The introduction of the 42 V PowerNet imposes new performance requirements on the battery. The required performance parameters will vary dependent on the application and to what extent the power train is hybridised, with additional features such as start-stop, launch assist etc. This makes it more difficult to specify relevant laboratory test procedures. This paper reviews the vehicle electrical system developments and the impact these developments will have on the battery performance and testing requirements. Suitable test equipment from Digatron/Firing Circuits is discussed and reviewed. (C) 2003 Elsevier Science B.V. All rights reserved.