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Fast charging: VW is building charging park buffers from ID. batteries

Instead of laying thick lines, VW is building a buffer store from discarded batteries for the Zwickau plant, which supplies small quick-charging parks.

One of the well-known problems of electric mobility is the charging infrastructure. This, in turn, needs an intact – and above all efficient, power grid. Especially when it comes to fast charging. But this is exactly where it often gets stuck. Because in order to set up a charging park with several fast charging stations, where several cars can charge quickly at the same time, a connection to the medium-voltage power supply is usually required. If this is not available, it becomes difficult or very expensive - at least most of the time.

Because instead of charging electricity directly from the grid, you can also buffer it beforehand. Audi has already shown how this works with the Charging Hub , which uses old E-Tron batteries as buffer storage. You can find the pictures in the gallery above. Volkswagen has now put something similar into operation at the Zwickau vehicle plant.

Old ID.3 and ID.4 batteries as buffer storage

The so-called Power Storage Container (PSC) does not rely on entire car batteries, but uses 96 discarded cell modules from the ID.3 and ID.4 pre-series vehicles . Instead of simply scrapping the components, as is usual with many components, they are given a second life in the PSC and are intended to help ensure more charging power - up to 600 kW at the peak.

The container is only connected with a CEE 125 plug, i.e. a cable with an output of up to 86.5 kW. One becomes eight charging points. Bundled in four Hyperchargers, which are not only supplied via the mains, but also from the 570 kW battery. Four hyperchargers with 75 kW and a 150 kW charging connection are available for e-drivers, each with a maximum charging power of 150 kW.

More flexible, faster and cheaper than mains connection

With the battery alone, almost eleven ID.3s with the large 77 kWh battery (12 modules) could go from 10 to 80 percent SOC (approx. 54 kWh) per day via fast DC -Loading to be loaded. In combination with a small 32-ampere high-current connection, such as that used in the 11 kW wallbox that does not require a permit at home, there are even 5 more vehicles – assuming that the charging point is used ideally. Because with a connected load of 11 kW, the large buffer battery could be half-filled again during the day.

With 11 kW, this is certainly not a suitable scenario for a fast-charging park on the motorway. Jörg Engelmann, the project manager of the PSC at the Zwickau site, also knows this. But especially for car dealerships or for the plant in Zwickau, such containers are a real alternative to the expensive medium-voltage connection including transformer station. Overall, the pilot project cost around 200,000 euros for the charging park."The transformer variant would also cost that," says Engelmann, who is responsible for expanding the charging infrastructure at the VW plant. "In addition, a further 100,000 euros would have been necessary for the more than 100 meters of connecting cable in order to install a charging park that was as fast."

Eleven turns into 49 charges per day

Due to the stronger 86 kW connection of the PSC in Zwickau, the potential of the charging processes also increases. Mathematically, around 49 quick charges or the 10-80 described above are conceivable - and even there there is still room for improvement. "Currently we only have three of the five slots occupied," explains Engelmann. If the other two were also filled, almost one megawatt hour of capacity would be bundled in one container.

Another advantage that Engelmann sees in this system: "Thanks to the containers, our loading park can also be used in a somewhat mobile manner." The term "mobile" is relative. In the current configuration, the system weighs 7.6 tons. If all five battery compartments are full, it weighs 8.1 tons. The dimensions are also far away from the trolley case format. The PSC is 2.5 meters wide, 2.6 meters long and 2.7 meters high and stands on four feet. Engelmann explains that it can also be rolled up for transport.

A total of three of these charging parks are planned in Zwickau. The first, which is now being presented, is supplied with energy directly from a 10 kW wind turbine and a 24 kW solar system in addition to the mains power. "Basically, it doesn't matter," says Engelmann, "because the entire plant has been using renewable electricity since 2017. It's just not produced entirely on site."


The expansion of the power grid is certainly not off the table with systems like the PSC. But in the truest sense, this buffer solution also offers a little time buffer that is still needed for the expansion of the fixed charging infrastructure - especially if the connected load is not to be at wallbox level, but is about fast charging. The principle of regenerative energy generation directly at the charging park makes the whole thing even more exciting, of course, because the green electricity tends to be unplanned and sometimes only dribbles - that's good for charging batteries slowly, which is good for them. And with the large buffer battery, it can also be quickly charged without damage.


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