Despite the cost and environmental advantages of battery-powered ground support equipment, most baggage tractors and belt loaders in operation still rely on diesel power. Southwest Airlines, however, is moving quickly in the other direction. Living up to the “overall commitment to efficiency and the planet” cited in the company’s “triple bottom line approach,” the Dallas-based carrier is converting its fleet of baggage tractors and belt loaders from diesel power toward greener, more efficient electric-powered solutions.
Reflecting that initiative, Southwest Airlines recently embarked on an 18-month, multi-city trial of NexSys batteries from EnerSys. Featuring Thin Plate Pure Lead (TPPL) technology, NexSys batteries offered Southwest Airlines an option for going electric, but one without the drawbacks of flooded lead acid batteries.
In many airports, Southwest Airlines had already converted from Internal Combustion Engine (ICE)-powered baggage tractors and belt loaders to those powered by environmentally friendly flooded lead acid batteries. While these conventional flooded batteries provide inherent advantages over ICE options, they are not without limitations of their own.
Flooded lead acid batteries require watering at regular intervals – a maintenance-intensive task that’s difficult to execute on even the best-run ramps. When many dozens of ground support equipment (GSE) vehicles are spread out over several acres, watering their batteries frequently enough can be quite a challenge. Unfortunately, under-watering or over-watering flooded lead acid batteries ultimately reduces their performance and cycle life.
Overwatering flooded lead acid batteries can lead to problems during charging. That’s because ground crews won’t know if a battery has been over-watered until charging begins, at which time the excess water will flow out of the battery. As most GSE vehicles undergo charging on the ramp, such spills can be a major headache for ground crews since airline and airport environmental departments must be notified. Charging under-watered flooded lead acid batteries can also present problems, as under-watered batteries can overheat during charging.
Southwest Airlines was intrigued by these benefits, but equally impressed with a key advantage of NexSys batteries – their fast-charge capabilities enabled by TPPL technology. The positive and negative plates in the batteries are low impedance, highly corrosion-resistant thin plate grids manufactured from 99 percent pure lead. Their 99 percent pure lead plates also allow NexSys batteries to be fully charged in less than half the time that flooded or gel lead acid batteries require. Ideal for opportunity charging, the batteries offer ground support crews the added flexibility to charge them during downtime between flights – with no long equalization charging required. The 99 percent purity level of the plates also allows the NexSys batteries to deliver high-energy throughput and up to three times the battery capacity per 24 hours versus flooded lead acid batteries.
The fast and opportunity charging capabilities sounded promising, but Southwest Airlines management had initial concerns about charging compatibility – the NexSys ® batteries would have to work with chargers that were not from EnerSys. Todd Allen, owner of Allen Energy and the distributor working to supply the carrier with the TPPL batteries, assured Southwest Airlines management that they would. “Southwest was already using the latest generation of fast chargers,” Allen explains, “so charging incompatibility was not going to be an issue.”
The TPPL construction promised another key advantage for GSE usage – much better performance in low temperatures. That’s because flooded lead acid batteries and gel batteries alike can lose up to half of their capacity in cold weather environments. Convinced that the NexSys batteries would be well worth a try, Southwest Airlines gave the go-ahead for an extended test run.
The trial began in early 2014, and took place simultaneously at Phoenix, Dallas and Los Angeles International Airports. EnerSys outfitted a fleet of electric baggage tractors and belt loaders with 72-volt NexSys TPPL batteries. A wireless battery monitoring and data collection system was also installed on each vehicle to record a range of battery operating information, including voltage levels and depth of discharge.
“We are in the process of converting 60 diesel bag tractors at the Phoenix Sky Harbor International Airport and have installed NexSys batteries at Chicago Midway, Dallas/Fort Worth, Los Angeles, San Francisco and several other airports,” explains Larry Laney, Southwest Airlines director of maintenance. “The TPPL technology at the heart of these batteries is helping us facilitate our move away from diesel power, and we expect that it will help us save money in the process.”
EnerSys, the global leader in stored energy solutions for industrial applications, manufactures and distributes reserve power and motive power batteries, battery chargers, power equipment, battery accessories and outdoor equipment enclosure solutions to customers worldwide. Motive power batteries and chargers are utilized in electric forklift trucks and other commercial electric powered vehicles. Reserve power batteries are used in the telecommunication and utility industries, uninterruptible power supplies, and numerous applications requiring stored energy solutions including medical, aerospace and defense systems. Outdoor equipment enclosure products are utilized in the telecommunication, cable, utility and transportation industries, and by government and defense customers. The company also provides aftermarket and customer support services to its customers from over 100 countries through its sales and manufacturing locations around the world.