The optimisation of grid designs for valve-regulated lead/acid batteries for hybrid electric vehicle applications

The design, construction and testing of valve-regulated lead/acid cells with grid designs optimised for high-rate partial state-of-charge cycling for hybrid electric vehicles are described. Computer modelling was used to develop the grid designs. This showed that designs with opposed tabs and terminals on the top and bottom of the cell were likely to have the best performance not only in terms of grid conductivity but also for uniformity of active material utilisation. Prototype cells were built and tested. Low rate performance was in line with the designs and the high-rate performance was substantially enhanced compared with conventional constructions. The cells were then tested to a shallow cycling regime and to a simplified hybrid electric vehicle cycle. The results showed excellent life under these conditions without the benefit of carbon or graphite additives to the negative active material that have also been shown to improve cycle life under these conditions.