Saturday, January 22

How electric car batteries are built and tested: this is what a battery test center looks like on the inside

The Energy Test Center inaugurated this week by Seat is the first battery test center in southern Europe. We have been able to visit it and find out what kind of developments and tests are carried out in this pioneering building. A 1,500-square-meter complex in which more than 7 million euros have been invested and where cell modules and batteries for electric cars and plug-in hybrids are tested.

Batteries are the key component of an electric car, which many already simplify as “a computer attached to a battery and four wheels.” But the process of building and testing a battery is much more complex. Here we tell you what steps are necessary for its manufacture and what type of tests are carried out in a center such as the one built by Seat in Martorell, Barcelona.

This is the interior of electric car batteries

Batteries are made up of modules. In the case of the 58 kWh of the Cupra Born, we have up to 9 modules and a combined weight of 376 kg.

Spain is the fourth country where the Volkswagen Group decides to build a battery test center. Outside of Germany, the manufacturer has a similar center in China and the United States. As explained from Seat, the open in our country is larger than the American. This Test Center Energy (TCE) is a test center, but batteries are not manufactured here. It is still pending confirmation where the Volkswagen battery giant factory in Spain will be located.

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The first step in the construction of a battery is the extraction of the necessary minerals, mainly lithium. In Spain, the first lithium ion battery factory will be in Badajoz, to take advantage of the exploitation of the Las Navas lithium mine. It is not ruled out that Volkswagen wants to place its gigafactory in a similar location.

After collecting the lithium, cobalt and other necessary minerals, it is time for the preparation and mixing of the active material. With this the electrodes are created, separating anode and cathode. Later is where the assembly of the cells, organized in modules and finally in the batteries themselves. The batteries, which usually operate at 400V, connect in series more than 100 cells grouped in modules.

It is in the test center where it is determined that both cells, modules and batteries meet the necessary requirements for their use, from the thermal aspect to the safety aspect. In total, some 6,000 different analyzes are carried out, explains Werner Tietz, Seat’s vice president of R&D.

Seat Battery Life Tests

Batteries are subjected to an average of more than 17,500 hours of tests with the idea of ​​guaranteeing their performance throughout their life cycle.

Depending on whether it is a capacity battery (for electric vehicles) or a power battery (for hybrids), the machines used can be different. From Seat they explain that they work both with batteries with a capacity of 13 kWh, such as that of the León PHEV, up to 77 kWh, which we see in the Volkswagen ID.5 and in the future Cupra Tavascan.

According to Francesc Sabate, Head of Development of the High and Low Voltage Battery Laboratory at Seat, the main difference between batteries of more or less capacity is in the distribution of modules and cells. In the case of the 58 kWh of the Cupra Born we have 9 modules and a total weight of 376 kg, where each module alone weighs about 32 kg. In the 77 kWh, more modules are added and the cells are distributed differently.

Electric Car Battery

In the center, both capacity batteries for electric cars and power batteries (in the image) for hybrid cars are tested.

In addition to cell modules, batteries incorporate other elements. We have the top cover, which is what protects the internal system and helps to give the battery structural rigidity. We have the communication and measurement cabling, module connectors, a cell and module controllers, the cell modules themselves, a battery box to give internal rigidity and connecting connectors between the cell modules. Finally, a cooling plate is also added to compensate for the heat generated.

In the case of MQB batteries for electric vehicles we have a different arrangement. There they bet on cooling pipes and a pressure compensation valve is added. The number of cell modules is considerably less.

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Up to 6,000 different analyzes

Tce Up to 6,000 complete validation analyzes are carried out in the Test Center Energy.

Seat’s battery test center has a testing capacity of 1.3 megawatts, a power equivalent to having 100,000 mobiles charging simultaneously. 25 technicians and engineers are working at the facilities and we were able to observe how the different sections that are active work.

The TCE has a programming room, where algorithms are developed both for testing specific events and for the computer vision camera. Of the 6,000 tests, half are for functional safety. That is, facing the batteries to extreme events to see how they respond. As described by Seat, a car like the Cupra Born has about 100 million lines of code.

Programming room

Programming room.

The batteries undergo validation tests related to the high voltage system (battery, charge and safety) and one of the intentions is also to verify that they are capable of performing throughout their life cycle. For it undergo an average of 17,500 hours of testing. According to Seat, a useful life of its batteries is ensured in about 8 years or about 160,000 kilometers, where after that time they maintain 70% of the capacity.

Seat Test Interface

For testing, engineers have customized graphical interfaces with the most relevant data on the state of the batteries.

A large space is occupied by different climatic chambers. They have cameras with a power of up to 300kW for electric car batteries up to 21 kW cameras for mild-hybrid variants. Those responsible for the center explain that not only are tests carried out for the batteries of Seat or Cupra cars, but that receive orders from the Volkswagen Group for models that will not be produced in Spain.

Climatic Chambers

With the different climatic chambers the batteries are tested under extreme thermal conditions, between -25 ºC and +55 ºC.

These climatic chambers have safety mechanisms such as solenoid valves or gas extraction and allow checking the thermal resistance of the batteries. Tests are carried out between -25ºC and + 55ºC, although they assure that the cameras are prepared to reach -55ºC and + 120ºC. The climatic chambers of the TEC are new, except for one of them that has been reused and approved to be able to work with batteries for the whole group.

Batteries represent between 30 and 40% of the cost of the electric car

Functional Safety

The battery test center inaugurated by Seat, the first of its kind in southern Europe, has a testing capacity of 1.3 megawatts.

The inauguration of the battery center was attended by Wayne Griffiths, CEO of Seat and Cupra and Diana Morant, Minister of Science. This project is part of the € 5 billion investment that the German manufacturer will make in Spain in its bid to electrify the company. Its construction lasted a year and a half and they began to work after the summer, now being their official opening.

Wayne Griffiths

Wayne Griffiths, CEO of Seat and Cupra, during the inauguration of the Test Center Energy in Martorell.

Batteries are one of the most important elements for the electric car and they point out that they end up representing between 30 and 40% of the cost of the vehicle. The center also has a workshop designed to test electrified vehicles, being able to test up to 8 cars at the same time. This is where tests of energy, functional safety and the integration of the functions with the electronics of the car are carried out, for example if there is an overload a warning is displayed to the driver.

Car Tests

Electric vehicles are tested for energy, functional safety and integration of functions with all electronics.

When conducting the tests, we see different Seat and Cupra vehicles connected to control units that allow diagnostic tests to be carried out. From the company they explain that they have been programmed custom interfaces to quickly view some data.

They also have computer vision cameras installed inside the vehicle that allow them to point to the screens that the driver sees and thus check if the respective symbols and notices related to the batteries appear. Technicians subject the car and its battery to different situations and see how the vehicle responds.

Vision By Computer

Supported by a computer vision camera, algorithms are generated to replicate extreme fault situations and see how the battery responds.

The center has a high voltage battery warehouse and a space for “open innovation”, referring to offices where they allow universities and external companies to establish themselves and take advantage of the machinery of the test center for their studies and projects.

In addition to electric and hybrid cars, the battery test center is also used for Seat’s electric motorcycles and scooters of the MÓ series.

Electric Motorcycle Batteries

The batteries of electric motorcycles and scooters also undergo tests similar to those of other vehicles.

Outside the building there are six charging points to check bidirectional functions and that the charging is carried out correctly. The SEAT team explains that they plan to install a 350 kW charging point Before the end of the year. A fast recharge that is the holy grail of electric cars and where in this test center they will also have the responsibility of verifying that it works as it should.

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