that the product that we put out almost two years ago will still be viable in the years to come.”


The new ComfortGuard APU from Cummins is the engine manufacturer’s first complete auxiliary power unit system for over-the-road trucks. “The ComfortGuard APU system is a logical outgrowth of both the engine and idle management products for which Cummins is known, and the RV, marine and mobile generators built under the long-established Onan brand from Cummins,” says Shawn Wasson, APU business leader for Cummins. The A/C system fits beneath the sleeper berth and has a 12,000 Btu capacity. The 4,000/8,000 Btu, two-stage electric heating element provides compartment heat. The system can be programmed to start automatically based on thermostat settings or time of day, the company said.

The ComfortGuard, powered by a two-cylinder diesel engine, is equipped with a Cummins alternator that produces 4,000 watts at 120 volts AC. It also produces up to 40 amps at 12 volts DC for charging the truck’s batteries and powering lights and fans. The APU also features self-diagnostics with a built-in microprocessor and LCD readout and, according to Bill Hathaway, the business unit’s marketing manager, offers a payback in about 18 months. Weighing 375 pounds, it is within the allowable gross vehicle weight variance for tractor-trailers equipped with APU equipment. More information is available at


These systems have their own maintenance demands, but they vary widely. Buyers need to make sure they can work on the units without voiding the warranty.

“Individual manufacturers have their own requirements for maintenance of their product,” says Freightliner’s McCorkel. “I would prefer if no maintenance were required. I’ve seen the APU manufacturers catch on pretty quick to achieving maintenance periods equal to the drive engine. Another significant facet is the complexity that results when you "add on" an anti-idle device to a vehicle with an electronic engine and data bus communication and splicing into the various vehicle systems. The interface and integration needs to be considered along with maintenance as another cost in the purchase decision.”

On-/off-board systems
Some suppliers have elected to offer systems designed to take advantage of or make easier the use of power sources outside the truck itself, for example, increased availability of electrical power in truck stops.

The Cab Power system, developed by Phillips and Temro Industries for shore power applications, is a series of pre-wired, modular components intended for installation in the interior of over-the-road truck cabs. The system includes a 120 VAC electrical load center, up to three receptacle outlets and a weatherproof inlet housing. An optional cable TV and telephone connection also is available. Acceptable power sources for the system are a direct connection to AC power or a DC/AC inverter connected to the truck’s battery. Factory installed or aftermarket kits are available.


Truck manufacturers are recognizing that a growing number of fleets are beginning to use APUs and are altering designs to accommodate these units. Peterbilt recently announced that it will incorporate a universal connection module to simplify an aftermarket auxiliary power unit installation for all models that can be equipped with sleepers.

“A growing number of fleets are using APUs, and there is a wide range of makes and models available in the market,” says Peterbilt’s Sproull. “Our new connector accommodates a wide range of APUs and allows for fast, simple installation of these alternative power sources. All of the necessary lines and wiring are provided. It saves about three hours of time when installing an aftermarket APU and avoids disassembly and reassembly parts of the sleeper box.”

Wayne Wissinger, product manager at Mack Trucks, says “Inverters and shore power are available on current production (pre US07) Pinnacle and Vision models via special request.” To avoid using valuable bunk storage space, Mack uses frame and/or battery box mounting arrangements for its Xantrex manufactured inverters. For ‘07 Pinnacle models, Mack also is introducing factory-installed Webasto sleeper air heaters.


Inverters or inverter/chargers represent another technology available to fleets that can help reduce idling. Inverters convert stored energy from a truck’s batteries into AC electrical power enabling drivers to enjoy electrical conveniences, such as laptop computers, entertainment systems and cooking appliances, in their cabs.

Inverter/chargers have that same capability, but they can also run the truck’s power loads off “shore power” while charging the vehicles batteries. They can even run space heaters or AC-powered HVAC systems to reduce or eliminate idling. The benefits of driver comfort and idle reduction have sparked a surge in sales of inverters.

Brian Lawrence, Xantrex’s OEM account manager, says his company’s sales through truck OEMs for factory-installed inverter/chargers nearly doubled in 2005. “We’re seeing excellent growth again this year,” he says. “It’s becoming an AC world for many drivers.”

Be careful, however, when purchasing an inverter.
“Inverters are one of the fastest growing add-ons in the trucking industry,” says Bruce Purkey of Rogers, Ark.-based Purkey’s Fleet Electric, “but you have to be very careful. A lot of times inverters will advertise they have shut-off protection. And they do, but it’s not what you think. They’ll often shut off at 10.5 volts which is done to protect the inverters not to protect your batteries. You won’t be able to start a truck at 10.5 volts. Look for an inverter which will shut off at 11 to 12 volts.”


There’s little doubt that a program to control idling is going to offer a welcome addition to a fleet’s profits, but just what can you shoot for?

“I would characterize 20 percent idle time as a pretty good fleet,” says Cummins’ Ellison. “At about 35 percent you’re a bit out of control. If you’re 50 percent or worse, you need to go find another job.”  


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