TAMPA, Fla. – Anti-idling laws may be good for the environment and bids to save fuel, but they represent a challenge for trucks that have traditionally put the power of an idling engine to work. Even the largest alternators can struggle to keep up with the demand of batteries in light- and medium-duty work trucks, which are expected to energize everything from electric-over-hydraulic pumps to cranes, laptop computers, snowplows, and liftgates.
“I need to power electric loads at the work site, but the truck engine must shut down. So how do I ensure I have enough power to run my devices and still start the truck at the end of the day without killing the life of my batteries?” asked George Mayhew of Verizon Fleet Operations, during a presentation to the Technology & Maintenance Council. “It now comes down to batteries and looking more deeply at what those loads are.”
Each tool can place a unique demand on a truck’s electrical system. A low-current inverter delivering 300 watts or less will typically support the charging of a laptop or hand tools, and even provide chassis lighting or emergency lighting. But cranes, liftgates, aerial lifts, work lights and some emergency lights will likely require high-current models.
Part of the answer to their power needs will come in well-informed battery choices.
At first glance, the batteries all look the same. “The batteries are all 13-by-seven-by-nine, and they all come in black cases with black covers,” said Jeffrey Coleman of East Penn Manufacturing. But they are equipped for different roles. A flooded lead acid battery is used for starting and boasts a deep cycle; a Sealed Valve Regulated Lead Acid absorbed glass matt (AGM) battery will fill dual purposes; and gel batteries will only offer a deep cycle. Those used primarily to crank the engine need to provide instantaneous power, in a low-resistance design that delivers 650 to 1,125 cold cranking amps and a reserve capacity that falls somewhere between 140 and 195 minutes.
“They are not designed for high-cycle use. They’re designed to crank something,” Coleman explained. In contrast, a dual-purpose battery can combine the instantaneous power and deliver power over time. But there are sacrifices. They will offer 650 to 730 cold cranking amps with reserve capacities of 190 to 200 minutes. Meanwhile, a deep-cycle design used to run something like a liftgate may offer 650 cold cranking amps and a reserve capacity of 190 to 200 minutes, but would struggle to start an engine.
Ranking batteries in terms of life, the best option is a gel design, followed by an AGM, a flooded deep-cycle battery, flooded dual-purpose batteries, and flooded starting batteries. If the battery is used for starting and cycling, the ranking shifts in order to AGMs, flooded dual-purpose, flooded starting, flooded deep cycle, and gel batteries.
“Unless you’re isolating battery packs within a truck, you don’t want to mix these technologies in the same battery packs,” Coleman warned, noting how this would sacrifice battery life. But there is still a chance to use a different style of battery devoted to a tool like a liftgate.
Regardless of the battery, short trips and limited idling time can be a challenge for any alternator. “If batteries are not fully recharged during the driving to the next stop, the batteries will continuously operate in a discharged state,” Coleman said. That will shorten the battery life.
Lou Stumpp, Navistar’s national account manager, fleet service, admitted that the challenges are relatively recent. “I don’t remember dead batteries being a real problem 30 years ago unless the lights were left on,” he said, noting how trucks once served by 35-amp alternators are now typically equipped with 120-amp designs.
But the electrical demands have steadily increased, as batteries have been asked to feed everything from second-generation ABS brakes to collision avoidance systems, car-like HVAC systems, and controllers for engines, electronics and transmissions. That doesn’t begin to address additional tools such as business band radios, printers, point-of-sale tools and other creature comforts. “Most all of them have the same male plug that fits into a cigar lighter,” he added.
To compound matters, current will always take the path of least resistance. “Unfortunately, the battery is the lowest guy on the food chain,” he explained. Even though the first 70% of the battery’s charge will return quickly, the final 30% represent a “long, long uphill road and that’s the range we typically operate in.”
Still, batteries are sometimes blamed for problems they did not cause. For example, the parameters on a timer may be responsible for shutting down a liftgate earlier than expected. “Most of (the liftgates) aren’t steady-state. They’re intermittent,” Stumpp says. “If you give the battery time to rest, it will recover.”
Options to help maintain the all-important supplies of electricity can include alternators with remote voltage sensors that monitor voltage at the battery, low-voltage disconnect devices, or individual load-shedding devices. Just make sure that the settings are above the levels needed to crank the engine, Stumpp said.
“Do the simple things first,” he added. That begins by understanding voltage drops, and ensuring the starting and charging system is healthy. Battery terminals should also be cleaned on a regular basis. “A voltage meter and a wire brush will save you a lot of money,” he said.
Energy savings can also be realized by choosing equipment sizes based on actual needs. The choices of a battery for a liftgate should consider the number of cycles, deliveries in a day, driving time, distance between stops, the gate’s rated capacity and temperature, noted Daniel Cox, technical support manager at Midtronics. And ongoing maintenance on the gate should involve checking the pump and hydraulic lines for leaks, inspecting fluid levels, and simply observing the operation.
“Maintenance can’t fix a design that can’t possibly succeed,” he said. “Think out of the box a little bit,” he added, referring to other devices. “What about shore power? Plug it in!”
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