In the materials handling world, efficient, reliable and cost-effective batteries are essential elements in the reliable and cost-effective operation of electric forklifts, AGVs (Automated Guided Vehicles) and other breeds of industrial moving equipment such as cranes, airport ground support equipment and even industrial trucks.
Lead-acid batteries have long been the traditional choice for materials handling applications, however there is a fast-growing trend towards the use of the new generation of rechargeable lithium-ion (Li-ion) batteries. While Li-ion batteries may appear to be a more complex solution, they are based on tried and tested technologies that have a long track record of delivering high performance, reliability and long life in extremely demanding applications such as spaceflight and Formula 1. Now, we are now seeing Li-ion batteries available on an industrial scale that makes them a viable commercial proposition when their total cost of ownership (TCO) is considered. And there are some applications emerging for which Li-ion is the only viable option.
A major advantage of the Li-ion electrochemistry is its capability to accept very high rates of charge and discharge. On the shop floor, this means less downtime as the Li-ion battery is well suited to fast charging and opportunity charging (brief top-up charging periods), leading to greater availability and no need for swapping batteries out during a working shift. The ability to accept high rate charge and discharge has another advantage, as the battery system can be adapted for regenerative braking.
A second benefit is that Li-ion batteries are essentially maintenance-free, as they are sealed for life, unlike lead-acid batteries that may need topping up with water. Li-ion batteries also offer a long life, both in terms of cycle life and calendar life. So while the initial acquisition costs of a Li-ion battery appear high, the need for reduced maintenance and battery replacement over the operational life of, say a forklift truck, present a powerful TCO argument.
Additional benefits are low weight (lithium is the lightest metal in the periodic table) and compact size – Li-ion batteries have high energy/power density so they can make optimum use of the sometimes restricted installation footprint available.
As a leader in high tech batteries for industry, Saft has pioneered the application of Li-ion technology from manufacturing individual cells to the development of fully integrated battery systems. We believe that this system approach is vital to ensuring the safety and performance of Li-ion battery applications.
This expertise has been employed in the development of the new Modul’ion® modules developed specifically for a broad range of industrial vehicle applications. At the heart of the modules is Saft’s patented lithium iron phosphate cell technology (SLFP™) and built-in battery monitoring and communication that manages battery performance and vital operating data such as state of charge and state of health.
Modul’ion® modules are available in medium and high power versions from 20 V to 40 V, while various combinations of series and parallel assembly enables the creation of battery systems scalable up to 1,000 V.
The successful integration of Saft Li-ion solutions in hybrid industrial vehicle applications is illustrated by the following examples:
Reducing airport emissions
Kalmar Motor AB, the aircraft tractor specialist, is currently completing construction of the world’s first hybrid electric tractor designed specifically for wide body aircraft – the TBL 800 ‘eSchlepper’ – ready for its real-world test programme to commence with Lufthansa LEOS. This hybrid tractor, which combines a Li-ion battery system with a diesel engine, is being deployed at Frankfurt Airport in Germany for evaluation of its performance and life cycle costs compared with conventional ground handling tractors.
Kalmar Motor has developed the TBL 800 eSchlepper to enable airports to reduce their reliance on diesel-driven tractors, helping to address growing demands for lower environmental emissions while significantly reducing running costs. Quiet and emission-free hybrid tractors also offer interesting new possibilities for operating inside buildings, such as workshops and hangars.
The Li-ion battery system powers the TBL 800’s electric drive on a 24/7 basis, it offers excellent energy storage capacity with continuous power capability as high as 100 kW in charge and 400 kW in discharge.
The TBL 800 has its own onboard charger, so it simply needs to be hooked up to an electric point in the tractor parking area or workshop. The diesel engine is used only for charging, to ensure that the battery never becomes fully discharged, and is expected to run for less than 30 percent of the time.
Hybrid RTG port cranes
Another leading-edge application is helping port operators control fuel costs and reduce emissions. The RTG (Rubber Tyred Gantry) crane manufacturer MJ EcoPower has integrated Li-ion batteries into its latest hybrid RTG crane.
RTGs are used to transport and stack shipping containers during ship loading and unloading. Normally, the electric motors for movement and hoisting are powered by a diesel generator that is sized at 400 to 750 kW to power lifting operations but which are kept idling all day for responsiveness.
MJ EcoPower has replaced this engine with a Saft Li-ion battery system and a much smaller diesel genset of 100 to 150 kW that runs less than 30 percent of the time. Conventional lead-acid batteries have been used in similar cranes and have led to fuel savings of up to 70 percent, but the fast-charging capability of the Li-ion batteries means that regenerative energy can be captured as the crane hoist lowers containers, improving efficiency.
Fully electric warehouse pedestrian truck
Saft is using the Modul’ion® modules as the basis for a new 24 V or 48 V battery concept for pedestrian trucks used for moving goods in warehouses. Initial projections indicate that the compact, lightweight design of the new batteries can significantly outperform traditional lead-acid batteries. With the capability to power the truck for two full shifts without recharging, the Li-ion batteries will provide the ideal solution for the 24/7 operation now demanded by modern warehouse logistics.