# Audi’s Battery Testing Center is Balancing Energy Density and Charging Capacity

- Link: https://greenlivingguy.com/2022/06/audis-battery-testing-center-is-balancing-energy-density-and-charging-capacity/
- Published: 2022-06-10T10:03:16-04:00
- Author: greenlivingguy

Electric models must be suitable for everyday use. Purchasing decisions are significantly
affected above all by range, but also by the charging performance of the built-in
high-voltage batteries. For this reason, Audi designs develop, and checks battery
cells and battery components on its own at its battery testing center in Gaimersheim.

Black, red, and gold – these colors indicate the [charging status of a battery](https://greenlivingguy.com/2025/05/ev-battery-charge-breakthrough-for-cold-weather/)
cell. During charging, lithium ions are deposited in the graphite anode, and the
graphite changes its color according to the charging status. When discharged, graphite
looks black; charged halfway, it turns red; and when fully charged, graphite appears
golden.

![](https://i0.wp.com/greenlivingguy.com/wp-content/uploads/2022/06/A223086_large.
jpg?resize=420%2C280&quality=52&ssl=1 "A223086_large - The Green Living Guy")

“This lets us see and assess the charging status,” explains Dr. Bernhard Rieger,
cell expert at the [Audi battery testing](https://greenlivingguy.com/2022/12/test-drive-results-audi-etron-all-electric-sportback/)
center in Gaimersheim. When electrodes are charged, they don’t do so evenly. An 
electrode will charge the most quickly where the highest number of lithium ions 
are present. This results in a charging status gradient. Ideally, everything would
be the same color. But that would require an extremely thin electrode that would
in turn have a neglectable capacity.

“When it [comes to fast charging](https://greenlivingguy.com/2019/07/enel-charging-x-ev-formula-e-plus-coming-to-usa/)
lithium-ion cells, the art lies in precise current control to prevent overcharging
the anode in the golden areas. That would result in premature aging,” says Rieger.“
This means our task lies in ensuring the ideal operation of lithium-ion cells to
achieve the best possible range and charging performance.” For Audi customers, this
guarantees a [battery electric vehicle](https://greenlivingguy.com/2023/04/panasonic-electric-vehicle-battery-kansas-revolutionize-market/)
with both excellent range and charging performance. “Once the basic need for the
range has been met, charging capacity becomes more relevant,” adds Rieger.

## The balance between high energy density and fast charging times

The Gaimersheim cell technicians thus face conflicting goals. “We have a limited
package available to us, into which we have to pack as much energy as possible,”
comments Rieger. “But we also want to be able to recharge it as fast as possible.”

![](https://i0.wp.com/greenlivingguy.com/wp-content/uploads/2022/06/A223089_large.
jpg?resize=300%2C200&quality=52&ssl=1 "A223089_large - The Green Living Guy")

The conflict lies in the fact that the greater the energy density, the longer it
takes to charge the cell. This means the cell technicians are facing a balancing
act that requires them to at least keep [charging times constant while increasing energy](https://greenlivingguy.com/2025/07/charge-with-ev-grid-energy-myths-vs-reality/)
density. In order to charge a lot of energy quickly, charging [capacity](https://greenlivingguy.com/2010/10/ev-charge-network-key-players-and-developments/)
is an early point on the agenda for project development.

In this area, no less than two Audi models are setting standards today: The cells
in the 93 kWh high-voltage battery used in the Audi e-tron GT quattro^(1) can [charge](https://greenlivingguy.com/2025/09/used-ev-battery-energy-for-virtual-power-plants/)
from 5 to 80 percent with up to 270 kW of power in only 22.5 minutes in ideal conditions.
The Audi [e-tron](https://greenlivingguy.com/2022/11/2022-and-2023-model-year-q4-e-tron-and-q4-sportback-e-tron-models-meet-requirements-for-highest-honors-from-iihs/),
which first hit the market in 2019, is still considered the benchmark today with
its unique plateau-like charging curve, where the charging power of up to 150 kW
is available for a large part of the charging process.

## From test stands to pre-series production – everything under one roof

In addition, the battery cells also meet the highest service life and safety standards.
To this end, the individual cells and the battery system as a whole have to pass
numerous tests. That’s at the approximately 4,400-square-meter center in Gaimersheim.
Each vehicle project entails a variety of service [life and fast charging](https://greenlivingguy.com/2026/07/ai-battery-charge-extend-your-ev-battery-life/)
tests on several hundred cells. The cells have to run through different charging
and load profiles. The Gaimersheim technicians perform it in climatic chambers at
temperatures between -30 and +60 °C.

“Our tests and checks begin at an early sample phase about four years before the
start of production to allow us time to make readjustments where necessary”, explains
cell expert Rieger. In order to assess the cells’ aging phenomena, techs expose 
them to high temperatures for the space of about a year.

![Audi's battery testing center is balancing energy density and charging capacity](
https://i0.wp.com/greenlivingguy.com/wp-content/uploads/2022/06/A223077_large.jpg?
resize=420%2C280&quality=52&ssl=1 "Audi's Battery Testing Center is Balancing Energy
Density and Charging Capacity - The Green Living Guy")

This allows [Audi](https://greenlivingguy.com/2022/08/audi-s1-e-tron-quattro-hoonitron-will-make-north-american-debut-at-rolex-motorsport-reunion/)
to simulate an in-car service life of up to 15 years. Service life test stands in
Gaimersheim also allow the technicians to speed up reconstructed mileage scenarios
of about 300,000 kilometers. Other tests include crash and overcharge testing as
well as various safety tests. Techs can simulate diverse driving scenarios in order
to optimize the high-volt components’ operating strategy or thermal management.

“This application allows us to perform the best possible fine-tuning on our batteries,”
says Rieger. “New findings from cell measurements are rerouted right back to the
virtual battery models. Therefore, we can observe the effects on the vehicle.” Gaimersheim
is also home to a construction facility for prototype [batteries](https://greenlivingguy.com/2014/01/dow-building-insulation-products-achieve-recertificatio/);
here, employees build the high-voltage batteries from the ground up all the way 
to pre-series production.

Source: [Audi](https://www.audi-mediacenter.com/en/press-releases/audi-battery-testing-center-in-gaimersheimwhere-range-and-fast-charging-come-together-14669)

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 greenlivingguy

 The Green Living Guy, Seth Leitman is an independent power producer, a green living
expert, and Editor of the McGraw-Hill, TAB Green Guru Guides. Seth is also an Author,
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Green Living Guy writes about green living, green lighting, the green guru guides
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