Ready for use when it lights up blue

More than half a million cars per year and a total area of around 274 hectares: Audi AG's headquarters in Ingolstadt, Bavaria, is the Group's largest production facility and the second-largest car plant in Europe. An Audi model rolls off the production line in Ingolstadt every 30 seconds - that's more than 2,500 cars a day. Around 2,000 industrial trucks are in use in the factory halls.

Quiet and environmentally friendly with electric drives

Audi relies on electric drives for its industrial trucks. The battery-powered devices offer numerous advantages: they can be used flexibly, are quiet, environmentally friendly and low-maintenance. As the company works in three shifts and relies on the constant availability of forklift trucks, pallet trucks and other industrial trucks, many of the vehicles are equipped with exchangeable batteries. Battery charging rooms and stations are located at several locations in the plant, where drivers can swap an empty traction battery for a full one in just a few minutes.

Different colored LEDs on each charger show the status of the connected battery at a glance. Orange means that charging is in progress, green means that it is fully charged and blue indicates that it is ready for use: The battery has cooled down and is therefore ready for use. Photo: Fronius International GmbH

One of these stations is located in Hall T of the freight center. Around 30 traction batteries are stationed there: 48 and 80-volt models with different capacities. Each of the batteries is connected to a Fronius Selectiva charger. The Austrian specialist for battery charging technology and the Ingolstadt-based premium manufacturer have been working together for several years. Fronius launched the latest generation of its Selectiva devices on the market in 2013 - since then they have also been in use at Audi. "Fronius approached us during the development phase of the new devices and offered to work with us," recalls Walter Ferstl, who is responsible for plant logistics planning at the Ingolstadt site. "This allowed us to incorporate our specific ideas and requirements into the development process."

Less energy loss, longer service life

With the Ri charging process, Fronius devices have a completely new technology: the charging current and voltage do not follow a fixed characteristic curve, but are based on the internal resistance (Ri) of the battery. This in turn depends on the battery's age, temperature and state of charge. "This means that every charging process is individual," explains Harald Scherleitner, Head of Division at Fronius Perfect Charging. "This has two advantages: The energy loss during charging is significantly lower, and the heating of the battery is reduced to a minimum." Fronius technology therefore helps users to reduce the total cost of ownership for their industrial truck system.

"The Fronius devices impressed us across the board" Walter Ferstl (left), Plant Logistics Planner at Audi, with Harald Scherleitner, Head of Division, Fronius Perfect Charging - Photo: Fronius International GmbH

Audi initially carried out tests with a prototype of the new Selectiva series. The results were more than satisfactory: "The Ri charging process not only reduces energy consumption, but also CO2 emissions," explains Ferstl. "We can thus make an important contribution to achieving our environmental protection goals." The company has set itself the goal of drastically reducing CO2 emissions at its production sites. From 2010 to 2018, they are to be reduced by 25 percent - partly through the use of new, more efficient technologies. The Fronius devices also impressed in terms of handling: "They are much smaller and lighter than previous solutions, which means they can be installed with little effort, take up less space and are easy to operate," notes Ferstl.

There is also a large charging compartment in the A4 body with around 30 Selectiva devices. Walter Ferstl: "The new chargers are flexibly suitable for all battery types and automatically recognize which model the driver is connecting. Depending on the voltage, capacity and state of charge, the characteristic curve adjusts itself automatically and the battery is always optimally charged."

Display shows the way to the coolest battery

Audi now has more than 300 Selectiva chargers in use at the Ingolstadt site. Different colored LEDs on each charger show the status of the connected battery at a glance. "Orange means that charging is in progress, green means it is fully charged and blue indicates that it has cooled down and is therefore ready for use," explains Harald Scherleitner. On the display of the devices, employees can also see to the minute how long the respective battery has been fully charged. "If the drivers always use the battery that has been fully charged the longest and is therefore the coolest, this improves the utilization of the battery pool and also has a positive effect on life expectancy," reports the Fronius expert.

Boris Ringwald