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Managing truck power systems
Nearly a century after those first pioneer truckers bounced down the road, the typical owner-operator rig places remarkable electrical loads on truck charging systems - loads never dreamed of even a decade ago.

When the first commercial truck sputtered to life in the early 1900s, there were no sophisticated electronic relays or even rudimentary concerns about battery life. All that was required was a hand crank and a driver with a strong arm. But it didn’t take many years for electrical “curiosities” — like headlamps — to find their way on board.

Why not idle?
Watson believes EPA legislation and local ordinances aim to make idling a thing of the past. “If you can still idle away the night where you’re at now, you might not be doing it this time next year,” warns Watson, noting that a growing number of states are issuing laws restricting idling to as little as 20 minutes.

Many companies are developing alternatives, including “shore power” in which trucks “plug in” much like an RV. Other companies are promoting stationary units that pump in heat or air conditioning through a window while providing electricity for plug in. Unfortunately, this infrastructure is years away from widespread application, and not every truck is fortunate to be near a travel plaza on a cold winter night when it’s time to bed down.

Before long, six-volt starting systems were commonplace. Years later, the 12-volt system opened up a new world of electrical accessories. Radios, CBs and dash-mounted fans — luxuries of their day — would be elementary by today’s standard.

According to Will Watson, vice president of sales for The IntraUSA Group Inc., a Tukwila, WA, specialist in DC power management technology, this evolution has placed tremendous strains on electrical systems, leading to increased maintenance costs and downtime. As a result, an all-out industry-wide sprint toward intelligent DC power management is now taking place. Why? Two key reasons: The proliferation of vehicle electronics and driver comfort items, and the growing trend toward anti-idling legislation.

Increasing electrical draw 
In today’s heavy-duty vehicle, advanced electronics such as satellite tracking and communications technologies, have been integrated in the cab, while additional loads under the hood, such as electronic engines, electronic ABS and electronic air conditioning soon will be joined by emerging steering- and braking-by-wire technologies. “Nearly everything in the cab comes at an electrical cost,” says Watson. “Add in simple items like blower motors and a stereo system to advanced electronics — and the cumulative effect is tremendous. We are incrementally increasing the demand for electricity to the point that truck manufacturers have responded by upgrading to 14.2-volt alternators. Rather than a solution, this shortens the life of components, such as headlamps. A high-current environment adds to the overall maintenance cost of maintaining the vehicle.”

Just a decade ago, a typical truck had a cumulative current draw of 30 amps. A typical over-the-road truck today can have current draws as high as 120 amps ... and that figure continues to rise. The effect is increasing electrical system failure across all segments of the trucking industry.

According to Jim L. Cade, vice president of maintenance for Ryder System’s 200,000-plus North American fleet, electrical failure is Ryder’s third largest cost area after fuel and tires. And surveys by TMC (Technology & Maintenance Council) show that Ryder is not unique in this aspect.

When the alternator stops turning
The biggest argument for intelligent DC power management comes into play when the ignition is turned off, the alternator stops charging and the battery takes over.

“The way we take electricity for granted is amazing,” said Watson. “Most of us don’t see much difference between plugging in a portable refrigerator in a truck and an appliance at home. Of course, the huge difference is that a truck is a closed system with finite power reserves, and the consequences of ‘living off your batteries’ are significant.”

Case in point: At an industry-wide average of more than $200 per occurrence, jump-starts are a growing problem in the trucking industry. “If you can start your truck at a low charge, you have very possibly drawn your batteries to the point of deep discharge, and that means significantly shortened battery life,” Watson warned. “In either case, an evening movie on the TV/VCR, microwave popcorn and an electric blanket can easily — and often does — cost hundreds of dollars.”

Watson emphasized this is just the tip of the iceberg. “When you add in the cost of downtime — lost business, penalties and dissatisfied customers — the true cost is huge,” he said.

In response to these problems, a growing number of trucks are coming off the assembly lines equipped with low-voltage disconnects (LVDs), an automatic switch that allows truckdrivers to enjoy appliances and comfort items during key-off periods while preserving battery power needed to start the engine.

Power management down the road
When Watson considers the potential for DC power management applications, he pauses for a moment and says, “Unlimited.”

Trucks will be started with a capacitor, and all parasitic loads will be powered by a hydrogen-based fuel cell. But that technology is years away, predicts Watson. What do we do in the meantime? “We manage our existing systems in the most intelligent manner possible, and that means understanding the significant and growing impact that DC power management can play as you strive to make the most profitable use of your truck fleet.”

The objective of all this technology is the same now and in the future as it was back when strong-armed truckers hand cranked their engines to a start, says Watson. “It’s all about moving that load down the road. Intelligent management of your truck’s power systems is another tool to maximize your up time.”