Lead acid battery construction

Lead acid battery construction consists of the following elements or components

1.       Battery case

2.       Battery terminals

3.       Negative plates

4.       Positive plates

5.       Insulators or separators

6.       Battery posts or terminals

7.       Electrolyte H2SO4

There are two categories of commercial batteries. Three year and Five year. The main difference between them is the materials used in their manufacturing. The material means the active material used to construct battery plate. These materials are reacting with electrolyte and produce electricity. Both positive and negative plates have different active materials. The quality and price varies for such materials. Also the manufacturing quality varies. Cheap plates are manufactures with ordinary process by common people whereas good quality plates are made by high pressure hydraulic machines with specialized procedure by specialists. Both low quality and high quality plates have different life span and different performance and efficiency.

Lead acid battery construction

Plate is basically grid plate like thick mesh made of lead alloy. In the plate lead material 6 to 7% antimony is mixes to provide good strength to grid. Plates have tabs attached to them so that tabs can be welded latter with connection terminals. The plate has vertical and horizontal grid bars which intersect each other at right angle.

The active material is powder lead oxide, material expander and acid H2SO4. This material is made like a thick past and pressed with pressure in plate grids. After drying a forming charge is provided to the plates. The forming charge makes the plate polarity negative or positive.

The forming charge is provided in the battery electrolyte same like charging a battery. When providing forming charge the positive plate active material is converted into lead peroxide. The negative plate active material is converted into spongy lead.

The positive and negative plates are fixed alternately and welded each type of plates together on one side. This arrangement is known as a cell. Usually 7 to 13 plates of each polarity are connected together to make a cell. Both plates are insulated or isolates by special type of insulators known as plate separators. These separators are special insulating material which is micro porous material. These insulators are separators hold and pass battery electrolyte. These separators are effectively providing battery electrolyte to the battery plates during battery function as they are locates close enough to the plates.

The cell is completed by welding all positive plates together on one side and all negative plates on the other side. They don’t touch to each others at any point. If the touch to each other, a short circuit could create and the cell will be referred as a shorted cell. Six cells are normally connected in series to make a 12v automotive battery. Each cell has 2.1v level and current depend upon the area and number of plates. So all cells in series make a voltage level of 12.6v.

Battery case is made of ebonite, polypropylene, plastic or any other hard rubber materials. Battery case should be able to withstand mechanical stress and vibration in the vehicle during its running. Also the battery case should be inert with battery electrolyte and should not react with electrolyte. Battery case is separating and isolating each cell from the adjacent cell electrically and physically. It should provide air tight sealing between the cells. Battery lids are provided on the top of the battery case. These lids are threaded on the battery top. They are to be filled electrolyte once and to be filled distilled water and maintain the electrolyte periodically. These lids have vents in them. These vents are discharging gases produces inside the battery during charging process and discharging process. These vents should be kept cleaned so that they pass the gasses without any hurdle.

On the top of batter or sometimes on the sides two terminals positive and negative are provided. These terminals are used take power form the battery and provides power to the battery during charging. They are sometimes referred as battery posts. These terminals or posts are round shape lead posts which are making connections to the vehicle electrical system. They are round shape posts.

Battery electrolyte is 63% water and 37% sulfuric acid by weight. Electrolyte reacts with plates active material and produces DC power with is supplies by battery. With the use and passage of time electrolyte level depletes and reduced down. To maintain level, distilled water is added from outside. Never add acid but add only distilled water to maintain the level. Also plan drinking water should not be added as that contains minerals and salts which are harmful for battery.

Batteries when becomes older and they loose efficiency, they should be sent to manufacturer for recycling. Some people are trying to repair them by adding different chemicals and substances like Epsom salt and Coca Cola. Such actions are useless and they have no benefit. As when the battery become aged, the active material is removed from the plates and all active material is consumed so that battery will be no more serviceable and could not be made serviceable by such useless actions.