30 May 2008
Debenhams specified a complete power management solution from EnerSys for the warehouse trucks at its new distribution centre in Peterborough. The installation includes Hawker batteries for a range of warehouse trucks and incorporates advanced "call forward", monitoring, management and handling systems that are designed to maximise the performance of the fleet over busy extended shifts and help ensure a long service life for the power sources.
"We selected EnerSys after assessing a number of potential suppliers on their ability to design the solution we needed, the timescales for implementation, and previous business satisfaction as well as cost," says Jim Bezzano, Central Operations Manager at Spectrum, the retailer's logistics provider. "We're very pleased with the complete package."
Debenhams is the largest department store retailer in the UK. The new distribution centre was commissioned when the company identified that its existing supply chain infrastructure was no longer adequate to support the growing business. The site, which is operated by DHL Exel Supply Chain and is dedicated to flat storage items such as house wares, has a 726,000ft2 footprint but with an additional 540,000ft2 of storage on mezzanines in its three main chambers providing extensive capacity for growth.
The company specified an initial fleet of warehouse trucks including eight reach trucks, seven man-rising order pickers, sixteen ride-on pallet trucks and five low-level order pickers. Batteries were selected under a separate contract by competitive tender from a shortlist of preferred suppliers including EnerSys. The overall requirement was for a solution that included batteries, charge and change facilities, handling systems, and advanced monitoring and management capabilities. The objective was to ensure the optimum use of the power sources over an extended contract in this demanding and busy environment.
Enersys supplied its high-performance Hawker Perfect Plus batteries which offer extended work cycles between charges. Charging is achieved by Hawker Powertech high frequency chargers, which offer outstanding energy efficiency - as much as 20 per cent higher than traditional 50 Hz chargers. Powertech automatically detects the battery's level of discharge and will supply only the amount of power needed – and no more - to restore full charge. This means less mains power is required to charge a battery, leading to significant savings in electricity costs.
The Powertech charger is also very versatile. It will automatically accommodate batteries of different capacities, and is easily programmable for different battery technologies. All the batteries were supplied with Hawker's Aquamatic single point filling system for topping up. As part of its best-practice philosophy Debenhams specified air extraction systems which vent gases produced during charging safely to the outside of the building. It also asked for a shower at the side of the charging area as a health and safety precaution.
Project engineers from Enersys worked with Debenhams and the lift truck supplier to design, configure and install the charge and change area. The facility was commissioned in a short timeframe to meet Debenhams' schedule for opening the distribution centre. The opening date had been brought forward for operational reasons and Enersys supplied temporary inductive power transfer "bus bar" rails for charging the larger lift trucks while the new system was being installed.
The distribution centre has been built to meet projected growth over the next decade and Debenhams was keen to ensure that its battery facilities would be expandable and flexible to meet evolving requirements. One of the early decisions was the choice between single or double tiered battery storage. A double tiered configuration, with some batteries stored on racks above the others, offered the prospect of a smaller installation but would have meant additional battery handling operations. A single tier was simpler but took up more space.
"We went for the single tier option but with plenty of spare space for additional batteries," says Jim Bezzano.
The original assessment had called for 1.4 batteries per truck but Debenhams decided to take a cautious approach and specify two units for each. This additional capacity will be used to provide power for Short Term rental trucks brought into the warehouse to cope with the highly volatile seasonal peaks. This will ensure the Short Term temporary trucks have the same high-performance batteries with all the advantages of advanced management as the permanent fleet. As the fleet grows the truck-to-battery ratio should move closer to the original specification without compromising overall fleet performance and avoiding the need to buy extra batteries.
Debenhams was keen to take advantage of the latest battery management technologies to ensure the best possible performance from its investment. Enersys supplied its state of the art management system which works in conjunction with the "intelligent" diagnostic software in the power sources to oversee every aspect of battery utilisation. Batteries are allocated in strict rotation which means that the best available unit – the one with the most charge - is always used thus overcoming the potential problem of operators simply taking the nearest available battery, regardless of its true state of charge. Battery utilisation is spread more evenly between all units so that none gets heavier usage than the others. The service life of the batteries is prolonged and the risk of unexpected maintenance issues is reduced.
The lift trucks have been configured so that a battery change is required whenever it reaches a 30 per cent charge threshold. This leaves enough energy for a return to the charge for a replacement battery without the risk of a truck becoming stranded at a remote point in this large site. Drivers are responsible for changing their own batteries and have been trained to complete the task safely and quickly. As they approach the changing point a large overhead display indicates which battery should be used and where it can be found. The display provides information on all of the available batteries but the management system stipulates the one with the most charge should be used, to ensure the correct rotation, and sounds an alarm if the driver tries to take the wrong one.
"It's very visual for drivers and they can see very quickly which battery to use," says Ivor Knighton, the site's Engineering Manager.
Batteries are arranged in zones, for each type of lift truck, in two rows alongside a central aisle. Changing is accomplished using Hawker's ProSeries BBL semi-automated change cart, an electric powered trolley known as the "bull" which runs rail guided between the battery locations and the changing station. The device's platform accommodates two batteries which allows it to collect a fresh unit from a charging position and swap it with the depleted unit from the lift truck in a single duty cycle. The bull's extending electro-magnetic arm and powered roller bed work in combination ensure the smooth transfer of batteries. The whole process is a simple and quick one-man task that avoids the need for manual handling to help users to comply with health and safety regulations. Enersys also supplied one of its simpler ProSeries Tugger battery handling trolleys in case of any problems with the main system.
"The bull system has been very reliable," says Ivor Knighton. "The Tugger is there for emergencies but the only time we've used it was during the initial training."
Another major benefit of the battery management system is the performance information it provides. This includes information on the number of hours and how many times a battery has been used, charge rates, operator efficiency, hours used by truck and more. In this way Debenhams can build a profile of battery utilisation across the fleet to identify and address performance issues. For example, anomalous information about a specific battery or truck could highlight something that might otherwise go un-noticed. Debenhams has a much clearer picture of asset utilisation which can be used to make effective business decisions.
"The management system is great for getting the most out of the batteries," says Jim Bezzano. "If we have a problem we know about it and have the information to hand. It helps ensure we get the proper rotation and best possible lifecycle."
As part of its service commitment Enersys has a comprehensive support package which includes regular visits to check the batteries and other parts of the system. The company also provides a remote monitoring and diagnostic facility which allows it to download information from Debenhams' system to assess battery usage and identify any areas of concern. Reports are shared with Debenhams and the truck supplier to help all parties plan appropriately to ensure overall battery life and performance is maximised.
Hawker is the widely-recognised Motive Power brand of EnerSys, a leading supplier of batteries, chargers and services. EnerSys is the world leader in stored energy solutions for industrial applications. EnerSys manufactures and distributes batteries, chargers, power equipment, and battery accessories to customers worldwide. The company also provides aftermarket and customer support services to its customers from over 100 countries through its sales and manufacturing locations around the world.
More information on Hawker can be found at: www.enersys-hawker.com
More information regarding EnerSys can be found at www.enersys.com.