In the automobile, the battery serves three main functions. First is the obvious. It supplies electrical power for the ignition system, starter, computer system and every other electrical component while the engine is not running (or any other instance when the alternator is not charging). Second, it serves as a reserve power source, should the electrical demand in the vehicle exceed that of what the alternator can produce.
Finally, it serves as a damper or stabilizer for any electrical pulses. It absorbs high voltage spikes, and fills in between moments of low voltage. That action helps to smooth out the electrical “noise” in the system. Without that electrical dampening action, delicate electronic components could be at risk of damage from electrical spikes.
Before we get in to talking about the battery, we need to cover a few basics. First, we must define some of the terms that will be used later. These terms are “Electricity,” “Amps,” “Volts” and “Resistance.”
The first term to identify is, ironically, the most difficult one; Electricity. That term actually has more than one definition. For the scope of this article, my definition will be that “electricity” is a supply of atoms with excessive electrons. Therefore, the flow of electricity is the exchange of electrons from one atom to the next. The terms “amperage” and “voltage” are used to measure that exchange. Amperage is a measurement of quantity, whereas voltage is a measurement of pressure. Some atoms are more willing to share their electrons than others. Materials that are made out of atoms that will freely pass along electrons are referred to as “conductors.” These are materials such as metal and water. Some materials are made up of atoms that don’t share their electrons as easily, like rubber, air and plastic. Those materials, for the scope of this article, are referred to as “insulators.” Conductors have a lower resistance than insulators.
Amps, volts and resistance are connected to each other in terms of effect. For illustration of this effect, picture a generic roadway. The speed limit will represent voltage. The number of vehicles on the road at the same time will represent amperage. The number of potholes on the road’s surface will represent resistance.
If you were to stand at the edge of the road and count the cars as they passed by, as long as there was a steady stream of vehicles, you would count more over a minute’s time if they all sped up, right? In most cases, if you increase the volts (speed limit), you will increase the amps (number of cars) that pass through the wire (roadway). If you add resistance (potholes), the volts (speed) and amps (quantity) will be reduced. However, there are some exceptions. Just because the cars are moving faster doesn’t mean there will always be more. They can have gaps between them. The same is true for electricity. Just because you have 12 volts, doesn’t mean there will automatically be a lot of amps available. Keep that in mind as much electrical testing depends on that knowledge. Since 12-volt car batteries all have the same “speed limit,” they are rated by CCAs. The number of amps that a battery can deliver at 70