An Introduction to Car Batteries and Alternators

A car needs a lot of electricity to transport you safely from point A to point B. On top of powering your engine, you need electricity for lights, charging ports and your radio. An old pack of Double A batteries simply
won’t cut it.

That’s why your vehicle has a special rechargeable battery along with a system for keeping it fully charged. This electrical system, known as an alternator, is one of the most important aspects that make up your vehicle.

In terms of long-term value, it’s in our best interest to keep our car’s electrical system in good condition. Having a reliable vehicle reduces the chance of future breakdowns and repairs, which translates to peace of mind. Your vehicle’s battery and alternator should be professionally checked during service appointments.

We’ve created this article to educate you about batteries, alternators, charging systems and the role they play in your vehicle.

Car Batteries

Batteries are designed to use a large amount of current for only a few seconds. Just long enough to get your engine started. The alternator then takes over to power the rest of your vehicle.

Most car batteries rely on lead-acid chemical reactions to get things moving. A new battery can cost you anywhere from $100 to $250 depending on your vehicle’s specific needs.

The lifetime of a battery is typically 3-6 years. Their lifetime mostly depends on how often you drive and how well they’re maintained. They can have a far shorter lifetime if they’re treated poorly.

There are a couple things you should be aware of for maintenance. Listening to the radio without the engine running or leaving lights on overnight, can permanently damage the battery, preventing it from fully recharging. If it’s damaged enough it won’t ever produce enough power to start your vehicle.

Another point to mention is that your vehicle should be run regularly. Generally, 3-4 weeks is the maximum amount of time a car should be left dormant.

Since your car’s battery gets charged every time the engine is turned on, the battery will gradually be discharged if the car hasn’t been used for quite some time.


As we mentioned above, the battery is only used for getting your car started. When the car is running, the alternator generates energy to feed the electrical system and charge the battery at the same time. It’s like a mini generator that converts mechanical energy into electrical energy.

The alternator consists of a voltage regulator and three main components: The stator, rotor, and diode. When the battery initially powers the car, the alternator belt, or V-belt, spins the pulley on the alternator, causing the rotor inside the alternator to spin very quickly. This rotor, which is basically a magnet or group of magnets, is situated inside a nest of copper wires, which are called the stator.

When the alternator pulley is rotated, alternating current (AC) passes through a magnetic field and an electrical current is generated. Without getting more technical, this electric current is what powers your vehicle. Alternators are complex parts, which explains why they can be expensive to replace.

When a car alternator is going bad, drivers will notice a reduced capacity for electrical use. A common sign is dim headlights. These clues don’t last long, because a partially charged battery usually has enough power to operate things like headlights and power windows, but will fail the next time you try to start the vehicle.


We hope you’ve found this article to be very informative as an introduction to car batteries and alternators. The electrical system in your vehicle is critical for reliability. It’s important to have it checked professionally during service appointments. At the very least, your electrical system should be checked every spring and fall.

Even if your battery, alternator and charging system are in great condition, we recommend keeping a pair of jumper cables in your vehicle. Receiving a quick boost from another vehicle could get you out of a tough spot and save you the cost of a tow truck.

For further information about car batteries and alternators, please contact us or visit our Batteries & Electrical Systems page.