Truck Topics

APU Basics You Need To Know

Idling may be part of the professional driver's life, but this too shall pass. With strict no-idle laws in some states and local communities, there are more reasons than ever before to investigate idle-reducing technologies.

And, if the threat of a police citation and the fines imposed aren't motivation enough to shut the engine down, then today's ever-escalating fuel prices must surely be. Because the typical heavy-duty engine at idle consumes upwards of a gallon per hour, the cost of staying comfortable in the cab/sleeper has increased dramatically.

Enter the Auxiliary Power Unit (APU).

The demand for APUs began in the 1980s, when companies began building and marketing large (7 to 14 foot) camper/sleeper cabs for long-haul diesel trucks. Standard truck heating and cooling systems were not sufficient to heat and cool these large units. Auxiliary power was needed.

The APUs needed for these trucks require at least 4kw and as much as 8kw of power. As such, all of the APU manufacturers adopted 7 to 16 HP diesel motors that could produce enough power to meet these requirements.

APU's can offer heating, air conditioning, engine warming, battery charging and plenty of power for comfort items such as TVs, computers and coffee makers.

Using a small engine to do the same environmental work as the main engine means far less fuel consumption - about a pint per hour.

Long-favored by owner-operators who are painfully aware of fuel costs, APU's are being utilized by many of today's trucking fleets. Fuel savings are the number one reason, of course, but driver comfort also translates into driver retention.

But, say the critics, APUs can be expensive and they require installation by qualified technicians along with routine maintenance. However, compare that cost with an idling main engine gulping down $5.00/gallon fuel every hour and it won't take long to see return on investment.

At the same time, using an APU will greatly extend the life of your main diesel engine, significantly extend its oil change intervals and enhance the truck's resale value.

Different designs
Ray Lawrence of Espar of Michigan explains that
many APUs are integrated into the truckís cooling and air-conditioning systems, while a generator - referred to as a genset - is defined as a "stand-alone" device.

He explains, "The integrated APU system generally consists of a small internal combustion engine (usually diesel) equipped with a generator and heat recovery system to provide electricity and heat. For air conditioning, an electrically powered air-conditioner unit is normally installed in the sleeper, although some systems use the truck's air-conditioning system."

Lawrence goes on to say that because most auxiliary power units are integrated directly into the truck's systems, they offer a high level of convenience. In addition, APUs are a proven technology that is widely available and is even sold as an option on some new trucks.

Nearly all APUs and gensets use the truck batteries for starting which provides excess cranking power. They use one of the truckís fuel tanks for their fuel.

ROI
Most APU makers say the devices can pay for themselves in less than 2 years, based on the current price of fuel. Prices for the systems range from around $7,000 to more than $10,000.

Two of the most widely-used APU's are from Thermo King and the Canadian-based Rigmaster Power.

Thermo King's TriPac APU is powered by a Thermo King 2-cylinder engine and the unit 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. The TriPac weighs in at 430 lbs.

www.thermoking.com.

Rigmaster's "stand-alone" APUs are equipped with either a 2-cylinder Caterpillar or Perkins engine. The system features a 6-kW generator and 60-amp alternator that delivers battery charging power and 120 volts A/C 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. The Rigmaster unit tips the scales at 431 lbs.

www.rigmasterpower.com.

Espar of Michigan's Ray Lawrence says that because every truck is different, every APU installation is different and should be left to the professionals. An improper installation performed by unqualified personnel could very easily void the warranty from many manufacturers.

Lawrence: "Regardless of the anti-idling system an owner-operator uses, if he can save fuel, it's all to the good."

"Anti-idling technology can pay for itself in arelatively short time period."

www.esparofmichigan.com

A number of states have enacted idling regulations in some form at the state, county or city level with fines ranging from $50 to $25,000. A complete listing can be found at www.atri-online.org/research/idling/Truck_ldling_Regulations.htm

The U.S. Department of Energy's (DOE) Clean Cities program provides a listing of Federal and State programs that offers funding incentives for idling reduction projects. These can be found at www.eere.energy.gov/ cleancities/idle/incentives.html

The West Coast Diesel Collaborative has a comprehensive state listing of grant and loan programs available to purchase or apply for a loan for onboard idling reduction equipment. Visit www.westcoastdiesel.org/programs.htm