Fast Chargers Power Up Lift Trucks

April 1, 2006
Fast charging lift truck batteries boosts safety and productivity.

Fast charging is quickly becoming the preferred method for recharging electric lift truck batteries in heavy-use applications. The technology saves time, reduces accidents, and frees space in warehouses and factories. The current market for the technology is hot. Fast charger providers like PosiCharge, a division of AeroVironment Inc. (Monrovia, Ca.), Edison Minit-Charger (Irvine, Ca.), and electric battery supplier EnerSys (Reading Pa.), report that the market is expanding 50% to 100% year over year.

Switching to fast charging technology is a no brainer. Lift trucks are plugged in on breaks, over lunch, during shift changes and at night. Safety and productivity are improved because less time is spent in the accident-prone task of changing 3,000-lb. batteries. Floor space is gained through the reduction or elimination of battery rooms.

The Ford Motor Company (Dearborn, Mich.) started using fast charging in a pilot study in 2000. A year ago, PosiCharge was contracted to install fast charging in all of Ford's 40 North American plants. About half of the plants are now converted.

Ford plants with fast charging are safer because lift trucks are charged in their work areas. They no longer travel a quarter mile across the plant to the centrally located battery changing room. Because it no longer needs battery rooms, Ford was able to re-cover valuable floor space and simplify some of its production runs.

Cold Not a Problem
Fast charging works in one of the coldest places in California: Dreyer's Grand Ice Cream's (Bakersfield, Calif.) regional distribution center, which includes a manufacturing plant and an attached cold-storage 105,000 sq.-ft. warehouse. Dreyer's has been using fast charging for more than a year, says Doug Bame, project manager, mainly because it wanted a safer and more efficient way of changing electric batteries. Stacy Edgar, Dreyer's warehouse manager, witnessed several serious accidents in battery changing rooms, like broken legs and ankles.

"We wanted a system that plugs in. We did not want to have to worry about taking batteries off [lift trucks] three times a day," Edgar says.

Another concern was the productivity lost to make three daily, 15-minute battery changes on each of Dreyer's 30 Linde and Crown lift trucks. After installing PosiCharge fast chargers, battery changes were reduced from 90 a day to 30 a week.

The dock, where charging takes place, is zero-degrees. The warehouse is minus 20 degrees. At first, there were a few problems with charging batteries in a zero-degree environment. However, PosiCharge corrected the problem, and now, Edgar says, "We are getting as good of a charge as we were with our old system."

Not Just for Three-Shift Operations
William M. Mazur, operations manager, The Mazel Company (Solon, Ohio), a close-out merchandise warehouse, bought his company's K&W Hawker fast charger 15 years ago, and he still uses it to charge the batteries on his fleet of Crown and Raymond lift trucks. He actually started to use battery recharges 25-years-ago when he worked at Revco, a northeast regional drug store chain that was later purchased by CVS.

When his Raymond swing reach truck is opportunity charged throughout the day, it has enough power for the entire shift. Mazel's warehouse runs one shift a day. Fast charging is usually recommended for two or three-shift facilities because of equipment cost. However, Mazur said his company achieved its ROI on the technology in about three years because he saved money on batteries. Typical 36V batteries cost $4,000 to $5,000.

Fast charging returns energy to the batteries at high power levels, typically 10 to 20 kilowatts per truck. This power level maintains the battery within the 20% to 80% state of charge window. In two-shift operations, batteries are able to return to 100% charge after the second shift. In three-shift operations, chargers have to return the same amount of energy that the trucks are using to maintain a state of charge between 20% to 80%.

Fast charging can also extend battery life. Mazur says his fast-charged batteries have an average life of 10 years; he is still using an 11-year-old battery. Batteries can last longer because fast charging does not heat batteries as much as conventional charging does.

The Learning Curve
Fast chargers have high-speed micro-processors that can be programmed to automate battery maintenance. The chargers automatically identify batteries that need to be charged and determine the best charge rate and power conditions. They can also produce reports that track a variety of battery metrics.

Philip Smiley, assistant material manager, Lear Corp. (Arlington, Texas), has been using fast chargers with EnerSys batteries for more than a year. "They are working well," he says. "Fast chargers are good for facilities that have space constraints."

Lear placed its fast chargers between the dock doors in its 90,000 sq.-ft. Arlington facility. The only problem he has experienced with fast charging was the learning curve—training workers to plug-in during breaks and lunches. He runs two eleven-hour shifts with 14 Toyota lift trucks.

At his just-in-time facility, lift trucks are charged after unloading at receiving. The lift trucks are between 75 to 80% utilized. Gages on Lear's lift trucks beep when the batteries power level reaches a preset level. Drivers plug their trucks in and watch the percentage of charge on the battery rise. Smiley monitors battery activities, when and how long the battery was plugged in and the temperature of the battery from start to finish.

"It is good data from a management standpoint," Smiley says. "It is a good tool for managing the operators. You know who is plugging them in and when."

Another benefit of running a fast-charged all-electric fleet is a cleaner and quieter work environment. Lear had a propane-powered fleet before switching to electric. "Since we started using electric-powered lift trucks, there have been fewer complaints about the air quality and noise in the facility," Smiley says. Additionally, there is a reduced risk of dropping propane tanks and hurting people. Smiley does report that the cost of the electricity needed to charge his fleet is equal to the cost of propane he once used.

Total Switch to Electric
"Our fleet of propane lift trucks was old and out-dated, and internal air quality was an issue." says Bill Woyshner, divisional environmental and security manager, for Shaw Diversified Services' operation in Santa Fe Springs, Calif. Plant managers decided to convert to electric lift trucks inside the plant.

They soon discovered that OSHA and city regulations would require the construction of a battery room if they selected conventional battery charging and exchanging technology. For this plant, that meant an addition to the building with outside access.

"It would have been a more difficult decision to convert to electric," Woyshner says, "had we not investigated the use of fast charging instead."

During this process, managers at a sister Shaw Plant in Calhoun, Ga., conducted a detailed evaluation of fast charge providers. Because the shift schedule was very demanding with three shifts per day, they needed to insure the fast charging system could meet their needs. Following that evaluation, managers at the Santa Fe plant arranged for a local demonstration of a fast charge system and liked what they saw.

The company converted to Edison Minit-Charger fast chargers in late 2005. The lift trucks and batteries were delivered "fast charge ready" and it was an "effortless conversion," Woyshner says. "The drivers have had no problems with quick charge and we have had no issues of batteries not being charged properly."

Ford Motor Company is converting to fast charging in all of its North American plants.

PosiCharge fast charger.

Fast Charging Benefits

  • Longer battery life.
  • Less battery maintenance.
  • Compatible with existing batteries.
  • Charging of multiple voltage batteries (24V, 36V, 48V) with the same charger.
  • No requirements for battery cool-down time.
  • Automatically detects the battery's level of discharge and will only supply the amount of power needed to restore it to full charge.
  • Eliminates the need for large battery charging rooms.

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