AGM batteries are built using a glass mat separator which enables all the electrolytes required by the battery to be stored within the glass mat, also allowing any gasses given off during charging to be recombined into water meaning that the batteries are totally maintenance-free. The design benefits of the glass mat over conventional flooded batteries enable the battery pack to operate under higher pressure without the fear of insufficient electrolyte between the plates, leading to the step change in durability offered by AGM batteries over flooded. The quality of the glass mat is a critical item in ensuring the optimum life of the battery versus its application. This experience has been gained by Metro from over 20 years of experience in the field using this technology. The automotive application battery designs are balanced with greater high-rate starting performance and cycle life for the increased service/technological requirements of modern vehicle designs.