In The Shop
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Someday soon, truckstops will be silent, thanks to on-board, engine-off climate control. (Photo by Jim Park)
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5/5/2010
APU Maintenance
By Jim Park, Contributing Editor
No-idle climate-control systems are here to stay after years of sluggish growth and slow market acceptance. The cost of idling, coupled with no-idle mandates in more than half the states in the country, have pushed fleets and owner-operators alike past the need for a sparkling return on investment. Now, they're willing to look at systems that keep drivers happy and comfortable in areas where big diesel engines aren't allowed to idle for more than five minutes. In most cases, the ROI is there, but payback is slipping down the priority scale, giving way to compliance with anti-idling regs and driver satisfaction.
Operators have a choice today of battery powered cooling systems combined with a fuel-fired heater, or the diesel-engine-based systems that either provide power for an electric AC compressor or drive a compressor independent of the truck's HVAC system. The systems have come a long way since the first commercially available units hit the streets in the late 1980s. Upfront costs have come down significantly, and reliability and efficiency have both improved as well.
As is the case with anything mechanical, no matter how well it's put together, it won't run forever without a little attention.
Itamar Levine, the director of maintenance and purchasing at Bison Transport in Winnipeg, Manitoba, says when his company first went down the APU road more than a decade ago, they were lasting only weeks because of the corrosive anti-icing material used on highways.
"Without exaggerating, each unit we had went through four of five radiators in three years," he says. "Exhaust systems would last two or three months before they flew off the truck. We had a technician in each of our shops who did nothing but service and repair APUs."
Levine notes with some relief that current models have proven much more reliable. So while each APU may not need as much parts and service as it used to, because there are more APUs on the road today, it means there's strong and growing demand for replacement parts, consumables, and service.
Levine's advice for a long and happy relationship with an APU is to buy a premium product, and service it with premium parts.
"Synthetic oil, for example, will improve cold starting capability, and ensure good lubrication, just in case you go over the service interval," he says. "Stick to the recommended maintenance intervals, don't scrimp on the materials, and maintain a good relationship with the product's service manager."
Routine maintenance
Engine-based systems are more maintenance-intensive than battery powered systems, but both require a little care and attention every now and then. Depending on the manufacturer's recommended service intervals, the engine-based systems will need at least oil, filters, and possibly drive belts.
APU maker Carrier recommends for its ComfortPro APU an oil and filter change at 1,000 hours, along with a valve-lash adjustment. There are also specific points that need cleaning and/or inspection, such as the radiator and condenser fins. At 500 hours, Carrier suggests inspections of the fuel system, coolant hoses and clamps, belt tension and alignment, a chassis inspection including the exhaust system, mounts etc., and an air filter inspection.
The 2,000-hour inspection is a more comprehensive service interval requiring, among other things, examining the performance parameters of the fuel injectors, generator and alternator output, starter, and HVAC system.
In general terms, Carrier's Dean Lande tells us, "The 1,000-hour service is a six-month interval for a typical over-the-road operator, the 2,000-hour service is an annual event."
Established maintenance intervals aside, to keep an APU running, you have to consider where it lives - hanging on a truck frame. You won't find a more hostile environment anywhere, with constant vibration, occasional jolting impacts, corrosive road spray, and extreme heat and cold.
Most APU failures can be traced back to one or more of these factors. Since you can't eliminate them, the best you can do is guard against component damage.
That means keeping a close eye out during regular service inspections for physical problems such as cracks forming on the component mounts, and around the radiators, mufflers, and other external bits. Be wary of possible contamination and corrosion, especially on the seals and connectors.
Dwayne Cowan, product manager for auxiliary power units at Thermo King, suggests keeping a close eye on the mounting brackets and the connectors leading to and from the unit.
"Anything you can do to reduce costs is going to improve the ROI, and chassis inspections and maintenance are high on the list - in addition to the scheduled service events," he says. "Our coolant and refrigerant loops are factory sealed and require no routine maintenance, but don't ignore them. Leaks can develop, hoses can become chafed, and any of that could result in failure."
There is usually about 2 pounds of refrigerant in the system, and unless a leak develops, there's no need to top up the systems. If the refrigerant level needs to be adjusted, federal law requires the work be done by an EPA-licensed HVAC technician with the proper tools to avoid accidental refrigerant discharge.
"Regular and thorough washing is highly recommended. Electrical connections should be sealed with dielectric grease and then left alone. Opening the connector renders them prone to incursion," Cowan adds.
In addition to the chassis and engine service, PMs should include a check of the condensate drain to ensure the fittings aren't clogged. If the customer has a split system with an external condensing unit, inspect and clean any debris from the condenser coil to ensure good air flow, Dometic advises.
Battery-powered systems, on the other hand, require few consumables and service requirements are basically just visual inspections.
The next wave
Since it's the engine that requires the majority of the maintenance on a diesel APU, take away the engine, and you're left with batteries. Stand-alone HVAC systems do not use traditional lead-acid batteries, so you don't have the usual battery maintenance, either. Instead, Advanced Glass Mat (AGM) batteries are the power supply of choice, and these require no maintenance beyond ensuring the connectors are tight and the cable is in good condition.
In short, there's not much that can go wrong with a battery-powered system.
"There's not much on the original Nite system that could fail, except perhaps a fan motor or something," says Bill Gordon, Bergstrom's national director of aftermarket. "Our new Nite Phoenix system has an air filter that requires annual replacement, but that's really it."
Bergstrom was one of the pioneers in battery-powered on-board climate control systems. Its Nite HVAC system was adopted by several OEMs as a data book option. The company raised the stakes this year, introducing the first no-engine climate control system powered by lithium-ion battery.
Gordon says the single Li-ion battery is 63 percent lighter (110 pounds) than a three-pack AGM system, takes up 20 percent less space on the truck, and it produces 16 percent more power. Additionally, the Li-ion battery has zero memory effect, which helps maintain optimum charge and recycle performance over a longer lifespan than AGM batteries.
While Gordon admits the Li-ion batteries are more expensive upfront, he says the system remains competitively priced, and will actually prove less costly over the life of the unit.
"When you look at the efficiency of the system, and the replacement costs and life cycles of AGM batteries, a Li-ion battery makes the value proposition. We cool for longer, for less, we charge faster, and over the life of the system, we're about 20 percent less expensive," he says.
In a revealing move, Thermo King released a battery-powered version of its Tri-Pac APU at the Mid-America Trucking show this year, tipping its hand in which direction it thinks APU power systems are moving.
"There's little doubt that diesel-powered APUs have had their day in the sunshine," says Will Watson, president of Will Watson and Associates, LLC, a business development company that helps clients through strategic market analysis. "Real growth will be in non-engine-based systems, such as thermal storage systems, battery-driven systems, shorepower systems, and looking a little further out, fuel cells."
The most significant weakness with a battery system at this point, Watson says, is storage capacity. The batteries will only hold enough charge for limited use, like eight to 10 hours. But if the system isn't fully charged, they won't last that long. This is a problem for truckers whose operating cycles can't guarantee a day's driving to provide a complete charge. Even with a full charge, they're good only for one night. That's a problem for a weekend layover in hot weather.
The solution, Watson believes, is truckstop electrification (TSE), where trucks can plug in at a truckstop, terminal or warehouse facility.
"Once these installations expand - and they will - we'll be able to run the electrical HVAC system off the grid, while charging the batteries," he says. "That one step will solve several of our problems at once."
Webasto has shown its faith in expansion of TSE by launching a version of its BlueCool Truck technology designed for a shorepower hook-up. Because it uses electricity from a land-based source, the BlueCool Hybrid can produce cool air indefinitely, unlike battery-powered systems that need to be recharged by the engine after a single rest period.
"The BlueCool Hybrid APU can also operate without shore power, keeping the bunk area cool for up to 10 hours by using energy that was stored during highway operation," says John Thomas, general manager of Webasto's commercial vehicle division.
Since most of these systems also include a diesel-fired bunk heater for winter operation, there are minor bits of maintenance to consider.
John Dennehy, the vice president of marketing and communications with Espar Heater Systems recommends running the heater for about 15 minutes at least once a month, even in the summer months, and checking the fans and blower motors periodically.
"We also suggest users check and clean the glowpin once a year, and watch for soot build-up in the combustion area," he says.
Diesel powered APUs may have the upper hand at the moment in terms of performance and duty cycle, but battery powered systems are the ones to watch going forward.
With solutions emerging other than adding banks of heavy, bulky batteries, watch for greater uptake of non-engine-based anti-idle systems. Because they are electrical, there will be fewer maintenance opportunities - but there are some opportunities in helping customers get the most out of their investment.
More bang for the buck
Until someone comes up with an APU additive that squeezes more BTUs from the system while reducing emissions, truck owners will have to rely on more traditional performance enhancements - and there may be some opportunities for the distributor/service provider in helping the customer do it.
Most truck sleepers are insulated to an R-value of approximately 1 to 1.25 - compared to insulation value of R30 currently required in most new home building codes. Even the "cold-weather packages" offered with some new trucks only have insulation values of R2, Dometic tells us.
Adding insulation to the roof and back walls of the sleeper or under the floor would be a relatively simple modification that will lessen the workload on the cooling system. Skylights and windows can be covered with reflective material to keep sunlight out, and heavier curtains separating the sleeper from the cab would shrink the space the unit has to cool.
Additional batteries can be added to extend the uptime on a full charge, if the trucker can accommodate the space and the weight. Consult the manufacturers for particulars here, as there are right and wrong ways of beefing up the electrical storage capacity.
A standard 135-amp alternator with an internal regulator is adequate for normal current draws, but would be inadequate for the heavier charging requirements for a battery-powered air conditioning system. Dometic, for example, specifies a high-output alternator with an external regulator. The regulator acts as a three-stage battery charger that charges and protects the batteries through numerous discharge cycles.
If you upsize the battery bank, you'll probably need to upsize the vehicle's alternator as well. And don't overlook the cabling requirements. Higher output alternators may require heavier cable, particularly if the batteries are located any distance from the charging system.
Inverters must be matched to the application and load, so don't think you can get away with an off-the-shelf product. Take care when spec'ing an inverter, and clear the move with the engineering people before installation. A great number of vehicle fires have resulted from improperly wired inverter/charging installations.
From the April/May 2010 issue of Heavy Duty Aftermarket Journal.
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