Lead-acid batteries in micro-hybrid vehicles

More and more vehicles hit the European automotive market, which comprise some type of micro-hybrid functionality to improve fuel efficiency and reduce emissions. Most carmakers already offer at least one of their vehicles with an optional engine start/stop system, while some other models are sold with micro-hybrid functions implemented by default.But these car concepts show a wide variety in detail—the term “micro-hybrid” may mean a completely different functionality in one vehicle model compared to another. Accordingly, also the battery technologies are not the same. There is a wide variety of batteries from standard flooded and enhanced flooded to AGM which all are claimed to be “best choice” for micro-hybrid applications.A technical comparison of micro-hybrid cars available on the European market has been performed. Different classes of cars with different characteristics have been identified. Depending on the scope and characteristics of micro-hybrid functions, as well as on operational strategies implemented by the vehicle makers, the battery operating duties differ significantly between these classes of vehicles.Additional laboratory investigations have been carried out to develop an understanding of effects observed in batteries operated in micro-hybrid vehicles pursuing different strategies, to identify limitations for applications of different battery technologies.

Research highlights▶ Overview of functions of micro-hybrid vehicles and battery duty. ▶ Vehicle investigation of micro-hybrid vehicles available in Europe from 2006 to 2010: different functionality streams observed. ▶ Laboratory test “dynamic pulse cycling” (DPC) for simulation of micro-hybrid battery duty: test description and results. ▶ Influence of acid stratification on flooded batteries. ▶ Effects of rest phases on stratified flooded batteries: description of processes and results of laboratory and real-life tests.