Breathing new life into battery technology

Daimler has developed a unique concept for an active battery spare parts storage facility that is being put into operation in Hannover. Instead of simply stacking the batteries in a high-bay storage facility, the 3,000 or so batteries for the latest fleet of smart electric drive vehicles will be combined to create an extra-large stationary storage unit in Lower Saxony’s state capital. After the site in Lünen, where Daimler has set up the largest second-use battery storage unit in the world in partnership with The Mobility House and GETEC, this facility represents a further step towards optimising the balance between the environmental impact and the cost of electromobility.

16 megawatt output

The storage facility in Hannover will have an output of 16 megawatts and will be put into operation this year in collaboration with Enercity (Stadtwerke Hannover AG).

What’s more, Daimler is investing €500 million on expanding the Accumotive site in Kamenz, Saxony, where the batteries for the Mercedes electric vehicle fleet are made. Production has already started there on the stationary storage units for use in private households. “We are seeing an encouraging level of demand for these as well and have already sent the first few units out for delivery to private customers,” says Kröger. Daimler is working in partnership with EnBW and SMA Solar Technology AG to have the first few units installed in private homes in the coming days.

Good for the batteries and for energy efficiency

Storage technology at Daimler not only plays an important role in mobile applications. The actively stored batteries in Hannover make an important contribution to stabilising the power grid in times of renewable energy sources such as solar and wind power, because they smooth out the unavoidable energy fluctuations with virtually no loss. But it’s not only energy management that benefits from this ‘breathing’ energy storage facility. The batteries themselves do too. To ensure that such batteries can be used at a later time without problems, they have to be regularly charged and discharged during storage to avoid deep discharge, which could negatively impact their performance.

That said, this type of storage is not beneficial for all battery types. Batteries from hybrid models are unsuitable because “these hybrid batteries are designed with performance in mind and not for energy content. That is why we would not consider them for a stationary storage facility like the one in Hannover,” explains Kröger. At a push it would be possible to use the batteries for the plug-in models for this kind of facility.

Fountain of youth for batteries

Thanks to the highly advanced battery management system at the Daimler subsidiary Accumotive, the batteries in Hannover always stay in optimum condition. If they are needed as a replacement battery for a smart car, they meet the same quality and durability requirements as they did on day one. This is because this type of storage effectively works like a ‘fountain of youth’ for the batteries thanks to the controlled conditions – they are stored at a constant temperature with no vibrations and without excessive stress brought on by impatient drivers.

This technology can also be used at Daimler manufacturing plants to ensure the optimum use of energy in production. “We are thinking about how we can use these storage units as a buffer at sites where we have experienced power outages, such as in South Africa,” says Kröger, looking ahead to the future. However, the customers are the first priority, given the interest they have shown.

The ‘breathing’ energy storage facility is designed in such a way that batteries can continually be removed and, as Kröger says, “the output is continually powered down. At the same time, we are also able to replace the removed batteries.” The method chosen also depends on the partner. Irrespective of that, this new business model makes an important contribution to stabilising the power grid and to the economic feasibility of electromobility. You could therefore say that the batteries being stored in Hannover do their bit for sustainable mobility without even being used on the road.