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Today's sleepers have more in common with RVs than the boxes and bunks of yesterday. Creature comforts range from televisions and refrigerators to air conditioning and laptop computers, drawing on the...

Today’s sleepers have more in common with RVs than the boxes and bunks of yesterday. Creature comforts range from televisions and refrigerators to air conditioning and laptop computers, drawing on the electricity that comes from truck batteries and power inverters.

But the comfort comes at a cost. Each appliance adds to the strain on the truck’s electrical system, and the added loads encourage extended idling to ensure engines will crank after a night at the truck stop.

“The key to this whole thing is batteries,” says Carl Smith of Sure Power Industries. “And if I can’t start my engine in the morning, I’ve defeated the purpose.”

Of course, components are available to manage the loads. Load shedding systems can turn off various systems once batteries drop below a pre-determined point. Cruder vehicle disconnect systems simply turn everything on or off. Meanwhile, there could also be an argument for auxiliary battery banks that are widely used in boats and RVs, Smith says.

But several approaches to powering these devices promise to lift some of the load off your truck. Auxiliary power units (APUs) that use less fuel than an idling engine are able to offer the required electricity to drive these systems, while “truck stop electrification” projects in selected U.S. sites are offering truckers the opportunity to plug into supplies of everything from electricity to cable TV.

Truck makers have committed to offering self-sufficient sources of alternative power — or connections for shore power systems — by 2008, says Mike Meleck of Phillips and Temro, noting that the goal is to provide heat, air-conditioning and power for appliances that can last an entire off-duty cycle.

Schneider National, Freightliner and Webasto are testing a mobile system that retains cool air and provides a diesel-fired air heater. International, Espar and WalMart’s fleet are experimenting with a system that includes a diesel-fired heater, engine pre-heater and roof-mounted air conditioner powered by auxiliary batteries. Still a third test involves International, Caterpillar and Cox Transfer testing Caterpillar’s MorElectric system that includes an AC compressor, HVAC unit, high-efficiency generator to replace the alternator, and an auxiliary power unit that consumes a mere 0.75 litres of fuel per hour.

On-board a truck, an APU can provide power without any external hook-up. The systems tend to be equipped with one to three cylinders, and consume an efficient 0.5 and 1 litres of fuel per hour, says Will Watson, vice-president of sales and marketing for Auxiliary Power Dynamics. Related options vary from a trickle charger to maintain existing batteries, to an oil pump that can pre-lube an engine to eliminate dry starts.

The units tend to be mounted to frame rails behind fuel tanks tank, with air conditioning condensers found at the back of a cab. (They’re often enclosed in a step box, or mounted behind the rear wall.) And the APU tends to be fairly simple in design — with an alternator, auto belt tensioner, air compressor, oil pump, AC compressor and a heat exchanger.

The HVAC power can vary from 9,000 to 30,000 BTUs, while units can also deliver 3 to 7.5 kilowatts of electricity, have an alternator delivering 30 to 180 amps, and be installed between 10 and 32 hours, at prices ranging from US $6,000 to US $13,000.

The Auxiliary Power Units could also become smaller if manufacturers can improve the insulation and windows on trucks, adds Dr. Linda Gaines of the Argonne National Laboratory, which has released several studies on the effects of idling. “If these devices didn’t weigh 400 lb., they may be more eager to put them on.”

Transport Canada has supported devices that are attached to trucks, subsidizing bunk heaters that require less fuel than an idling engine, government funds in the U.S. are being spent on “truck stop electrification” efforts because states — the source of the funds — want to ensure the benefits are all enjoyed within their borders.

TravelCenters of America, for example, is in the midst of a major push to offer IdleAir services in areas that provide government funding, says Peter Green, senior vice-president of development and franchising. Three TA truck stops in Texas, one in New Jersey and an additional site in Tennessee now offer the systems, while another 25 locations are expected by the end of the year.

While these systems include a supply of air conditioning, 120-volt power, entertainment systems (such as cable TV) and communications systems (local phone service), other offerings range from simple supplies of electrical power, to extensive on-truck systems. Surepower Pedastles, for example, offer similar features but require truck owners to fit their equipment with systems that include everything from a wiring package and heater, to a power inverter and extra batteries.

But truck stop electrification can be an expensive proposition. In-truck Surepower equipment can cost anywhere from US $200 to US $3,500, while it can cost about US $15,000 to equip a parking space with IdleAir services. When first launched, the efforts also tend to require as many as 15 to 20 staff members per 100 parking spaces until users know how to work the systems.

Gaines admits that the efforts continue to be limited to a small number of spaces, and have so far been unable to expand without the help of government grants.

“This is still any iffy technology from what we can see,” she says.


A primer on truck stop electrification systems

Cab Power – from Phillips and Temro Industries offers pre-wired components that rely on electricity from a shore power connection. Added to an Auxiliary Power Unit and block heater, it can provide heat, air conditioning and electricity. The load center includes a Ground Fault Circuit Interrupter, circuit breaker and flush-mounted receptacles, while the system can also be connected to inverters, electric HVAC units and generator sets.

Proheat – Teleflex offers product including the CCU Shore Power unit for electrified truck spaces, including an HVAC system and connection that can draw electricity from a standard 110V/15 Amp household extension cord. The heating and cooling doesn’t require a generator, while the shore power kit includes a battery charger and transfer switch.

IdleAir Technologies – A structure at each parking space offers a stand-alone HVAC unit and other services, with a hose and cables that connect to a user interface that fits into a cab window fitted with a $10 adaptor. The module delivers heat and air conditioning, Internet connections, local telephone service, satellite television, movies on demand and computer-based interactive driver training, as well as 110-volt outlets inside and outside the cab to power everything from appliances to block heaters.

Shurepower – includes tractor connection kits that cost from US $200 to US $2000 depending on the services you want to access at an equipped truck stop, such as 120 VAC power, Internet, WiFi, telephone and cable television.

Truckpower – Xantrex Technology’s solution couples its Truckpower inverter and charger to Cab Comfort’s Duo-Therm heat pump. The AC power comes from truck batteries, or a shore power connection. (A built-in battery charger recharges the batteries when a connection is available.) A separate 12 V power supply offers DC power without depleting batteries. Cab Comfort systems include an electric heat pump.

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