Tow truck being rechargedAudi is trialling fork-lift trucks and tow tractors powered by used lithium-ion batteries at its main plant in Ingolstadt, Germany.

The development is the latest stage in the company's research to find second uses for used batteries. Like all OEMs, Audi is obliged by law to take back batteries once their life in a car comes to an end.

After successful initial trials with converted factory vehicles, the company is now testing them in everyday operations.

If the entire fleet of factory vehicles across the company’s 16 production sites worldwide were powered by second-use lithium-ion batteries, the OEM says it would “save millions.”

However, if anwhen the roll out takes place has not yet been decided since the work is still at a trial stage, a company spokeswoman told Automotive Logistics.

Fork-lift trucks and tow tractors have traditionally been powered by lead-acid batteries, meaning when the batteries are empty, workers have to remove battery packs weighing up to two tonnes before connecting them to a charging station for several hours.

Lithium-ion batteries have the advantage of being charged directly wherever a vehicle is parked during normal downtime, such as breaks between shifts. “This saves space and also eliminates the high manual effort required to replace the batteries,” the company said.

Batteries from Audi e-tron test vehicles and hybrid models, like the A3 e-tron and Q7 e-tron, are being used in the Ingolstadt trials.

The lithium-ion batteries still have a large proportion of their original charging capacity, which is more than sufficient for factory vehicles’ requirements.

“They can keep their speed constant even on ramps; factory vehicles powered by lead-acid batteries cannot do that. In addition, regular charging during breaks prevents downtimes during working hours,” said Audi.

The e-tron’s battery consists of 36 individual modules, fitted as a flat, wide block. When the batteries are returned, the re-use project team checks each module for continued usability, then installs 24 modules in each new battery tray.

“This has the same dimensions and weight as the previous lead-acid batteries of the factory vehicles, so the company can continue to use all of those vehicles without any major investments,” Audi said.

Peter Koessler, member of the board of management for production and logistics at Audi, commented: “Every lithium-ion battery represents high energy consumption and valuable resources that must be used in the best possible way. For us, a sustainable electric-mobility strategy also includes a sensible second-use concept for energy carriers.”

Looking ahead, Audi said a specialised team could take over assembly of second-use batteries at the company’s own battery centre, while it is also possible that used battery modules could be used in stationary energy-storage systems or in mobile charging containers for electric vehicles.

That was trialled at this year’s World Economic Forum, where Audi supplied three mobile charging containers, powered by used batteries from electric cars, to recharge the shuttle fleet of 50 e-tron cars the company provided for the gathering at Davos, Switzerland. Audi envisages the mobile containers being used at major events to supplement local charging infrastructure.

In addition, the company is working on recycling so that at the end of a battery’s life its valuable elements can be used in new products.