A battery is a device that creates electrical energy by means of chemical reactions. There are two types of batteries: wet cell and dry cell. A wet cell battery operates by means of a liquid electrolyte solution, while in a dry cell battery the solution is in the form of a paste. Some wet cells can be recharged, while others are only good for a shorter period of time. Eventually, however, all such batteries become unusable and have to be replaced.
There are a number of different types of wet cell batteries, categorized as "primary" or "secondary." A primary battery can be used only until its chemicals are exhausted and cannot react with each other anymore. In contrast to this, a secondary battery can be recharged by effectively reversing the internal chemical process used to generate a charge.
Composition of Some Batteries
Most automobiles use a wet cell battery. The lead acid battery, often found in such vehicles, is a secondary battery that contains lead, lead oxide, plates, and a liquid electrolyte solution containing 65% water and 35% sulfuric acid. Some of the plates are anodes attached to the negative terminal, while the others are cathodes attached to the positive terminal.
How It Works
When a load is attached to the terminals of the wet cell battery, a chemical reaction between the lead, lead oxide, and electrolyte solution occurs. As a result of the reaction, electricity flows through the terminals to the load, and sulfuric acid is removed from the solution and bonded to the plates. When the battery is recharged by passing a reversed current through it, the bonds between the plates and the sulfuric acid are broken and the sulfuric acid returns to the liquid solution, letting it provide more electricity.
Long-Term Use and Replacement
After extended use, a wet cell battery can no longer provide sufficient electricity to the load attached to it. This happens because over time, the material in the positive plates flakes off during the normal expansion and contraction of the discharging and charging cycles. As the material flakes off, the plates become smaller and the flakes form a sediment on the bottom of the battery that eventually makes the plates short out and kills the battery completely.
A wet cell battery often dies more quickly in a hot climate because the heat causes the plates to either accumulate or lose material, and also because water evaporates from the electrolyte solution. In addition, prolonged use of the battery, excessive vibration, and overcharging can cause a battery to die faster. Once this point is reached, it can no longer be recharged and needs to be replaced.
History of Wet Cells
Batteries have been used for over a century, and archaeological evidence shows that galvanic cells may have been used 2,000 years ago. The wet cell battery was one of the first modern battery types to be developed. John Frederic Daniell created the first wet cell battery in 1836, which was superior to previous versions because it was safer and more reliable, although it could not be moved and was quite fragile. Since then, a series of improvements has produced those batteries commonly used today.