Co-operative Food Retail Logistics called on EnerSys to help optimise the warehouse space at its new distribution centre at Birtley in County Durham by minimising the area required for charging warehouse truck batteries. The solution was to build a three-tier battery bank – with potential to go even higher – served by a unique electric-powered changing cart, believed to be the first of its type in the EU to work without hydraulics.
This novel installation forms part of an advanced battery management system to meet Co-operative Food Retails Logistics’ key objectives of best practice and sustainability. Sophisticated charging and allocation procedures as well as remote diagnostic facilities ensure optimum performance over an extensive projected working life for the batteries and warehouse trucks.
"This new installation continues the policy employed at our other sites and provides a good benchmark for the group," says Chas Shepperson, National MHE Fleet Manager at Co-operative Food Retail Logistics. "We have a strong relationship with EnerSys and they went out of their way to listen and devise what we wanted."
The new 285,000 sq ft (26,500 sq m) distribution centre opened in April 2009 and incorporates ambient, chilled and frozen storage. From here goods will be distributed to 260 Co-operative stores throughout the North East and Scottish Borders.
The Birtley site has been designed from the ground up to incorporate state-of-the-art equipment to support efficient and sustainable operations. Advanced voice picking technology helps the 500 distribution staff on site to fulfil over 200 deliveries a day and pick half a million cases a week. The aim is to pick down to a single item if needed. To meet the projected workloads Co-operative Food Retail Logistics selected a fleet of 61 warehouse trucks from its MHE partner Linde. These include pallet transporters, low level order pickers and reach trucks which handle to the fifth-level top beam at 11.455m – the highest currently in any of the business’s warehouses.
From its experience at other depots, Co-operative Food Retail Logistics had a good understanding of its requirements for the battery system. This required the elimination of manual handling and lifting of batteries and the adoption of the latest technology for battery management, charging and changing. It was important that by minimising the overall footprint of the charging area to allow more space for storage, operational flexibility was not compromised.
Co-operative Food Retail Logistics has a long-standing relationship with EnerSys and over 90% of the 2000+ batteries used across its 19 warehouses are Hawker Evolution units. With a gelled electrolyte, Hawker Evolution offers a number of maintenance-free benefits because its sealed units require no topping up and there is no risk of spillage. A highly efficient valve-regulated re-combination technology reduces gas emissions to an absolute minimum which makes Evolution ideal for busy food distribution operations.
"We started with Hawker Evolution batteries in 2001 and they’ve got better as we have," says Chas Shepperson. "The trucks at one of our other sites are still using batteries originally supplied back then. Gelled electrolyte means there is no spillage so they are safer and there are no problems with corrosion. Reduced gassing means we don’t need special ventilation. The training required is also much simpler. Evolution is a good battery."
From the outset it was clear that the best way of minimising the charge area foot print was to create a bank of multiple tiers to accommodate the batteries on charge. Co-operative Food Retail Logistics successfully pioneered three-level banking at recent developments in Coventry and Thurrock. While the initial plan at Birtley was for a similar configuration, there was the potential for a fourth tier to cope with future growth. Both companies accepted that four-high could be beyond the performance of the existing Hawker Pro Series BBH bull handling equipment because its hydraulic systems were at their design limit. The only practical solution was for EnerSys to devise a new version of the BBH with fully electric capability to remove any potential restrictions. This completely new model is the first of its type delivered by EnerSys and is believed to be unique to any supplier in Europe.
Co-operative Food Retail Logistics was keen to build redundancy into the new system to ensure it could maintain continuous warehouse truck operations. The solution was simple and elegant with two identical banks, each with space for 42 batteries, arranged back-to-back with their own BBH. This means one of the systems can be taken off-line for maintenance while the other continues to supply charged batteries. An added advantage of this layout is that the central aisle running between the two banks allows engineers to check, monitor and maintain the chargers without entering truck operating areas. This promotes safety and ensures essential maintenance work can continue without disrupting normal warehouse operations.
"With this arrangement we can keep the site operating at all times," says Chas Shepperson.
The Pro-Series BBH is a semi-automated electric powered change cart that runs on concealed rails alongside the row of chargers. When a change is required, the truck approaches the changing area and the driver disconnects its battery. The trained member of staff dedicated to the battery area then takes over and completes change.
A powerful extending electro-magnet on the BBH extracts the battery from the truck onto its on-board roller bed and then pushes it into place for charging. The device can be raised to handle batteries on the second and third levels in the charging banks. With the BBH the whole process is a very quick and simple one-man job which helps sustain truck uptime and eliminates potentially injurious manual handling.
"We generally expect to change a battery in around 90 seconds," says Chas Shepperson.
Co-operative Food Retail Logistics uses EnerSys’ Powertech HF chargers which offer outstanding energy efficiency, as much as 20 per cent higher than 50Hz chargers. The chargers automatically detect 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 and the energy costs per charge are considerably reduced, leading to significant savings in electricity costs. With the Evolution battery these savings can be as much as 30 per cent.
To ensure maximum efficiency and performance from the power sources all operations are overseen by the advanced EnerSys Battery Management System. The ‘intelligent’ diagnostic software in the chargers transmits data via the system’s PC to a large display screen installed in the battery changing area. The display clearly indicates the order in which batteries for each type of truck should be retrieved, ensuring that only fully-charged units are taken. This makes certain that all batteries receive the correct amount of charge before being used, and that they are systematically rotated, overcoming the potential problem of operators simply taking the nearest available battery, regardless of its true state of charge. The system also ensures that batteries are charged during lower tariff overnight periods wherever possible to generate a further cost saving.
Battery efficiency is also optimised which means utilisation can be aligned closely to operational requirements. There is also no need to source two spare batteries for each truck, as Co-operative Food Retail Logistics did in the past, because the balanced charging ensures that the equivalent of one spare is enough. This has delivered considerable capital savings for the group, leaving aside the smaller space required to store fewer batteries.
The management system operates in conjunction with the remote monitoring and diagnostic Powernet service from Enersys. At any time managers from EnerSys can connect to the management system from their own sites and download a wide range of battery related information. This allows them to analyse and assess overall performance and prepare reports for Co-operative Food Retail Logistics. Metrics available include battery status, batteries used, amps available, amps used, power usage, depth of discharge, charger faults by type and recent alarms. Engineers can also isolate individual batteries and carry out diagnostic tasks to identify specific problems. Information can then be relayed to the warehouse’s own team of on-site engineers to help them carry out pre-emptive preventative maintenance.
Birtley has been developed with 25 per cent residual capacity to provide a degree of future proofing for the business. In addition to the battery systems, many other aspects of the site have been devised with sustainability in mind: the lighting automatically adjusts to match external conditions with reduced overall energy consumption; a seven-stage rainwater collection and filtration system provides water for use in staff toilets and vehicle washing; packaging is returned to the site from stores for recycling in a state-of-the-art combined shredder and baler.