We would like to think the VRLA battery would have an infinite life – especially if it is not being “used” (cycled) and only remains on continuous charge being maintained for eventual use. However, this is not the case. The typical VRLA battery will eventually decline in capacity and fail due to grid corrosion and drying of the electrolyte as a result of continuous overcharge. Everything else being equal, this will occur as a result of the design of the battery including plate grid thickness, oxygen recombination cycle efficiency and the quantity of reserve electrolyte. Since the grid corrosion and electrolyte during are a direct function of the float current, it is important to control the float current to that required to maintain the cell fully charged while minimizing overcharge due to excess float current.