New possibilities for safe battery testing

As the number of batteries in our society increases, so does the need for knowledge about fire risks and safety. Therefore, DBI has developed new test facilities that make it possible to conduct fire tests of batteries under safe and controlled conditions.

We now have batteries everywhere: in electric cars, electric bicycles, electric scooters, and phones – to name just a few battery-powered products.

The risk of fire in lithium batteries is generally low, but if a fire does occur, it can be difficult to extinguish, tends to re-ignite, and in some cases may even lead to explosions. This is due to so-called ’thermal runaway’, where a self-reinforcing heating process develops inside the battery. Battery safety is therefore an issue we should take seriously and examine more closely.

”Many batteries are generally safe enough, but unfortunately not all of them are. So as the number of batteries increases, so does the need for greater safety and more knowledge in the field,” says Robert Firkic, head of DBI’s Advanced Fire Testing department, and continues:

”Battery safety is still in its early stages and can be somewhat of a jungle to navigate. There is a lack of clear and comprehensive standards for batteries, unlike many other areas. Work is underway to develop harmonized European standards, but there is still a long way to go before they are available.”

Tests in a controlled environment

DBI has therefore taken matters into its own hands and built a new test facility that makes it possible to test batteries in a safe and controlled environment.

”We perform various ad hoc tests on a small scale. The tests can involve both well known and newly developed battery types, for example battery modules for electric cars, where we do not test the entire battery pack but only a smaller part of it. These are not always pass/fail tests, but rather opportunities to experiment in order to gain more knowledge about risks, limitations, and possibilities,” says Robert Firkic, and elaborates:

”The results of our tests can provide valuable insight into product properties, just as building owners and shipping companies can gain knowledge about fire risks associated with the use of batteries in buildings or on ferries. This can, for example, be relevant when installing batteries next to buildings, transporting electric cars on ferries, or assessing fire spread between electric vehicles.”

The tests are carried out in a specially built container – the so-called MOBAT (Mobile Battery fire testing unit) – developed specifically for this purpose. MOBAT is equipped with a test chamber containing a fire suppression tank and the ability to measure different gas compositions. It also includes a control room with video surveillance and measuring instruments connected to DBI’s facade test hall measurement and data systems. The test chamber and control room are separated by an explosion-proof wall and have pressure relief openings in case of an explosion. In addition, MOBAT is equipped with a ventilation and smoke purification system.

Both explosion and extinguishing tests

”Some tests are designed to trigger a failure in the battery so that it causes a fire and possibly an explosion. In these tests, we shut off ventilation and fill the test chamber with gases. Other tests involve exposing the battery to open flames and examining when it ignites, how it contributes to the fire, and how it can be cooled and extinguished again,” explains Iben Hansen-Bruhn, PhD in chemistry, adding:

”We can also carry out tests to collect data related to extinguishing battery modules. In such tests, extinguishing water is collected in a tank in the test chamber.”

”When testing batteries that can behave unpredictably and explosively, it is crucial to be able to conduct tests under controlled conditions. However, the most unique aspect of our tests is actually our methods, which are based on extensive experience and strong competencies in testing,” says Robert Firkic.

Extinguishing with seawater and brine water

A recent example of a test requiring special expertise is an extinguishing test that DBI recently conducted for the Faroese ferry company Skansi Offshore.

”Our client wants to expand the use of brine water systems on ferries where it may be necessary to extinguish an electric vehicle fire. Brine water has a significantly higher salt content than seawater and therefore only freezes at around minus 20 degrees Celsius. So we conducted tests of extinguishing battery modules in both seawater and brine water – partly to compare extinguishing speed and measure water temperature differences, and partly to examine the condition of the batteries after extinguishing,” says Robert Firkic and continues:

”We set up five identical battery modules, each consisting of six battery cells. In each of the five tests, we triggered thermal runaway. Two of the modules were extinguished in seawater, while the remaining three were extinguished in brine water.”

”The challenging part was ensuring completely identical conditions during heating, igniting all battery cells simultaneously, and inducing thermal runaway. It may sound simple, but it’s difficult to control in practice, so we are very satisfied with the results,” says Robert Firkic.

Additional testing possibilities

All tests in DBI’s MOBAT container are conducted on a small scale but can form the basis for subsequent testing of larger systems.

Since MOBAT is mobile, it is also possible to move the facility to another location if testing is preferred there instead of at DBI.

MOBAT (Mobile Battery fire testing unit)

DBI’s MOBAT is a specially built container designed for explosion and extinguishing tests of, among other things, battery modules. In MOBAT, fire tests are conducted on both well known and newly developed battery types. All tests are ad hoc and small-scale.

MOBAT is equipped with a test chamber, a control room with measuring instruments and cameras, and a ventilation and smoke purification system. The test chamber includes a fire suppression tank and the ability to measure different gas compositions.

MOBAT is mobile and can be transported to any location where testing is desired.