It is easy to picture a car battery as a small, rectangular box that is filled with a liquid and has two metal rods sticking out of its top cover. Interestingly, the history of the car battery shows that this basic concept has not evolved much over the years. In fact, this general design can be applied to most types of past and present batteries.
In the 1960’s, a spill-proof design was created out of a similar housing. Instead of a liquid solution of sulfuric acid, however, it contained a gel solution that was made by mixing the liquid with silica. The gel was easier to handle and less prone to being spilled, but it contained the drawback of being unable to hold a charge for as long as a standard liquid-filled battery.
The modern car battery is often held in a case which is made of an opaque plastic. The user cannot see inside, but the basic design has remained the same. Metal plates are placed in a solution of roughly 35% sulfuric acid and 65% water. Often, one 12-volt cell is enough to start a car, but sometimes a two batteries are necessary to start larger vehicles such as over-the-road trucks.
On the smaller end of things, motorcycle batteries and golf cart batteries follow a similar pattern. They are contained in a plastic case with metal plates and an acidic solution. The voltage is often the same for these batteries, as well. Car batteries can produce more amps, but the car and motorcycle battery voltage is usually 12 volts.
Car battery prices can vary between manufacturers. Some cutting-edge designs claim to deliver better cold weather performance, where others claim to last longer or stay better protected from the violent movements of off-road driving.
Lastly, a vehicle can act as its own car battery charger. After an engine is started, a current is generated from the alternator which is then fed back into the battery. A reversal of current takes place and the battery gains what it has lost. Trickle-chargers are also available, where a battery can be taken out of the car and hooked up to a 120V outlet. The number of times a battery can be recharged is dependent on its size and quality of materials. No battery lasts forever, but modern cells can work well for several years before they need to be replaced.