As ground service providers seek ways to remain efficient on the ramp while being conscious of their environmental impact, lithium ion (Li-ion) battery technology is becoming an appealing power supply option for ground support equipment (GSE).
The first commercially viable Li-ion batteries were introduced approximately 10 years ago. However, their small size and large expense prevented them from being a viable option.
According to Todd Allen, president of Allen Energy – the North American distributor for Colibri Energy and EnerSys batteries, Colibri introduced a high-density lithium polymer battery to the GSE market seven years ago and has recorded more than 10,000 operating hours in a variety of environments. Lithium chemistries continue to improve, he says, adding the batteries’ performance in GSE will continue to progress as well.
“The short-term improvements will be increasing power density, which will directly drive prices down,” he explains. “It’s in the realm of possibility that you could have a Li-ion battery that lasts twice as long as a lead acid battery and requires no maintenance, all at the same price you pay for lead acid today.”
The chemical make-up of Li-ion batteries differ from their counterparts. Simply put, the active metal in lithium batteries is lithium, while the active materials of lead acid batteries are lead and lead dioxide, explains Brian Lesch, sales manager at Averest – the distributor of Flux Power and Deka batteries.
“It’s still a battery. It still charges and discharges as the user uses the vehicle,” Lesch says. “They’re just different chemistries.”
“Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest energy density for weight,” adds Anthony Cooper, general manager of motive power at Green Cubes Technology – a manufacturer of Li-ion batteries.
Li-ion units benefit from a battery management system (BMS), a device that helps monitor and control battery functions.
“It’s almost like a little computer,” Lesch says. “It monitors temperatures, voltages, cell health – the health of the battery.”
The BMS monitors the cells to prevent them from over- or under-charging and allows the customer to collect valuable data to track their production and efficiency, explains Cooper.
“Li-ion batteries require no maintenance because of the chemistry, engineering and manufacturing,” he notes.
As a maintenance-free battery, Li-ion units do not require watering the same way lead acid batteries do.
Lead acid batteries are filled with electrolyte – a mixture of water and sulfuric acid. When the battery is used and charged, the water evaporates over time. To maintain the battery, users have to add water to the cells.
“As that battery ages, the more often you need to add water to those cells,” Lesch says. “For example, a bag tractor battery is an 80-volt battery – so that has 40 cells in it. Each one of those cells will need to be individually watered.”
“A lead acid battery always produces hydrogen and oxygen during the charging process. Some advanced lead acid batteries recombine the gasses back into water before they escape the battery,” Allen adds.
Often, especially in warm places where water may evaporate more quickly, one person is assigned to watering batteries all the time.
“Along with that watering, you run the risk of spillage – spilling some of that acid out of the battery,” Lesch points out. “That’s not great for the environment.”
Li-ion batteries do not require other routine maintenance such as equalization as the onboard BMS does this automatically.
“When everything is working perfectly, a lithium battery is truly a maintenance-free battery. Our users should never have to get inside that battery for anything,” Lesch says.
Like other electric vehicles, Li-ion battery-powered GSE has no environmental impact.
“There’s no emissions,” Lesch says, noting airports across the U.S. and around the globe have initiatives to go green with grants and other funding available for these conversions.
“If they’re able to put in the charging infrastructure, (airports) want them to swap out their diesel and fossil fuel vehicles for electric,” Lesch says.
In addition to going green, Li-ion offers extended life. According to Allen, the lifespan of Li-ion GSE applications is still unknown. However, original batteries are still running efficiently.
“I think 10 years while maintaining most of the original capacity is a reasonable expectation. There’s no reason a battery can’t last 15 years or more in cooler or lighter duty environments,” he says. “The batteries have built in controls so that you can’t abuse them.”
Officials at Averest have been testing their original Li-ion-powered vehicle every six months over the last four and a half years. That battery is still at 96.5 percent capacity.
“We fully expect, at a minimum, 10- to 12-year lifespans – if not more,” Lesch says. “We expect that battery to last the first life of the tractor.”
Li-ion batteries can also be an attractive option for GSE applications because the battery communicates with the vehicle via CAN-BUS – rather than being entirely voltage driven.
“It doesn’t experience the voltage drop of lead acid batteries,” points out Rob Laster, general manager at Averest. “To maintain the power that you need because of voltage drops, with lead acid you have to actually kick up the amperage to remain at the same power level. You don’t have to do that with lithium. So, it could possibly be easier on the contactors and the other internal components of the tractors, themselves.”
“The lack of voltage drop is a huge, huge benefit for lithium – especially when you’re talking about a container loader that requires a significant amperage draw, and also with a pushback,” Lesch adds.
Li-ion batteries do not require equalization either, as cell balancing technology has advanced and is integrated into the BMS.
“That continues to evolve to the point where we’re looking at quantum cell balancing, and new technologies, so that the health of those cells are maintained constantly,” Laster says.
While upfront costs for Li-ion batteries may come with some sticker shock, the technology offers a lower total cost of ownership (TCO) and a speedy return on investment (ROI).
“Dramatic cost reduction will happen naturally with advancements in Li-ion chemistry in the next couple of years,” Allen says.
Disposal and recycling of Li-ion currently lags behind lead acid but is catching up.
Green Cubes Technology offers a recycling program to help combat this issue.
“Depending on the end customer usage, the recovered Li-ion batteries may have significant energy remaining,” Cooper says. “While the energy is too low for high usage ground support applications, it’s well suited for applications such as Solar Energy Storage. After the second life of the battery, many other parts can be recycled for reuse.”
Extinguishing Risk Concerns
Some consumer products using variations of lithium technology have caused concern about the risk of fire. However, the batteries used in GSE do not come with those risks.
“The chemistry that we use in these batteries is lithium ferro phosphate. It’s the least energy dense of the lithium technologies that you see out there,” Laster points out. “For most people, when they think of lithium, they think of what’s in the hoverboards, what’s in their phones. Those are extremely small and provide a lot of energy.”
Batteries used in GSE are much lower on the density scale for lithium.
“Fire, while it’s not impossible, it’s not any higher risk than lead acid batteries or fuel for internal combustion engines,” Laster says.
“Li-ion is inherently an unstable chemistry,” Allen notes. “However, quality manufacturers can build in safety to their designs to provide an extremely safe product with no risk of fires.”
Li-ion batteries in GSE have a thermal runaway of 500 degrees. And, what’s more, the batteries are fused.
If there is ever an issue, the BMS will shut down the battery to prevent continued charging or discharging.
“There is a very small possibility that a Li-ion battery can have a chemical reaction, which causes white smoke to emit from the battery,” Cooper says, adding Li-ion batteries do not have the potential for gas buildup that can ignite nor acid that can spill, erode and cause bodily harm.
With a safer chemistry, users will lose some energy density.
“We’re sacrificing a little bit of run-time for safety. From a GSE standpoint, that’s fine,” Lesch says.
Li-ion batteries charge more efficiently and do not generate excess heat during the charging process. The battery chemistry can also hold its voltage during discharge better than other options.
“Li-ion batteries can usually use the same chargers as lead acid, there are a few cases where a new charger would be required, but this is not very often,” says Cooper. “Li-ion chemistry allows for 98 percent or higher charging efficiency.”
“Older conventional chargers shouldn’t be used. But all the latest ‘smart’ charging technology is capable of charging li-ion,” Allen says, adding EnerSys, Power Designers, PosiCharge and several other brands of chargers are available.
Opportunity charging is also possible, and often promoted, so ground handlers and other users do not have to wait for the battery to be depleted before placing it on the charger.
“The ideal location is to put these chargers near breakrooms because it encourages these users to plug-in, more so than not,” Lesch says.
Because of its small footprint, a Li-ion battery can often be utilized as a power source for ground support equipment with minimal effort.
“Since the Li-ion batteries are similar in size to the lead acid batteries, they can be easily dropped into existing equipment,” says Rob Lamb, vice president of sales and marketing at Charlatte America – a manufacturer of tractors and other GSE. “There was some concern at first by the industry that the lighter weight of the battery would negatively affect the tractive effort of the vehicles, but our testing has shown that the impact on our vehicle’s drawbar performance has been quite minimal.”
According to Lamb, Charlatte’s engineers have found that any piece of equipment that can be powered by a flooded lead acid battery can also be powered by Li-ion.
Cooper notes a Li-ion conversion is an easy process that simply requires some information about the make and model of GSE, such as voltage, amperage and minimum weight.
So, while the battery can be put into position with little trouble, the work primarily comes from getting the battery to read the state-of-charge and know how to shut down when it needs to.
“The work has to be done to get the battery to properly communicate with the tractor,” Lesch explains.
Those two components need to communicate with each other to optimize usability.
Li-ion batteries can be installed by the OEM or battery supplier. While retrofits are possible, often Li-ion powered vehicles are built new.
“It makes sense to have the OEM install it at the factory and make sure the system is operating properly,” Allen says.
Li-ion batteries are beginning to find traction in the industry, powering GSE vehicles from Charlatte, TLD, Textron GSE, Toyota, MULAG, Trepel and Still, among others.
Charlatte vehicles powered by Li-ion are in operation at airports in Salt Lake City, Minneapolis, Boston, Seattle and Atlanta and several locations in the Middle East.
“Initially, we found that customers were intrigued by the benefits of Li-ion batteries but discovered their upfront cost to be prohibitive to making that switch from lead acid,” Lamb says. “Recently, however, we have been experiencing increased interest from more budget-minded handlers who are now recognizing that those advantages combined over the life of the GSE make Li-ion an economically viable decision."