Patented cell replacement treatment

A project that began in 2010 with just a small team is now picking up global momentum: the resource-friendly process of reconditioning batteries from Mercedes-Benz electric and plug-in hybrid vehicles. We visit the remanufacturing team in Mannheim.

"Center for emission-free mobility", are the words emblazoned on the walls of the production hall. They provide a first indication of what's happening inside: on the one hand, this is the hall where prototypes and small series of vehicles with alternative drive systems are built – while another section of the shop-floor area is devoted to maintain the fitness of automobile energy storage systems. The objective here is to extend the service life of batteries in a vehicle: cells that no longer functioning, for instance, are removed and replaced with new ones. It's a type of processing known as remanufacturing.

The production facility is vast and light. Shades of white and silver predominate, although machines, cables and plastic containers provide splashes of color every few meters. The overall impression is somehow futuristic. Towards the rear of the hall, a taped-off area shows where a remanufacturing line is set up. When the time comes, this is where the EQC batteries for instance will be disassembled, reconditioned and prepared for a return to the road.

Other start-ups are due before then: the first batteries, from the second-generation electric smart built from 2009 on, are expected soon, along with batteries from Mercedes-Benz plug-in hybrid models. "The number of our plug-in hybrid and electric vehicles on the roads has been rising steadily in recent years. We are well prepared for this growing number, and also to reprocess the batteries from them", says Felix Streckert, team leader for the planning and documentation of the remanufacturing process. "Our concept is very flexible. And it needs to be, so that we can cope not only with the different types of batteries but also with fluctuating volumes."

A view of the facility where EQC batteries for instance will be removed, reconditioned and prepared for a return to the road.

Between welding line and test stand

"Our office? This is it!" Jacqueline Barth points laughingly to an area with desks and computer monitors, separated by thin partitions from the "Reman HV Batteries" production area. The mechanical engineer, who is responsible for production and quality within the "Reman" team, likes her unconventional workplace. Right in the thick of the action.

Just ten years ago hardly anyone had any experience in the industrial remanufacturing of HV batteries. As head of a team with two persons, industrial engineer Felix Streckert's remit back then was to investigate whether defective batteries from electric vehicles could be recycled and, if so, what would be involved in doing so. Working with colleagues in process engineering, the team developed a method that would allow the replacement even of individual cells. By doing this, about 95 percent of the original battery can still be used.

Felix Streckert, responsible for planning and documentation of the remanufacturing process on a global basis, and Jacqueline Barth, responsible for production and quality.

The industrial remanufacturing process is well worthwhile in terms of sustainability: by replacing just certain elements rather than complete batteries the consumption of resources, and thus also the CO2 footprint of the battery within the value-added chain, can be reduced. In this way remanufacturing also contributes to optimize the overall environmental performance of EV batteries.

The cell replacement process was patented in 2011 – laying the foundation for today's remanufacturing process. "In the meantime, the number of remanufactured batteries we have supplied runs into four figures. And we haven’t had a complaint about any of them", reports Jacqueline Barth. "It shows, how good our inspection processes and test procedures are."

Back into circulation

The HV battery is one of the most valuable components in the vehicle. So when calculating the economic benefits of local emission-free driving, it is also important to keep the battery in circulation as long as possible. If any damage or malfunction is identified within the warranty period of eight years or 160,000 driven kilometers, the battery will normally find its way back to us, courtesy of the standard battery certificate : in such cases the dealer will remove the faulty battery and replace it for the customer free of charge.

In economic terms remanufacturing is particularly worthwhile, because every remanufactured battery helps to retain value. "Our patented and minimal invasive process allows us to make very efficient use of valuable raw materials. And that gives us a tremendous competitive advantage", explains Sven David, head of the Remanufacturing Operations department.

Sven David, head of the Remanufacturing Operations department.

Long live the automobile

The concept includes the possibility of helping customers to source inexpensive remanufactured parts for their own vehicle at some future point. "The longevity of our products is already a purchasing factor for many customers. As it is the possibility of being able to get new genuine parts when needed", Sven David reports. "The remanufacturing process allows us to offer the further option of using refurbished and tested replacement parts. That is cost-efficient and sustainable, because in this way we are giving our customers the security of knowing that they will still be on the road with our cars in twenty years' time."

It's also the reason why some batteries don't pass the acceptance test. Jacqueline Barth: "It may be, for example, that the charging capacity is below a certain threshold. If that is the case, the batteries are no longer usable by us, but they could perhaps for example be deployed in one of the stationary energy storage systems operated by Mercedes-Benz Energy." Only when that option, too, has been exhausted, the core element of the electric vehicle is finally recycled in an appropriate way. Here, too, the objective is to channel as many of the valuable constituent parts, for example copper, cobalt, nickel and aluminum, back into the materials cycle. The motto is "Reduce – Reuse – Recycle".

Jan Gessner, a member of the remanufacturing team, checks the battery's charging capacity.

Manual processes remain

What is particularly striking when watching the staff at work in their HV protective gear is that, compared with other industrial processes, remanufacturing still involves a lot of manual work. Will that change, if the numbers are set to increase? "There are certainly areas where increased automation would make sense", muses Wolfgang Lesch, a production engineer on the remanufacturing team. "The inspection processes could be completely controlled by machine, as the transfer of the batteries between the various stations could be as well. But, all in all, the reconditioning process is a repair process and can therefore take many different forms." In other words, specialist knowledge and flexible handling will remain.

Wolfgang Lesch is a production engineer on the remanufacturing team.

Over the longer term, demand from all over the world for the remanufacturing of batteries is set to increase significantly. Therefore, Daimler is planning a facility in China. For Felix Streckert, who is involved in the planning, things have therefore now come full circle: "There is still so much potential for further development in this area. Working on the remanufacturing of electric batteries is going to keep us busy for a long time to come."

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