Figure 6. Typical construction of a tubular plate

Connector bus Active material Centering projections Porous separators Axial lead current collector End cap OPERATION AND CONSTRUCTION DOE-HDBK-1084-95 Lead-Acid Storage Batteries Batteries Page 16 Rev. 0 Figure 6. Typical construction of a tubular plate. The two most common alloys used today to harden the grid are antimony and calcium. Batteries with these types of grids are sometimes called "lead-antimony" and "lead- calcium" batteries. Tin is added to lead-calcium grids to improve cyclability. The major differences between batteries with lead-antimony and lead-calcium grids are as follows: 1. Lead-antimony batteries can be deep cycled more times than lead- calcium batteries. 2. Flooded lead-antimony batteries require more frequent maintenance as they near end-of-life since they use an increasing amount of water and require periodic equalization charges. 3. Lead-calcium batteries have lower self-discharge rates as shown in Figure 7 and therefore, will draw less current while on float charge than lead-antimony batteries. 4. Lead-calcium positive plates may grow in length and width because of grid oxidation at the grain boundaries. This oxidation is usually caused