This case history about William Morrison Supermarkets comes courtesy of Philadelphia Scientific . It has been selected and edited by the MHM editorial staff for clarity, content and style.
As the American economy continues to sag, businesses are looking to squeeze savings out of their operations. Across the pond in the U.K., there’s one company that has cut costs in an unlikely place: the lift truck battery-changing room.
William Morrison Supermarkets is the fourth-largest supermarket chain in the U.K. Founded in 1899, the company includes more than 370 supermarkets. William Morrison operates distribution centers throughout the U.K., including a frozen-food distribution center in Wakefield, about 30 miles northeast of Manchester.
The Wakefield facility stores fresh produce, bread, soft drinks and wine. Approximately 100 lift trucks are used within the facility. About 65 to 70 of the trucks are order pickers, which each use 24-volt, 465 ampere-hour batteries. About 25 are reach trucks using 48-volt, 750 ampere-hour batteries. The remainder are pallet trucks using 24-volt, 345 ampere-hour batteries.
A few years ago, the distribution center began experiencing problems with shortened battery life. Lift truck drivers discovered some of the batteries they were using were only getting about six hours of service per charge versus the eight hours they expected, requiring that the drivers change batteries more frequently.
The problem appeared to be limited to the order pickers, leading to the theory that the problem was related to the function of the truck. Several attempts were made to solve the problem, including separating the order picker batteries into two pools–one made up of batteries used in the cold section, the other comprising batteries used in ambient temperatures. This however, made the problem worse.
Duncan Jones, managing director of Philadelphia Scientific Europe, a manufacturer of battery components, accessories and tools, notes that, while the solution to a battery performance problem typically is not complex, identifying the problem isn’t always easy. “Most battery room managers aren’t taking advantage of today’s battery management tools–tools that can help prevent battery problems or quickly identify specific problems when they occur,” he says.
Frustrated at not being able to identify the source of the problem and realizing that the undercharged batteries were costing time and money, the battery supplier, Chloride Motive Power, investigated an intelligent battery organizing system (iBOS) from Philadelphia Scientific (Montgomeryville, Pa.).
Battery organizing systems act as battery sequencers for battery changing rooms, determining which battery has had the longest cooling time since charging. It organizes the battery-changing operation in real time to ensure that all batteries are used in strict rotation, preventing battery abuse and related problems.
According to Harold Vanasse, vice president of sales and marketing for Philadelphia Scientific’s U.S. operation, “When lift truck drivers enter a battery room to get a replacement, they typically take the most convenient one. And, site tests have shown that, if battery selection is left to a truck operator, 30% of a pool of batteries will be underutilized, and 20% will be overused. Over time, this leads to uneven usage of batteries with expensive consequences, such as diminished capacity, uneven wear and premature battery failure. Other assets are wasted, too, because the less-convenient batteries go unused. An intelligent battery organizing system eliminates these battery-room problems.”
The iBOS collects charger data through electronic monitors called sentinels. The sentinels send this information to the organizing system’s central brain, called a controller. The controller processes the data and sends it to a display (either a scrolling LED screen or flat-touch screen), which informs the lift truck operator which battery to take.
The battery-room activity data collected by the controller can be analyzed and used to produce management reports detailing availability, mispicks and utilization. Availability reports provide daily maximum and minimum battery utilization information, which can be used to determine if there are too many or too few batteries in the pool. Mispick reports display the day, date and time of each mispick, helping to identify the different types of mispicks and allowing for efficient supervisory attention. Utilization reports detail utilization by charger, identify uneven charger usage and pinpoint equipment problems with chargers, roller beds or cables.
After installing the iBOS system in the battery room and allowing it to run for several days, managers at the Wakefield facility noticed that the iBOS reports began highlighting problems. The site efficiency reports showed that drivers were running out of batteries every day on both the order pickers and the reach trucks, while the diagnostics reports highlighted chargers that were not functioning. According to the reports, nine chargers and/or batteries had problems that had not been previously recognized. A Chloride Motive Power engineer discovered that some of the chargers had been stalling during the charging process and had stopped charging when the battery was at about 50% capacity. When a driver saw that the battery apparently was still charging, he went on to the next battery, leaving a battery connected to a faulty charger.
The faulty chargers were quickly repaired, and after a few days, another diagnostics report was generated. With all the chargers now functioning correctly, it became apparent that the drivers were still running out of reach-truck batteries on a daily basis. The issue was resolved by adding two new batteries to the reach-truck pool.
The order-picker batteries were still divided into two pools, but the iBOS reports revealed that a minimum number of batteries were available at different times. Managers theorized that putting the two pools back together would result in a higher number of available batteries. When both pools were combined, data indicated that the pool had plenty of spare batteries, and the number available was more consistent throughout the day.
There are a number of ways to calculate the cost savings of better battery management at the Wakefield facility: savings due to improved battery maintenance; improved driver productivity; and battery purchase avoidance. “Good battery management and maintenance can result in the need to purchase batteries approximately 20% less often,” says Jones. “At Wakefield, that represents a savings of about $100,000.
“A battery organizing system improves driver efficiency too,” he continues. “At Wakefield, we calculated that changing batteries every six hours rather than every eight hours results in 22 wasted minutes per truck per day. With 100 trucks in service, and at a wage of $20 per hour, this represents $292,000 in savings in one year.”
Once the real problem was identified at the Wakefield center, it became apparent that the batteries the facility was planning on purchasing were not required, which saved an additional $40,000. “That’s a total savings of $432,000,” Jones says.
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