Understanding How a Battery Operates

Understanding How a Battery Operates

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.

Electricity 101
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

You May Also Like

Advanced Wheel Bearing Diagnostics

Can a bump set a wheel speed sensor code?

A fellow employee contacted me with a diagnostic conundrum recently. When he was driving to work, the ABS and ESC light would come on just a quarter-mile from his house, and a message in the driver information center told him that these critical safety systems were not available. It did not matter the time of day or the weather. 

Driveshaft, Axle and Drivetrain Noise FAQs

These are some of the frequently asked questions about driveshaft, axle and drivetrain noise.

Drivetrain: Diagnostic Test Drive

Driveshaft problems can be spotted from the moment you put the vehicle in gear to pull it into a bay.

Constant-Velocity Axle Options

Whether new or remanufactured, complete CV axle assemblies can throw you a curveball from time to time.

Transmission Valve Body Replacement

Learning how to perform drivetrain diagnostics and “in-the-car” repairs is important.

Other Posts

Manual Transmission Service

Parts that wear out and must be replaced.

CV Axles: A Look Inside A Joint

Check out these photos and take a look inside a joint.

Transmission Valve Body Replacement Tips

Here are some important things to remember when replacing the transmission valve body.

Fuel Pressure Diagnostic Service

Use a scan tool that can look at special direct fuel injection parameters and perform bidirectional tests.