STATE OF HEALTH DETERMINATION OF LITHIUM ION CELLS IN AND OUTSIDE THE VEHICLE

There is an enormous effort to implement safety functionality into battery systems to prevent any accidents with the poisonous and inflammable ingredients of the electrolytes and electrode materials. But not only the safety regulation for lithium ion batteries will be different in comparison to the home electronics application, also the operating strategy must be different to guaranty the required lifetime in the automotive industry up to 10-12 years. This paperwork will show an approach to get offline (on test benches) and/or online (installed inside the car) information regarding the current healthy and state inside the cell. As an approach modeling of physical effects by the help of electro impedance spectroscopy (EIS) will be applied. The test results of cells with different parameters (supplier, cell chemistry, capacity…) will be shown in this paperwork and the conclusion is derived how this could be used to compare different cells with identical attributes (aging effects, production variations) or different attributes (benchmarking).