An advanced battery management system that manages change and charge operations for warehouse truck batteries has been installed by Ventura Network Distribution at its massive state-of-the-art distribution centre at Wath on Dearne. The installation is designed to optimise the performance of Ventura’s warehouse truck fleet over the entire five year contract, minimise energy consumption and provide the company with flexibility to adapt its operations in line with business requirements.
"We are looking for good performance from the batteries and warehouse trucks through to year five of the contract," says Harry Dooley, Group MHE Manager for Ventura Network Distribution. "The EnerSys battery management system will allow us to manage the batteries over the whole lifetime and help us reduce overall costs and power consumption."
The Wath on Dearne distribution complex near Rotherham was opened in 2007 by Ventura Network Distribution to offer a complete logistics operation for its fashion and home accessories customers. Two massive warehouses on the site stock a complete range of clothing and household items supplied, stored & distributed for retail and home shopping customers. Operations are split between general pallet handling and order picking. The materials handling fleet includes powered pallet trucks, counterbalance trucks, reach trucks and VNA trucks supplied by Crown. The majority of the trucks operate in one of the warehouses because the other is mostly automated for pallet and case handling. Capacity is still growing and there is room for expansion, for example by adding mezzanines in the main picking warehouse.
The new development presented an ideal opportunity to introduce best practice across the entire operation. The company recognised that warehouse truck batteries at its other sites were becoming unreliable and inefficient before the end of their projected lifetimes and it wanted a better solution at the new facility.
"Some batteries at other sites were nearing the end of their life prematurely due to improper charging practices," says Harry Dooley. "We wanted a new system that forces proper charge and change operations."
During its truck selection process Ventura asked the potential suppliers who they would recommend for the batteries. A number mentioned EnerSys as a specialist who could demonstrate a track record in similar applications with their own equipment.
"Our criteria included having all battery management facilities in one place, making better use of the available space and working with an optimised specification," says Harry Dooley. "EnerSys ticked all our boxes and appeared to be best for the purpose."
The lift truck supplier worked with Ventura and EnerSys to agree the final specification for the battery management system. Unlike smaller warehouses, which tend to have a single battery installation, it was decided to have separate charge and change areas located throughout the warehouse close to where specific types of truck are operating. The battery area for the 40 order picking trucks, for example, is on the mezzanine floor of the main picking and order assembly warehouse. The precise position was finalised during the warehouse planning phase to take into account the pick paths and one way system employed in the area. It is also against a wall and close to one of the ventilation points for convenience.
EnerSys supplied 80 of its high-performance Perfect Plus batteries which offer extended work cycles between charges for the order pickers. Charging is achieved using Powertech high frequency chargers which are up to 20 per cent more efficient than traditional 50Hz units. Powertech automatically detects the battery’s level of discharge and supplies only the amount of power needed, and no more, to restore full charge. This means less power is required to charge a battery with significant savings in electricity costs.
At any time 40 batteries are being charged along a bank of 42 charging stations. When a truck needs a fresh battery it pulls up alongside the area where a large overhead screen indicates the position and identity of the next available unit. The EnerSys management system ensures batteries are allocated in strict rotation so that the best available unit – the one which has been in a fully charged condition the longest – is always used. This overcomes the potential problems associated with operators simply taking the nearest available battery, regardless of its true state of charge. Battery utilisation is spread more evenly 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.
Charging points are numbered while batteries have alphabetical identities to reduce the risk of confusion. If a truck operator takes the wrong battery by mistake a loud alarm sounds. Battery changes are completed manually by rolling the depleted battery from the truck onto a special rail mounted carriage that runs in front of the charging positions for transfer to a free position. The correct fully charged battery is then taken to the truck using the same carriage. The two extra charging positions ensure there is always a free location for the depleted battery before the fully charged unit is retrieved. This minimises space requirements, provides greater flexibility and eliminates the need to move a truck during the change.
"It’s so easy and operators don’t take the wrong battery," says Harry Dooley. "It needs to be clear and simple because we have a diverse workforce."
The separate charge and change area used by the larger trucks operating on the mezzanine uses an identical management system with similar batteries and chargers from the EnerSys range. Instead of a dedicated display panel this area relies on the system’s own management screen to indicate the next available battery.
The reach truck facility on the ground floor is designed along similar lines although this required even greater flexibility to cope with the influx of temporary trucks needed to meet peak demands in the run up to Christmas.
"We are good at engineering and change ideas regularly to rise to new challenges in the business," says Harry Dooley. "We have a proactive can-do mentality and choose suppliers who can work with us and react."
In each area the installation has been designed with expansion in mind. Additional chargers and battery positions can be added easily by extending the frames and connecting the devices using bus bars. This provides flexibility to accommodate new and different trucks and batteries in the future to meet evolving materials handling requirements.
"The large battery area on the mezzanine has grown already and there is still room for one more position without any modifications to the installation," says Harry Dooley. "With bus bars it’s easy to add extra chargers."
Ventura was keen to use the information available from the battery management system to get the best possible performance from its investment. Regular meetings on-site with the EnerSys team help to identify any emerging issues or requirements before they impact on the operation. When the warehouse was opened management reports were available every quarter to provide metrics including battery utilisation, performance and maintenance. Ventura plans to move to shorter periods so that it can act more quickly using detailed and current information. The company has already recognised that the experience at Wath on Dearne can be applied to the other warehouses it operates.
"If you don’t get the information back and start making decisions you are wasting your money," says Harry Dooley. "EnerSys gives good clear information and this will help us to adapt quickly. We perceive this as best practice and believe that after five years we will still have batteries that we can use."