Chattanooga Power Haus

Volkswagen sprints forward in the EV race by integrating battery test, production, and EV assembly in the U.S.

The drive-in temperature chamber at Volkswagen of America's Battery Engineering Lab (BEL) can accommodate vehicles as large as the company's Atlas SUV. (VW)

Volkswagen is rapidly gaining on General Motors, Ford and Tesla in terms of overall EV development and production assets in North America, industry analysts tell SAE Media. With the recent launch of its $22 million Battery Engineering Lab (BEL) near Chattanooga, Tennessee, VW becomes the first non-domestic OEM to fully integrate battery test and validation, pack assembly and EV manufacturing in the U.S. The 32,000-sq.ft BEL is adjacent to VW’s vehicle and pack assembly complex and includes in-house test capabilities that in some metrics surpass those of the top three domestic EV makers, battery R&D experts indicate to SAE Media.

The BEL’s water immersion test is a Polar Bear Club for batteries. (Lindsay Brooke)

“We are transforming this region into a powerhouse for EV production, including suppliers,” asserted Johan de Nysschen, Volkswagen Group of America’s COO, during a tour of the BEL in June 2022. De Nysschen said VW is moving to full vertical integration of EV batteries in the U.S., including prismatic-cell manufacture and recycling. The plan is being implemented by PowerCo, VW’s new wholly owned €20-billion battery organization. A new U.S. cell plant, expected for the Chattanooga area, will be based on a standardized factory design, the first of which is now under construction in Salzgitter, Germany. Salzgitter is designed for 40 GWh annual capacity and will start production in 2025. Six factories built on the Salzgitter “blueprint” currently are in the works for Europe. Each cell plant will be 100% powered by electricity from renewable sources.

The battery pack for VW's ID.4, a vehicle recently added to the assembly mix at the company's manufacturing complex in Chattanooga. (VW)

VW’s strategic electrification goal is to “unite our operations in the U.S., Mexico and Canada,” de Nysschen said.

In the near term, VW will source its U.S. EV battery cells from SK Innovation at the new $2.6 billion factory SKI is building in Georgia. VW expects production scale generated by PowerCo’s standardized cell and production scheme will reduce battery costs by up to 50% and ensure high quality, Dr. Wolfgang Demmelbauer-Ebner, VW America’s chief engineering officer, told SAE Media.

The eMAST shaker table is key to developing new EV packs. (VW)

The new BEL also is likely to be used to test and validate batteries for Navistar commercial trucks (part of VW-owned Traton Group) as well as a new generation of Scout SUVs, according to Scout CEO Scott Keough, who spoke with SAE Media at Chattanooga. Demmelbauer-Ebner said “now that we’re brothers and sisters with Navistar, it makes sense to share the ‘center of gravity’ and big investment we have here in Chattanooga with them.”

Shock, dust and immersion

The Thermal Shock chamber has enabled engineers to reduce testing time by more than two weeks. (Lindsay Brooke)
Dr. Wolfgang Demmelbaur-Ebner. (Lindsay Brooke)

A comprehensive tour of the BEL led by Wolfgang Maluche, VP engineering, revealed the majority of test cells to be WW-series equipment sourced from Weiss Technik North America, based in Grand Rapids, Michigan.

Electrical Multi-Axis Shaker Table (eMAST): With an array of six actuators each capable of generating 16,000 lb (71,171 N) of force, under the control of an MTS digital computer, the BEL’s eMAST performs extreme vibration tests to simulate more than 9,000 miles (14,484 km) of driving in seven days – in varying climate conditions. The rig can administer acceleration shock up to 16-g to a 2,200-lb. (998-kg) battery-pack payload, in a thermal range of -40 deg. to 158 deg. F (-40 deg to 70 deg C). The eMAST closely monitors all cell parameters via the pack’s CAN bus and is capable of rapid load cycles, charging at 1,000V/900kW at 800A, and discharging at 350A. “The eMAST will influence our future pack structure design and engineering,” Maluche said.

Thermal shock chamber: This Weiss Technik unit engineered for extreme durability testing “is vital for speeding battery development and validation,” Maluche noted. By running 40 thermal-shock cycles in just three days, the chamber reduces the typical thermal-shock testing cycle by 17 days, he said. Capable of generating temperature deltas from -40 deg to 158 deg. F, it’s the best equipment with which to fully simulate EV battery cell and pack life (including welds, seals and fasteners) through a Michigan winter, which VW engineers deem to be the most extreme cold-weather use case. VW is currently sharing this test chamber with battery partner SKI.

Drive-in temperature chamber: Measuring 20 x 16 x 11.5 ft, this space is more than large enough to accommodate the largest SUV (Atlas) currently in VW’s lineup, or two ID.4s. This Weiss Technik WW-series chamber was immediately in big demand for evaluating batteries across the wide spectrum of North American climatic/stress scenarios, Maluche said. Thermal capabilities range from -112 deg. to 356 deg. F (-80 deg. to 280 deg. C), with a ramp rate of 3 deg. C per minute. Keysight supplied its pack-level Scienlab Battery Test System and its Energy Storage Discovery software for this important lab, which has 1,000V/900A/360kW battery-charging capability.

Dust chamber: Supplied by Italy-based ACS Angelantoni Test Systems, the BEL’s sophisticated dust chamber uses ISO-standardized dust particles, fed at flow rates up to 2,600 cfm to replicate 70 mph (113 km/h) road speed, to attack the test pack’s seals. The ISO-certified “Arizona” dust particulate measuring 1/70th of a human hair in diameter often is blended with abrasive material. A typical dust test at BEL is 20 cycles at 20 minutes per cycle, over approximately seven hours. This would be part of a sequence of battery-pack tests that begin with a thermal cycle, then the dust test, water-jet test at garden-hose pressures, followed by a high-pressure steam test. The pack then is completely disassembled and analyzed.

Water immersion and sodium chloride: Salt-bath tests that simulate up to one year of EV life in a hostile winter environment (such as southeastern Michigan) and a water-immersion test that simulates water ingress after shocking the aluminum case structure, are keystones in VW’s pack development. The 2,100-gal. (8 m3) water-immersion tank, supplied by Florida-based Equilam NA, heats the pack structure to 140 deg. F (60 deg C) before dunking it into 40 deg. F water (dyed a color, for easier leak identification) for five minutes. Each immersion test cycle includes 20 tests that are like a Polar Bear Club outing, but for battery cases.

Battery standardization “not quite yet”

SAE Media had an opportunity at the Chattanooga media event to pose a handful of questions to Dr. Wolfgang Demmelbauer-Ebner, VW’s chief engineering officer:

  • EV battery technology still is in a state of flux, with competing chemistries, form factors, etc. Does VW see a standardization coming?

    Not quite yet. There is more to come in the chemistries, including solid-state batteries within the next 5-10 years. And the form factors will continue to be fluid, as OEMs change them to meet different vehicle applications – high-floor cars, low-floor cars, wide and narrow battery packs depending on the vehicle architecture. We are a global manufacturer and have to build vehicles for different customers and regions, so there will not be a single form factor perhaps for quite a while.

  • Do you see the 12V lead-acid battery being designed out of EVs to save weight and complexity?

    No, not any time soon. The 12V battery is inexpensive, reliable, recyclable and has high energy density for a number of use cases.

  • What role will your R&D partners from Oak Ridge National Labs and University of Tennessee be playing in VW’s EV developments in Chattanooga?

    Many roles. They have huge expertise not only in batteries but also in other areas of propulsion technology. We have a super-strong relationship with them. They’re a huge asset for us in identifying new technologies, and also a good pool for new talent.