Recent progresses in the technology of the Ni-Zn batteries have a direct influence on the improvement of the performance of hybrid electric vehicles. This paper evaluates the progresses of these batteries in particular for application on hybrid light vehicles. They assess the performance of 12 V secondary cell elements, illustrate the results obtained on 6 12 V, 30Ah-C/5 Ni-Zn elements, and provide also some comparison with 2 12 V 22.5Ah-C/5 advanced lead-acid elements. The purpose is to assess the short term performances of both types of elements when employed on hybrid light electric vehicles. They present an engineering model for the Ni-Zn elements, inspired from an existing one relevant to lead-acid batteries, which permits to evaluate the available charge. For the Ni-Zn technology long term performances have also been investigated and relevant results are reported.