The making of lead-acid batteries
Lead-acid batteries in the new plant of Amar Raja are manufactured with wellmaintained equipment in an automated and controlled environment. The manufacturing processes goes through about 12 stages like oxide and grid production process, pasting and curing, assembly process, formation, filling, charge-discharge process, final assembly, inspection, packing and despatch.
The process begins with the grids, which are stamped out of a continuous strip of lead. The grids are to conduct the electrical current and to provide a structure for the active material to adhere to. Then a paste is applied to both the sides of the grids, consisting of lead oxide, sulphuric acid and water. To produce negative plates, expander material is made from powdered sulphates. Then the plates are sent to the curing process in a warm temperature and humiditycontrolled environment. During this process, the crystallisation growth occurs which binds the paste to the grids.
After the positive and negative grid reaches the assembly line they are stacked alternatively (positive, negative, positive) with separators in between to prevent short circuits, but allowing electrical current flow. All the negative plates, and positive plates are connected respectively, to create a single 2-volt battery cell. The cells are then properly oriented and inserted into the battery case. The required voltage of the battery will determine the number of the 2-volt cells. They are welded together in a series.
After placing the battery cells and welding them together, the top cover is permanently heat sealed. The top cover contains the connected elements, and the terminal posts which are formed outside creating an acid tight seal. From there, the battery travels to the next station for acid filling (electrolyte) and it is given a formation charge. During the formation charging, the battery is connected to an electrical source and charged for 18 – 32 hours, depending on the battery type and size.
The company has invested in automated guided vehicles (AGVs) for loading and unloading the batteries and in an automated charge monitoring system. An automated water circulation system removes the heat generated during charging. Once fully formed, the electrolyte is drained out and the battery is filled with higher strength acid and the sealing process is completed. Following various quality checks, cleaning and labelling, the batteries are packed in boxes for despatch.
The company has invested in solar energy to power the plant. It has installed 2.7 MW roof top solar power panels, which generate 4.5 mn KWh of energy.