Modern Trucking Techniques
Idling your engine, part two
How do you eliminate the need to idle your engine?

by Paul Abelson, technical editor

Last issue, we began our examination of idling by discussing the reasons drivers do it, and its costs in both dollars and, possibly, in health. I was taken to task by a few members of the truckstop industry for suggesting that air at truckstops “is among the worst anywhere.” I stand by my words, but they are not limited to truckstops alone. Anywhere trucks gather in large numbers and idle, air quality is adversely affected.

For example, at the approach to the Peace Bridge going from Buffalo, NY, to Fort Erie, Ontario, trucks often wait in line for an hour or more with their engines idling. Residents living in the vicinity of the bridge and its approaches have asthma at a rate 60 percent greater than Buffalo’s general population. The Environmental Protection Agency (EPA) wants to know why. They have commissioned a major study to evaluate and quantify the risks from trucks idling in the vicinity.

government efforts
Since I wrote Part 1 of this series, the EPA has been assigned the role of lead agency in the government’s accelerated efforts to cut idling by trucks. The Department of Energy (DOE) had been examining truck idling wasting fuel, but evidently the White House wants the health aspects studied, too. EPA will have held a workshop at the Great American Trucking Show in Dallas (after deadline for this article). They are looking for industry input on ways to reduce idling. There may even be significant financial incentives (tax credits?) for installing anti-idling technology and hardware. We’ll have more on the EPA workshop in the next issue of Land Line.

The industry as a whole is starting to pay closer attention to idling. The Technology and Maintenance Council continues to look at costs and maintenance implications. Other trucking publications have articles on the subject, and the August 2001 issue of Fleet Owner magazine had a 16-page special section on idling. They indicate that 11 states have limits on all idling, ranging from three to five minutes, while in eight other states, various municipalities enforce their own limits.

don’t idle
There is no need to idle truck engines!

That’s about as strong a statement as I can make. Let me qualify it. There is no need to idle, if you have accessories on your truck to provide that for which you now idle your engine. Let’s take a look at some of these devices, to see how they operate and how they reduce the need to idle.

shore power
Many devices run on electricity, and that is in limited supply on trucks, even though we have multiple batteries. The best source of electricity is shore power, bringing household current into your truck and using it to do everything from charging your batteries, running your air conditioner or heating your engine, all while providing you with your creature comforts: hot food, cold drinks and entertainment through your stereo or TV/VCR. The problem is that far too few places where trucks stop, such as truckstops, rest areas, shippers and receiver’s yards, have either the wiring in place or the economical source of power to supply all the trucks that need it. The New York State Thruway and the Hunts Point Market are testing and evaluating IdleAire, a system that provides not only 120-volt alternating current (AC), but heat, air conditioning (A/C), cable TV, telephone and Internet service from overhead modules. Some government agencies have great hopes for this and other forms of truckstop electrification, but I still have my doubts about its long-term viability (see the Aug./Sept. issue of Land Line).

The next best way to get the electricity needed to eliminate the need for idling is to have an on-board generator. These devices have their own small diesel-burning engine that runs a generator directly. Most of these auxiliary power units share common systems with the truck’s engine.

For example, in many units the generator’s engine is cooled by running its coolant through the main engine block. That keeps the main engine warm enough to start in any temperature, while keeping the smaller engine from overheating. The workload on the smaller engine, from driving the generator and other accessories, is enough to keep it up at operating temperature. When the generator is off, coolant from the main engine keeps the smaller engine warm. Air conditioning may be provided by a second compressor plumbed into the OEM-installed system, using its evaporators and fans.

Other manufacturers keep their systems totally separate from the truck’s cooling and A/C systems. If one fails or is damaged, they say the other will not be brought down, but will continue to function. These generators use totally independent A/C systems, duplicating all the functions of the OEM installed A/C. Not every auxiliary A/C needs to be belt driven. With a surplus of electricity on board, compressors can be driven by electric motors, freeing them from having to be located at the front of the motor.

Depending on the size and capacity (generators are readily available to 6 kilowatts or more) generators can produce enough power to provide almost all the creature comforts you’ll ever need in your cab.

Inverters are excellent devices, but they are not without limitations. They convert 12-volt DC truck current to 12-volt AC household current. That lets you run AC appliances; anything from computers to TV/VCRs, coffee pots to hot plates, even vacuum cleaners. But remember, their source of energy is your battery, and with your engine off, its capacity is finite. You can easily draw your battery down too far, especially with resistance heaters in wintertime.

Even the best inverters are only about 90 percent efficient. The worst run at about 80 percent. That means if you have a 120-watt appliance (one amp at 120 volts, but 10 amps at 12 volts) it will actually need 10 percent more current from the battery. In this case, the input to the inverter must be 11 amps.

To determine how much you can run on an inverter without having to recharge your batteries, record how many amps each of the appliances draw at 120 volts. Each should have a U.L. (Underwriters Lab) plate indicating current draw. If it is given in watts, divide by 120. Multiply that number by 1.1 to make up for the inefficiency of the inverter (1.2 if it is less than industrial quality). Take that total for each appliance and multiply it by the number of hours you will use each one before you turn the engine again. Add the results for all the items. That gives you amp hours of usage at 120 volts. Multiply that total by 10 to get the number of amp hours at 12 volts.

Compare that to the total number of amp hours available from your batteries before they are too low to start your engine. Remember, the lower the outside temperature, the less reserve capacity your batteries will have. You may find you don’t have enough battery to power everything you’d like to use.

Fuel-fired heaters have the ability to generate a good bit of warmth without drawing our batteries down too quickly. They use electricity only to circulate air or coolant, and for a short time, to ignite the heater. It is the diesel fuel that provides the energy for heat. These heaters burn with a constant flame, much like a furnace in your home. Because the burn is continuous rather than intermittent as in an engine, combustion is far more complete and there are virtually no harmful emissions.

Today’s fuel efficient heaters can warm a fairly large sleeper all night at 0 degrees F, using a half gallon of fuel or less all night, while drawing barely more than two amps per hour (at 12 volts). While not as costly as generators, fuel-fired heaters are still not inexpensive items. They also lack the ability to do any cooling. Although several manufacturers have experimented with cold storage devices, they have not yet been adequately developed, at least in my opinion.

One of the best and most overlooked cooling devices, is an exhaust fan. Fans can be mounted near the highest point in the cab. They draw warm air out, bringing in cooler, fresher air. Exhaust fans available from marine dealers are rugged enough for use on trucks. A boat negotiating ocean waves or a Lake Erie chop experiences greater shock and vibration than a truck does.

The most economical way to get adequate heat for sleeping is to get a bunk warmer. These pads stay under you at night, converting their warmth under the blankets, and conducting much of it directly to you when you’re under the covers.