Enhanced test methods to characterise automotive battery cells

This article evaluates the methods to characterise the behaviour of lithium ion cells of several chemistries and a nickel metal hydride cell for automotive applications like (plug-in) hybrid vehicles and battery electric vehicles. Although existing characterisation test methods are used, it was also indicated to combine test methods in order to speed up the test time and to create an improved comparability of the test results. Also, the existing capacity tests ignore that cells can be charged at several current rates. However, this is of interest for, e.g. fast charging and regenerative braking. Tests for high power and high energy application have been integrated in the enhanced method. The article explains the rationale to ameliorate the test methods. The test plan should make it possible to make an initial division in a group of cells purchased from several suppliers.

► Discussion of the six main international (draft) standards to characterise battery cells.
► Confrontation of the test methods with the four intended vehicle applications, ranging from hybrid electric busses up to battery electric cars.
► The new battery methodology covers five characterisation tests.
► The tests can be used both for lithium-ion and nickel metal hydride cells provided that the current rates are divided by 5 for the last one.
► The test plan should make it possible to make an initial division in a group of cells purchased from several suppliers.