Powering Liftgates

A single, 310-watt eNow solar panel installed on a cab roof. (eNow Energy)

Liftgates used a few times a day on over-the-road hauls often run off the truck’s battery and experience few power problems. But delivery routes with multiple stops may not provide enough battery charge time, causing trucks not to start and liftgates not to work.

Advances in batteries and charging systems, as well as the use of solar panels, are helping to change that.

“Typically, the charging system on a tractor-trailer is the alternator,” said Bruce Purkey, founder and former chief creative engineer at Purkeys, which manufactures battery solutions for heavy-duty vehicles. “That means any liftgate batteries are 45 feet away from the alternator,” said Purkey, who’s now retired. “As current flows down the conductors, it results in less voltage to charge the [liftgate] batteries.”

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Low outdoor temperatures also can lessen voltage.

In response to both situations, Purkeys makes a direct liftgate charging system that boosts voltage using a DC-to-DC converter that fully charges electric liftgate batteries faster to overcome voltage drops from the tractor-to-­liftgate batteries.

“There are still people using the traditional dual pole that ties the truck and tractor together,” Purkey said. “But even though you might get the voltage up high enough to charge liftgate batteries, you never keep the truck battery in a good state of charge,” he said.

The company’s trailer auxiliary power system (TAPS) installs at the back of a trailer and charges electric pallet jacks and other AC-powered tools as well as liftgates.

“TAPS uses an inverter only when the tractor is running and converts AC to DC,” said Purkey, noting it’s compatible with every tractor and trailer.

Meanwhile, collecting power from a different source are mobile solar-power systems that can be mounted atop truck cabs and trailers.

“Solar panels as auxiliary power devices are gaining traction,” said Bill Margroum, general manager at Leyman Manufacturing. “If one cell goes out on the solar panel, the rest will still work.”

As one example, the systems made by eNow Energy are one-eighth-inch thick, aerodynamic and resistant to road salt, and permanently adhere to the truck or trailer top.

“Not only does the system keep liftgate batteries from dying, it extends the life of those batteries two to three times by maintaining an optimal charge through a charge controller,” said Guy Shaffer, eNow’s chief marketing officer.

Shaffer said one 310-watt solar panel also can be used to extend the run time of truck HVAC systems, which today tend to be electric or battery-operated instead of diesel-powered.

The company’s mobile solar systems typically cost less than $900 and might pay for themselves in six months to one year, depending on the application and amount of available sunlight, Shaffer said.

Leyman Manufacturing does not make liftgate charging systems, but it does make a power unit that monitors liftgate systems.

“If battery voltage drops, amperage goes up and that’s when you burn up motors,” Margroum said.

The power unit produces an audible alarm to alert drivers to low battery voltage, high temperature, maximum run time and maintenance needs.

“It also tracks the operation of the liftgate from the first to the very last cycle,” he said, “so it has lifetime information.”