Fleets of more than 50 lift trucks in multiple-shift operations or those with long single shifts are prime candidates for “opportunity” or fast-charge solutions.
The difference between fast and opportunity has to do with charge rates and charging practices, but the common theme is a migration away from battery changes. This can lead to the elimination of the battery room, notorious for its costs, clumsiness and frequent mismanagement.
But although zero battery change solutions can boost uptime, reduce battery inventory and simplify cost tracking, the technologies have been criticized for creating unrealistic expectations of operators more concerned with getting the job done than adhering to strict charge routines.
“Proper enforcement was rare,” says Steve Spaar, director of marketing for EnerSys. “One of the big keys to success is to get operators accustomed to plugging it in every time. If you miss two or three of those 15-minute windows, the battery state of charge goes down. Before long, the battery is dead and the lift truck is stranded. This used to be the biggest issue.”
Spaar suggests that advances in the design of solutions, hardware and the processes supporting them can alleviate the “house of cards” effect with which some early adopters struggled. “Before implementation, when sizing a battery system, it is now common to leave a little extra wiggle room so if an operator misses a couple plug-ins, you can compensate,” Spaar says. “The next challenge is the placement of charging stations.
In brownfield applications, if a battery room is not reclaimed for other uses it is common to locate a bay of chargers in the same footprint. However, this does not address the impact of traveling to the central location for a charge. “In a one million-square-foot facility, it can take 10 minutes just to get to the charger,” Spaar says. “The optimal situation is to put chargers where the work is done, but that’s not always possible.”
It is not inexpensive to install a 60-amp service line to a strategically located charger in the middle of the warehouse, Spaar says, assuming the space needed to park a lift truck is available in the first place. A parking and charging bay might instead be located near a break room where operators and equipment congregate anyway. Another solution is to use existing space between doors at the dock, where non-productive space can be used to keep equipment charged and ready for loading and unloading.
“I recommend starting with a feasibility study and basic data recorder,” Spaar says. “Modeling software can help identify whether fast charging or opportunity charging could work, and it can help set up a fleet for a successful transition to zero battery changes.”
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