Chloride silent Power Limited (CSPL) has developed a number of laboratory and field test batteries in support of its sodium sulfur development program. The most demanding of these test batteries is being developed for the Ford ETX-II electric vehicle, under a three year contract from the US Department of Energy. A major milestone of this program is to build and test an Intermediate Deliverable (ID) battery which is a fully representative section of the final battery. This will allow the performance predictions to be evaluated using an operational battery before the final battery is built and delivered. The performance predictions for the battery have been made and are described in the paper. The Intermediate Deliverable Battery, representing one third of the full battery both electrically and thermally, has now been built and preliminary test results are available.