Productivity Gets Power Boost

Jan. 1, 2005
Fast Charging Increases Battery Charge at Every Opportunity

Just think of the productivity gained and money saved if large warehouses and facilities could use one battery per lift truck and charge it without having to remove the 2,000- to 3,000-lb. behemoths. Fast charging is a recently developed battery-charging technology major companies with large electric lift-truck fleets should consider, says Brett Wood, national product development and marketing manager, Toyota Material Handling USA (Irvine, Calif.), one of the largest lift-truck manufacturers in the United States.

He says a growing number of national companies with extensive electric lift-truck fleets are realizing gains from fast-charging batteries. The systems, for example, are installed in Home Depot import distribution centers, Continental Airlines airport hubs, Nestlè USA food product warehouses and distribution centers, and manufacturing plants.

The latest company to announce it is moving to fast charging was The Ford Motor Company (Detroit) at the recent ProMat 2005 tradeshow in Chicago. Ford said it is converting its internal combustion-engine fleet of lift trucks to electric using AeroVironment's (Monrovia, Calif.) PosiCharge fast-charger system. The technology is being deployed throughout its manufacturing operations.

Ford is taking its electric-vehicle installation one step further. PosiCharge is working with I.D. Systems Inc. (Hackensack, N.J.), a supplier of wireless fleet-management products, to give Ford a custom radio-frequency identificationbased data management system that delivers real-time truck, charger, battery data and management recommendations.

Powering Up Productivity
Toyota's Wood says his team recently completed a technical comparison of the top three fast-charger manufacturers, AeroVironment's (Monrovia, Calif.) PosiCharge fast-chargers; Aker-Wade Power Technologies LLC's ( Charlottesville, Va.), UniMax and TwinMax chargers; and Edison Company's (Irvine, Calif.), Edison Minit-Charger.

The company's study looked at fast-charger benefits and potential concerns. The benefits are many. The technology saves time, reduces accidents, and frees space in warehouses and distribution centers. Batteries stay in the lift truck and are plugged into stations for charging. "

Opportunity charging" takes place during operators' lunch or break times and between shifts. Some companies place the charging stations near these areas to reduce operators' commute time, which can be as long as 10 minutes in large warehouses. Employee productivity is increased and injury avoided by not having to remove the heavy batteries from the trucks. Fast chargers improve warehouse and facility space utilization by eliminating the need for battery changing rooms and equipment.

In addition, "opportunity" 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 80% to 20% 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 80% to 20%.

Michael Matson, a product manager at GNB Industrial Power, a division of Exide Technologies, (Aurora, Ill.) that manufactures industrial batteries, says the downside of running three shifts with fast-charged batteries is that there is not enough time to equalize the batteries to remove the buildup of sulfate on the plates. Over time, the sulfate crystallizes and reduces the battery's capacity. Fast charged batteries used in three-shift operations sometimes last only two or three years, he says.

Getting Out What's Put In
Fast charging is not a technology for one-shift operations with a lift truck or two. It is too expensive for small companies to achieve a return on investment (ROI). Charging stations can start at $9,000 plus installation costs. Fast charging is really best suited for large companies, like Ford or Home Depot, that won't blink if installation of fast-chargers requires upgrading the entire electrical system in a plant, warehouse or distribution center.

Companies are already reaping the benefits of fast charging. In Tour of Lift Truck Duty, Material Handling Management, June 2004, page 28, Nestlè USA said replacing 60 conventional chargers with 11 Edison Minit-chargers shaved 15% off the costs associated with changing old batteries.

However, as the Toyota study revealed, because ROI is different among customers, it could not make a statement about ROI. Obviously, Wood points out, large lift-truck fleets get ROI gains from fewer battery purchases. One battery can cost $2,000 to $3,000. Lift trucks running multiple shifts need two or three traditional acid batteries, while trucks using fastcharging batteries generally need only one.

Monitoring is another area where fast charging technology can deliver ROI. Fast chargers are smart. The monitors give sophisticated customers good feedback about their overall operations, Wood says. Modules on the batteries monitor charging history, truck usage, and water-level. They also can adjust their charging strategy based on the battery type, electrolyte temperature, and voltage. Monitoring ensures a good charge without damaging the battery.

Things to Consider
The Toyota study discusses several costs associated with fast chargers including:

  • Charger Cost: Fast charge systems are more expensive than conventional systems. A thorough financial study needs to be completed for each application before investing in this technology.
  • Infrastructure Cost: Upgrades may need to be made to the electrical infrastructure of the building.
  • Installation Cost: Costs associated with system installation, including battery and truck modifications, and specialized service and maintenance requirements for both.
  • Reduced Battery Warranties: Battery companies typically give a five-year warranty on batteries in conventional charging applications. In fast-charge applications, the warranty is three years. "This is starting to change as companies are becoming more comfortable with the technology," Wood says. "Study your fast-charge battery warranty carefully because it may be different from traditional battery warranties," he advises. GNB Industrial's Matson says better battery warranties are based on amperage hours.

When fast charging, originally developed for use in electric cars, was commercialized 1998, no one knew if it would damage batteries. "The technology used today really doesn't damage the battery, and there is no impact to the lift truck," Toyota's Wood says.

Even though fast-charged batteries passed the five-year damage test in 2003 and some battery companies are starting to modify warranties, GNB's Matson is not completely convinced. "It is an evolving technology. No one really knows the effect on acid batteries with fast charging." The challenge, he says, is to design batteries that work in all cases.

Fast Charge Modifications to Truck and Battery

Batteries and lift trucks need simple, inexpensive modifications to be adapted to fast charging. However, the manufacturers need to make the modifications, otherwise warranties will be void.

  • Battery Modifications:
  1. Dual cabling is required for high power levels.
  2. Battery connectors with communication ports are used to send signals to the chargers.
  3. A battery monitoring device and sensors are placed on the battery to monitor temperature, voltage and water level.
  • Truck Modifications:
  1. Dual battery cables need to be routed to rear of the vehicle. The battery hood may need to be modified to allow cable routing.
  2. Connector mounting needs to be provided at the rear of the truck.
  3. A jumper cable is required to connect the battery to controller.

Source: Toyota Material Handling USA

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