Auxiliary Power Unit Update

Auxiliary Power Unit Update

APUs are becoming commonplace, with more and more fleets either installing aftermarket units or opting for factory-installed units when ordering new trucks.

APUs are becoming commonplace, with more and more fleets either installing aftermarket units or opting for factory-installed units when ordering new trucks.

104672AIIdleTru_00000056023With a host of proven advantages—the most notable of which is fuel savings—auxiliary power units are becoming commonplace, with more and more fleets either installing aftermarket units or opting for factory-installed units when ordering new trucks.

Simply stated, an APU is an onboard solution designed to provide climate control and creature comforts to drivers of trucks with sleeper cabs—all without the need to idle the truck’s engine. The units contain small generators and climate control components that are mounted to the truck and provide heating, cooling and 110v power to drivers.

Because APUs eliminate engine idling, the result can be a dramatic decrease in a truck’s non-driving fuel consumption (more than 80%) and a corresponding reduction in diesel emissions, according to a recent case study by David Hancock, CEO of APU maker Hodyon. The study, titled “The Case for Shorepower Truck Electrification: Reducing OTR Big Rig Emissions and Fuel Usage in the U.S.,” addresses a Department of Energy (DOE) grant designed to reduce emissions on long-haul Class 8 trucks and locomotives.

Representatives from other manufacturers agree: Each person polled for this article listed fuel savings—and by extension, cost savings—as the number one advantage APUs offer fleets. But there is even more to consider.

John Dennehy, vice president of marketing and communications for Espar Heater Systems, says other benefits include driver comfort and greenhouse gas reduction; it also boils down to good publicity for a fleet. “Freight companies become carriers of choice for those companies that have carbon footprint initiatives,” he adds.

Bergstrom’s Bill Gordon, vice president of aftermarket and Nite sales, notes APUs also help fleets comply with anti-idling regulations, which vary widely between states, counties and even from city to city.
Summing it all up, Paul Barbaro, APU product manager for Thermo King, adds, “APUs reduce overall fuel consumption—which equates to dollars for the customer—provide driver comfort in no-idle zones and extend the hotel load capabilities of the driver’s sleeper area.”

Bergstrom's Nite Phoenix
Bergstrom’s Nite Phoenix

Adding to the widespread adoption of APUs is the federally-funded Shorepower Truck Electrification Project (STEP), administered by Shorepower Technologies and Cascade Sierra Solutions. The grant program is two-fold: Shorepower Technologies is working to install electrical connections at parking places in truck stops around the country, while Cascade Sierra Solutions coordinates 20% off rebates for onboard equipment upgrades, including shorepower-capable APUs.

APU Trends
APUs range from diesel engine designs to hybrids to battery-powered units.

Diesel units contain a small engine that draws fuel from the truck’s fuel tank and runs as needed, providing a virtually endless power supply for in-cab appliances. While it has an effect on a fleet’s miles per gallon figure—since it is, after all, using fuel to operate—a diesel APU consumes far less fuel than idling a truck for long stretches of time. There is some maintenance required for diesel APUs, including oil and filter changes, belt replacement and other periodic service.

Battery-powered APUs offer a true zero-idle solution. The units are charged while the truck is in operation, often in as little as five to six hours, and serve as a power source while the truck engine is turned off. While battery-powered APUs use no fuel, they do have a time limit for providing in-cab power. In general, units offer at least 10 hours of runtime, and many have “auto start” features that “sense when the batteries are close to the depth of discharge and will shut the system down and automatically start the truck engine to charge the batteries in a relatively short amount of time,” says Bergstrom’s Gordon.

He adds that for battery-powered APUs, a simple filter change is the only preventative maintenance, aside from the need to change batteries at some point. “They do not burn fuel, and there are no belts or other parts that inherently need maintenance or replacement like on a diesel-powered APU,” Gordon explains.

According to Thermo King’s Barbaro, while the basic technology has not changed in recent years, the efficiency rate of the equipment and the options being offered to address customers’ applications and needs both have improved.

“The capacity (BTUs) of the battery-powered APUs has come a long way through the use of more efficient components and advances in battery technology,” says Bergstrom’s Gordon, who adds the company offers two aftermarket units: the Nite Plus and the Nite Phoenix. The Nite Plus offers 4,600 BTUs of cooling, while the Phoenix system offers 7,500 BTUs. “Over 30% of our aftermarket sales are the Nite Plus, which tells me this unit has sufficient cooling capacity for some segments of the market, while the Nite Phoenix is designed for the very hot areas of the country, such as Phoenix.”

Espar’s Digi-Max D1000
Espar’s Digi-Max D1000

According to Hodyon’s Hancock, there still is a certain amount of reluctance from fleets that may have had previous negative experiences with APU quality and consistency. “Therefore, we have a fleet trial program that is designed to help them overcome the fears from those previous bad experiences,” he adds.

“Most customers who have tried a quality APU tend to keep investing in them because the payback proposition remains very robust with today’s fuel prices,” Thermo King’s Barbaro adds.

APUs are thought of as a year-round option, providing heating and cooling for driver comfort. To that point, Espar Heater Systems and Webasto Product North America focus on fuel-operated heater systems.

“Espar products are somewhat classified differently in that they are not true APUs, but rather fuel-operated heater systems,” says Espar’s Dennehy. “Our heaters are smaller and more efficient today, with less parts. We also have developed a new timer, which is state-of-the-art and lets drivers and fleet managers program a number of presets to meet specific conditions.”

“We have partnered with several APU manufacturers to sell them in conjunction with their engine-powered and battery-powered APUs,” says Josh Lupu, marketing manager for Webasto. “We are finding that top APU manufacturers are offering auxiliary heaters, such as our Air Top 2000 ST, to their customers along with their APU to create a year-round solution.”

He adds the unit can operate for more than 22 hours on a single gallon of fuel, reducing idling, emissions, and engine wear and tear

Hodyon's Dynasys APU
Hodyon’s Dynasys APU

Cost Savings
While the price of an APU can range from $6,000 to $8,000, plus installation costs, there is a proven return on investment, according to system manufacturers.

Hodyon’s Hancock says the suggested retail price for an installed Dynasys unit is roughly $8,500, but the annual fuel savings reaches $8,000 and the unit will last up to five years.

Espar’s Dennehy adds the typical installation “takes four hours by a trained representative, but these systems are pretty straightforward and can be installed by the end user if he or she has some mechanical background.”

Gordon explains the up-front cost varies depending on options chosen—battery box inverters, chargers, heat, shorepower, batteries, etc.—but that Bergstrom offers a payback calculator on its website ( to determine ROI.

“The up-front cost varies significantly,” Thermo King’s Barbaro adds. “If properly specified to the customer’s application, an APU does provide a significant payback.”

From fuel and cost savings to emissions compliance and increased driver comfort, APUs continue to be an important consideration for today’s fleets. There are many choices available; see below for some of the latest products on the market.

ProMax APU by Dunamis Power Systems
ProMax APU by Dunamis Power Systems

Bergstrom says its Nite Plus (4,600 BTUs) and Nite Phoenix (7,500 BTUs) battery-powered, no-idle APUs save fuel, keep drivers comfortable and help protect the environment. Both models are CARB-approved, comply with all idle restriction laws, and install easily under bunk in eight to 10 hours, according to the maker. The Nite Plus offers 30% higher cooling capacity than the original Nite system using less battery power, and new heat exchangers and redesigned airflow result in better, more efficient penetration and cooling. Bergstrom adds the Nite Phoenix features a new LCD digital user interface and battery monitoring system, as well as on-board service diagnostics, automatic temperature control and a check filter function.

Espar’s Maximum Control family of heater controllers includes the Multi-Max F1000, to serve the needs of the Hydronic line of engine coolant heaters, and the Digi-Max D1000, to serve the needs of the Airtronic D2/D4 bunk heaters. The maker says the Multi-Max F1000 gives fleets complete control over their pre-heat coolant heaters by introducing a desktop programmer and a Micro SD card slot, which allows programming for as many as four distinct events per day; a high temperature disable set point; a maximum manual run-time; a low voltage disable set point; a preferred PM interval; and an exercise scheduler. The Digi-Max D1000 gives drivers maximum control and features a larger display screen, easier to operate controls, added descriptive fault code messages, and more, the company adds. The unit also features a maximum run time limiter, customized PM schedule alerts and a programmable low-voltage shut-off.

Thermo King's TriPac e
Thermo King’s TriPac e

Hodyon says its Dynasys APU offers the power that truckers need in a compact package. The lightweight unit is designed to be easy to install and maintain, offers significant fuel savings—an average of one gallon per hour while idling—and enables driver compliance with all non-idling laws, according to the maker. The Dynasys APU offers 6kw of power, more than enough to support both HVAC and other electrical appliances in the cab. It also is available with shorepower, which provides the additional flexibility of allowing the HVAC to be plugged into any 110-volt outlet and to work independently from the APU engine for optimum performance and fuel savings, with minimal noise, Hodyon adds.

The ProMax APU by Dunamis Power Systems offers 33,000 BTUs for both heat and air conditioning, as well as 650 CFM of air flow. The unit features a rugged, modular construction that mounts directly to a truck’s frame and an APU auto-start for low battery protection. An optional inverter provides in-cab power and shorepower hook-up capability. The maker adds the unit is compliant with all existing no-idle regulations, and maintenance can be performed by a fleet’s regular mechanic with the same service intervals as the engine.

Thermo King
Thermo King says its TriPac e battery-based electric APU for Class 8 sleeper cabs provides quiet, clean heating and cooling without idling the tractor engine. The TriPac e system is CARB exempt and provides an environmentally aware solution that delivers significant fuel savings and zero emissions (in non-heat modes), the maker adds. Because the tractor engine is not running, users can greatly increase maintenance intervals, saving time and money.

According to Webasto, its Air Top 2000 ST fuel-operated auxiliary heater can operate for more than 22 hours on a single gallon of fuel. The company says the unit is ideal for most Class 8 sleeper cabs, offering 7,000 Btu/h of heat output in a small package. It is low maintenance, service-friendly and the most efficient air heater on the market, Webasto says, adding the unit can pay for itself within months. The Air Top 2000 ST is CARB approved, EPA SmartWay verified, and carries a two-year/2,000-hour warranty.

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