A LOOK INSIDE THE BOX
Grid Manufacture (lead-calcium-alloy)
Active Material Pasting (lead-oxide)
Individual Plate Finishing
Completed Cell Assembly Alternate +/- plates
3DX grid (Expanded Metal)
Negative plate example sponge lead (Pb)
Framed grid Positive plate example lead dioxide (PbO2)
Absorbent Glass Mat (AGM)
The battery is one of the most important car components, yet what is inside the box is rarely seen. By looking at how a lead-acid battery is made, we can understand the differences between various technologies and pick the right battery for our needs.
Lead Plates No other material, synthetic or natural, comes close to the unique properties of lead, which has formed the essential building block of rechargeable batteries for the past 150 years. It is also very easy and economically viable to recycle again and again. To give the material the mechanical strength required for high-quality batteries, battery manufacturers such as Exide use a lead-calcium alloy for both positive and negative grids, so-called calcium-calcium , essential for maintenance-free batteries.
Traditional grids are gravity cast, a method of placing molten lead alloy into a mould before leaving it to solidify. This technique is still relevant for the thicker plates used in deep- cycle AGM and GEL batteries. In more recent years, starter batteries are using new thinner grids, which create a larger surface area without increasing the size of the battery. This provides more starting energy.
New manufacturing processes have emerged that rely on a rolled lead alloy strip. One method is where punched grids are obtained by pressing out metal scrap that is later recovered by re-smelting. Exide was one of the first European producers
to refine an alternative method with its 3DX Grid (Expanded Metal), where the lead alloy is slit and then very precisely stretched. The re-processing of punched-out scrap is eliminated and the reinforced 3D diamond mesh ensures that the active mass stays fixed on the mesh, resulting in better electrical performance and longer lifespan.
Cell Assembly Grids are then pasted with the active materials using lead-oxide powder as the main ingredient. The positive and negative plates, now referred to as electrodes, are assembled in alternating sequence, set apart by microporous separators to form an individual cell. The separator prevents the plates from touching and causing a short circuit, yet still allows ions to freely flow back and forth. After charging, the positive plate becomes reddish-brown, indicating the presence of lead dioxide (PbO2), while the negative plate turns into grey sponge lead (Pb).
LEAD THE ESSENTIAL BUILDING BLOCK OF RECHARGEABLE BATTERIES FOR THE PAST 150 YEARS