Crash Tests In The Torture Chamber For Batteries

Batteries and accumulators put in almost every technical device. In Offenbach developers test how responsive energy storage for heat or a crash - and when they become dangerous.

With ear deafening noise of the black box crashing to the floor. A massive dent arises immediately on the impact of several meters in height, is concreted into the ground because a steel pipe. The test is the brute safety of future batteries of electric vehicles.

The black box corresponds to a 150-pound electric battery, which is "wrapped" with a speed of 50 kilometers per hour around a lamppost. The test engineers raises the interesting question of whether the battery catches fire or not.

"Lithium-ion batteries with a specific cell chemistry tend to run hot, so to speak, in case of accidents. The battery then burns out on its own", explains Heiko Sattler. Only in May, an electric car maker BYD, the Chinese car that was rammed by a second vehicle, went up in flames and exploded.

Case of ten meters

Experts lead the fire back to a short circuit of lithium-ion batteries. According to an eyewitness of the participating sports car with more than 150 kilometers per hour on a highway was the road when it came to the accident in which three people lost their lives in the electric tax.

Such accidents will prevent the battery and environmental test center, the Association for Electrical, Electronic and Information Technologies (VDE) has now opened in Offenbach. "There are batteries and fuel cells of all sizes on their paces, from very, very small versions for laptops up to large systems for vehicles including trucks and buses", said Sattler, who heads the Centre of Excellence batteries and fuel cells.

The main facilities include the tower case, should be explored in, among other things, the behavior in severe mechanical damage. Here, raised to be tested batteries in up to ten meters high and then be swapped. It is precisely the circumstances that lead to inflammation, are of great interest. Therefore maintains a high speed camera records every second and provides engineers with a detailed analysis of the drop tests.

15 models of German manufacturers in the pipeline

One thing is certain: Once it is burning, is to remove very, very difficult. "Then you can really only wait until the fire has burned out", says expert saddler. That should be for the road transport of the future but not an option.

By 2020, it is still the plan of the federal government to put one million electric vehicles on Germany's rolling roads - and by 2025 six million. As to the eligibility criteria for electric vehicles will be significantly tightened to ensure secure e-mobility.

Even though today just lose 4500 electric car in traffic, the policy remains optimistic: "There are 15 models of German manufacturers in the pipeline", Rainer Bomba, State Secretary, Federal Ministry of Transport says. The benches in the test lab can even truck batteries up to 400 kilograms in weight and dimensions of 1.2 by 1.2 meters take a side. The power packs can be customized with defined forces crushed or destroyed by the intrusion of a metal mandrel.

Dust can be electrically conductive

"Not only the safety but also the long-term stability of traction batteries is an important issue", said Wilfried Jäger, Chairman of the Board of the VDE Testing and Certification Institute. Special test structures allow us to answer any questions that determine the lifespan of the battery.

For example, the power package is adequately protected against the ingress of dust or spray? "Dust is tricky, in conjunction with moisture, it can even be electrically conductive and cause leakage currents", says an expert saddler. Use is made of talc, Portland cement and Arizona dust, the dust is considered the finest in the world and is procured from the United States.

Keep the plastic materials used also by prolonged exposure to UV radiation? Corrosion of components in a high salt and moisture content of the air, as he preferred in the winter after the use of road salt often occurs? In special environmental chambers, the acid rain can also perform as Sprühtests adjust with salt mist. Rapid changes in temperature at 18 degrees Celsius per minute are possible as well as a water pressure of 100 bar.

Potholes can swing batteries

If the battery still start at 70 degrees Celsius? What effect does a thermal shock of up to 24 degrees per minute to the fatigue? Many questions are already acute, others will turn out until the regular operation of the new test center.

An important factor is the mechanical stresses that occur in the vehicle due to poor road conditions. Potholes of all types can be simulated in a large test stand.

The "specimens" are subjected to forces up to 120 kN, equivalent to twelve tons. In addition, the direction of the load can change in a split second. As a further hardening of the entire test stand can be extremely air-conditioned - that is, for example, determine what impact a dirt road under arctic conditions on batteries.

Loading and unloading important

It is also important, such as electrochemical energy storage will change over time - depending on how fast and how often they are loaded and unloaded. "Most of the testing facilities are therefore designed so that the battery during the test charge and can be discharged. This can also study the interaction of aging battery with other factors such as temperature or humidity", says Hunter. So-called Zyklisierer load and unload the batteries discharged to a freely programmable rhythm with voltages up to 1000V and currents up to 800 amps.

Has claimed the new test lab, the construction of around 9.6 million euros, the car manufacturers is available as well as suppliers, research institutes and government agencies. "We are a network of experts offer in the fields of science, standards, testing and certification, in addition, we have 120 years of experience on the subject of electrical safety - these skills, we now want to use for the subject Elektromobi8lität" promises Hans Heinz Zimmer, Chairman of the VDE.

Carmakers are interested in cooperation

The response to this offer is great. Many companies and institutions are interested in working together: "The tasks related to the electric vehicles are so diverse that we are dependent on efficient and competent partner", says about Ricky Hudi, Head of the Department of Electrical / electronics at Audi.

The success of electric vehicles will depend not least on how sure batteries are in use on the street actually. Accidents in Shenzhen may not happen in this country.