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Bruel and Kjaer has supplied an LDS vibration test system for electric vehicle preproduction qualification and functional test of a T-shaped battery assembly at a General Motors (GM) battery test lab.

GM’s 3,000m2 lab at the Alternate Energy Center, Warren Technical Center, Michigan, US, tests battery cells and packs for the Chevrolet Volt electric vehicle, which has a ‘Voltec’ extended range propulsion system.

The weight of the battery unit for this vehicle can exceed 190kg.

Tony Cullen has been involved with the GM-Volt battery vibration test lab since it came online in the second quarter of last year.

Today, he is a lead test engineer for the vibration room in the laboratory.

The battery test lab has seven lead test engineers, four of whom are dedicated to battery testing, and one each for cell, vibration and abuse testing.

Cullen said: ‘The Volt uses kinetic energy to charge the lithium-ion batteries.

‘A standard Volt in urban driving conditions will do 40 miles on a full battery charge.

‘Once the energy in the battery reaches a specific level, the onboard 1.4-litre gasoline engine takes over and powers a generator to supplement the battery.

‘The engine and generator now supply power for the vehicle and everything is automatically controlled by sophisticated onboard computer systems.

‘The main purpose of the vibration lab is to test the battery’s durability by simulating its lifecycle,’ he added.

The targeted lifetime of the battery is 10 years.

In addition to vibration, various other tests such as thermal and mechanical fatigue are carried out.

The random vibration test lasts for 48 hours, which means 48 hours of random vibration input and shock pulses.

The data to power the shaker is acquired from a Volt on the GM proving ground.

‘They test the battery in the X, Y and Z axes – one at a time – and each axis test takes 16 hours,’ said Cullen.

Vibration testing also takes place in a climatic chamber where temperature and humidity are strictly and closely controlled.

The environment in this chamber can range from -30C to +78C, and each 16-hour axis test is carried out under controlled temperature and humidity conditions.

To meet GM’s testing demands, the system used had to be high performing and easily adaptable to several test demands on large heavy payloads in multiple axes.

The LDS vibration test system fulfils GM’s requirements for a heavy-duty system, able to perform accelerated durability tests simulating the lifetime of the car.

This includes several days of continuous testing at very high vibration levels and extreme temperatures.

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