You can change it or you can charge it.
When an electric lift truck's battery begins to lose its juice, DCs deal with it in one of two ways: They either remove the drained battery and replace it with a fresh one or they send the lift truck over to a high-voltage charger for a quick recharge while the battery remains in the truck. Whether a given DC chooses the traditional battery exchange method or the newer "fast charging" option depends on a number of factors, including the number of vehicles in service, time available for charging, size of the loads carried, and space available for power management.
In the not-too-distant future, there may be a third choice. Looming on the horizon is yet another power technology. Hydrogen fuel cells, though still very much in their infancy, may someday find practical applications in warehouses. With fuel cells, there are no batteries to be charged; the fuel cells would simply be refilled with hydrogen, similar to fueling a car with gasoline. But that day still appears to be a ways off. Fuel cell developers have yet to produce fuel cells that provide enough power at a cost competitive with established systems.
Time for a change
How the future of power management shakes out is still an open question. But in the meantime, both vendors of battery changing systems and fast-charging systems continue to introduce new options.
Take the traditional battery changing systems, for example. These systems continue to grow in size and sophistication. Labor costs play a big part in this. Companies looking to reduce labor costs can opt for fully automated systems for swapping out batteries, rather than paying an employee for that function. Many of these systems are multi-level and can hold hundreds of batteries. Automated cranes provide the muscle to move the batteries around.
"Automation is certainly a trend we see, eliminating the need for a battery operating person," says Dan Dwyer, vice president and general manager of Sackett Systems, a company that makes battery changing equipment.
Another selling point for automated battery changing systems is safety. Batteries are very heavy and facilities may choose automation to reduce the risk of injuries.
Speeds are also increasing. "The value in a system is having the right battery available when the truck enters the changing area," says Dwyer. This takes coordination between the truck and exchange system so that the vehicle can be serviced as fast as possible. A good system today can change a battery in less than a minute.
Customers also have several options when it comes to the battery changing system's design and layout. For example, DCs with space limitations can install multi-tiered systems that feature rows of chargers stacked one on top of the other. If space is not a problem, however, single-tier systems that align batteries and chargers in long rows at floor level provide a less costly and faster alternative (there's no wait while the battery is retrieved from an upper level). In the end, says John Pratt, owner of battery handling systems maker Multi-Shifter, the decision comes down to this: "What is more important to you, saving space or gaining productivity?"
The success of any system, though, hinges on whether it can deliver a battery that can last an entire eight-hour shift. This is where good battery management comes into play.
"Battery management systems are helping customers identify battery usage to properly forecast replacement batteries," notes Martin Huber, president and CEO of BHS (Battery Handling Systems).
"Software integration has become a huge part of systems today," adds Jim Lane, vice president of sales for Materials Transportation Co. (MTC). "We used to sell just changers; now we sell them with battery management systems."
Using measurement tools and analytical software, battery management systems optimize battery usage and determine when batteries have reached the point in their lives when it is no longer economical to recharge them. "The goal is not to keep a battery 10 years," says Lane. "Companies need to scrap batteries that are poor performers."
Make it fast
Like the battery exchange business, the fast-charging segment has matured in recent years as the technology behind it has improved. The cost of fast charging has also dropped, which has accelerated its adoption. Chargers that cost $20,000 about eight years ago now can be had for half that price.Manufacturers of these systems predict that costs will continue to drop as technology improves and chargers become smaller.
Because these systems have regular contact with the batteries and their vehicles during charging times, they are able to easily collect charging data to help manage battery performance—so much so that Larry Hayashigawa, director of product management for PosiCharge, likes to refer to fast charging as "intelligent charging." Some of his company's charging systems, for example, include data collection units that are placed on customers' lift trucks to track battery and vehicle performance. Whenever the vehicle is connected to the fast charger, operating data are automatically downloaded to a server, providing technicians with at-a-glance information such as how many amperes went into the battery at its last charge, how much was discharged during the last shift and when the battery was last watered. Managers can then use the data to manage their charging systems or to determine when it's time to replace an aging battery.
While 36-volt batteries continue to be the norm for fast charging, some higher voltage systems, such as 80 volts, are growing in use. Eighty-volt batteries produce less heat than lower voltage cells and can be more efficient. Of course, this requires a lift truck that can operate at 80 volts. Several truck manufacturers, especially those based in Europe, produce such vehicles.
"Eighty-volt is well suited for powering vehicles that have to carry heavy loads," notes Hayashigawa. He says that with increasing mandates to lower vehicle emissions, the 80-volt batteries are being used to power new heavy-duty trucks that customers are buying to replace their fleet of LP vehicles.
Experiments are also being done on using higher voltages to reduce charging times.
"We continue to work with battery packs as high as 312 volts," says Peter Michalski, vice president of Edison Minit-Charger, a manufacturer of fast-charging systems. He says that using the higher voltages can drastically reduce charging times, though at a higher cost of electricity. "A 1,000 ampere battery can be charged at 312 volts in only 10 minutes," he notes.
Cold storage applications represent another frontier for fast charging. Users are reporting good results using fast charging for these applications, where freezing temperatures often zap batteries of their performance. Another potential use for fast charging is in the area of "opportunity charging." Edison's Michalski says that some 25 to 30 percent of lift trucks using conventional batteries never have them exchanged. Instead, users simply charge the battery while it remains in the truck. Unfortunately, these batteries often do not receive a full charge, as the vehicles are needed before they can be adequately topped off. This tends to diminish long-term battery life. Michalski says that fast chargers could be used for these applications, as they provide a better overall charge than the spotty practice of hooking up for short periods to conventional chargers.
As for where the next innovations in fast charging will come from, Michalski points to battery design. "One thing that has yet to happen is battery manufacturers' embracing fast charging to the point where batteries are designed from a clean sheet of paper for fast charging, rather than just modifying conventional batteries," he observes.
Michalski says a dedicated fast-charging battery should provide longer life. He also notes that future batteries may include carbon-based grids, instead of lead, which could improve durability and reduce the amount of heat generated from fast charging.
Best of both worlds
Even with efficient fast-charging systems, batteries still need to receive full charges every once in a while. "Batteries have to charge a certain amount of time to come up to full level," explains Pratt.
For that reason, he says, some customers may find a hybrid solution is best suited to their needs—one that may include fast charging for some vehicles and, at minimum, a single-level system that allows some battery rotation and emergency changes. Even with fast charging, batteries eventually wear out, which means a DC still needs some way to replace a battery at the end of its life cycle. These small hybrid systems using the best of both technologies may provide a good alternative.
Whatever system a company chooses today or in the future—changing, fast charging, a hybrid mix or some type of fuel cells—the accountant's bottom line will still be the major factor in the company's decision how to handle its batteries. "It's all about upfront capital costs and then cost per kilowatt," acknowledges Lane.
In this market, it seems, money literally is power.
