Automotive 101: Everything You Need to Know About Your Car's Battery

A car's battery powers everything from the fuel pump to the radio and is very important

Automotive 101: The Battery is the Life Force of Your Vehicle
Image: Pixabay
July 10, 2018

You've probably stumbled across this article because you suspect a problem with your car's battery or because your car's battery is causing you headaches. The battery is the life force of your car. Without it, you would not be able to have power to do anything from starting the engine in subzero temperatures to cruising down the highway on a sunny day. Sure, the engine does a lot of work and it should get credit for what it does. But without the battery, your engine would just be a several thousand dollar paperweight.

The battery, not the alternator, powers the car

Many people think that the alternator powers the car, but it's the battery that provides the juice for your electronics.

Your vehicle needs a steady and stable source of power. Because of fluctuations in your power needs, such as turning on your heater or headlights, the amount of power needed varies from one moment to the next. Your alternator may not be able to put out the required power as it's output is proportional to engine speed; that's why your electronics pull power from the battery, which has a lot of power ready for your needs. During periods of high power usage, your battery will slowly discharge, even though the alternator is providing it with power. During times of low power usage, your alternator will slowly recharge the battery.

Overloading and discharging a battery can weaken and damage it

Vehicles that operate a lot of accessories, is operated infrequently, or that makes frequent short trips may not have enough time to fully recharge the battery. These vehicles may have a dead battery every few weeks. A battery that frequently discharges won't last as long as a battery operated under normal conditions and can even cause the alternator to have a shortened lifespan as it must operate under a high load.

How long will my car's battery last?

There's really no easy way to answer that question. Older batteries don't perform as well as newer batteries and thus won't last as long as a brand new one. But even a new battery won't last forever. Batteries typically last anywhere from three to five years on average, but this is only an average. Some last much shorter and some last much longer. It all depends upon the type of battery, the brand and how well you care for it. Just like the rest of your car, maintenance can have a big impact on battery life. Make sure to follow all recommended maintenance on your battery, such as ensuring adequate fluid levels and keeping the terminals clean.

Battery Warranties: Batteries Installed by the Car Manufacturer

If you have a battery that is covered under your car manufacturer's warranty, you likely aren't getting as much peace of mind as someone who buys and installs a battery outright. Despite most vehicles being covered for three years or 36,000 miles from the date of purchase under the 'bumper-to-bumper' warranty, batteries are consumable items and typically have a warranty of only two years or 24,000 miles depending upon the vehicle manufacturer. After that time, you may have a pro-rated warranty or no warranty at all. Check your car's warranty manual to determine the warranty coverage for your battery. If you suspect a battery problem and are still covered by warranty, get your car checked out before your warranty expires.

Battery Warranties: Batteries Installed by You or a Third Party

There are big differences in the warranties from one battery to the next. One of the biggest differences is cost, but it's easy to simplify matters if you think of the cost as the price of the battery plus the cost of the battery warranty.

You may see some more expensive batteries listed as having a five year warranty over the standard two year warranty on another of the same brand. You may see confusing terminology, such as 'silver' or 'gold,' or you may have a part counter employee trying to get you to upgrade. The basic difference here, assuming the batteries are identical, is that you're paying a little extra money now to have an extended warranty on that battery. But is that longer warranty worth the extra money upfront? Usually, extended warranties are not worth it and we typically recommend against extended warranties. Batteries are no different.

Regardless of the length of the warranty you purchase, batteries are usually prorated after a few years anyway. Let's take a hypothetical five year warranty. The first two years may be 100% replacement, but for each month past two years up until five years, the amount the manufacturer will reimburse you for a failed battery decreases each month. If your battery was $100 and your battery fails a month before the five year warranty expires, you might be shelling out $97 with the manufacturer contributing only $3. If you paid an extra $20 for that extended warranty, you're losing money. A longer warranty doesn't mean that the battery is any better, will perform better or last longer.

In any case, the service center or parts department will have to verify your warranty if you need to make a claim. If records aren't on file, you may have to provide your receipt, which can get lost after a few years. Make sure you keep your receipt in a place you can easily find it. Don't rely on the plastic pockets sometimes attached to the battery. What happens if the battery leaks acid? That's right. Your receipt is gone. Keep your receipt in your car and take a good quality photo. In time, receipts seem to fade and become illegible.

I Suspect a Problem with my car's battery

If you suspect that your battery might be going the way of the dinosaur, don't just replace it. Have it tested! Many auto parts stores offer free battery testing, so it's easy to get your battery tested every few months when popping in for a set of wiper blades.

A word of caution if you decide to have your battery tested by a parts store: some store associates work on commission and are dishonest. When testing your battery, make sure the associate inputs the correct Cold Cranking Amps (CCA) number from your battery label into the tester. If the associate accidentally inputs a baseline number too high, your battery will fail the test, even if it is perfectly fine. If you doubt the test, take it somewhere else! You may even find out that your battery is fine but another component is either drawing too much power or your system isn't generating enough power. Just remember that parts store associates are not mechanics and don't have the mechanical know-how to properly diagnose a problem. If they were mechanics, they wouldn't be working at a parts store! If you think you have a problem with your car beyond a simple battery replacement, it's time to visit the shop.

Signs to Have Your Battery Checked

Engine Cranks, But Doesn't Start

Most people reach for jumper cables when the car cranks but doesn't start. In many cases, the battery has discharged and isn't able to start the car. But that's not always the case. If the car seems to have a lot of juice and can turn the engine over rapidly, the battery may not be the culprit.

Three things are needed to start a car: power, air and fuel. If the car doesn't start, it's not getting enough of one of these items. You can always give the horn a quick press to see if it sounds good and loud. If it's weak or doesn't work at all, you aren't getting enough or any power from the battery. If the battery has died, run the car for a sufficient enough time to recharge the battery or recharge it with a charging device. You may have to drive on the highway to get enough of a charge to start it again later. Definitely have your battery and charging system checked at this point as a discharged battery can soon fail.

No Power to the Vehicle, Such as Lights, Horn, Etc

As mentioned in the previous section, a weak or inoperative horn indicates that not enough power is making it to the vehicle. But what if you are already driving and suspect you have a weak battery? Are your headlights flickering or getting dim? Is your radio turning itself off and on again? Does it feel as if you are going to stall? There is a good chance that you aren't getting enough power! If you suspect that you aren't getting enough power, you should immediately turn off any accessories you don't need in order to conserve enough power to get your car to a safe place. You'll have to have your battery and charging system tested. You might even be pleased to learn that your battery tests fine but has a buildup of corrosion on the terminals prevent power from getting to where it needs to go.

Hard Starting in Cold Weather

When the weather gets colder, your battery has to work much harder to start the car. Cold weather reduces conductivity, which means not as much power is making it through the wires and cables as would normally happen in the summer. If you are experiencing hard starts when it is cold out that seem to improve when it gets warmer, you definitely need to test the system. Make sure that the Cold Cranking Amps (CCA) rating on your battery is sized appropriately for your vehicle.

Check Engine Light

The check engine light usually illuminates when there's a problem with a particular component in your car. But if the battery isn't providing enough power to these components, these components might malfunction. Your mechanic should always check the battery and charging system whenever you have any malfunction lights illuminated.

Low Fluid Level

The battery's fluid helps it maintain charge. If the fluid level dips too low, the battery can become damaged or may be weak. You can check the fluid level by removing one of the caps. Add only distilled water if the level is low and have the system tested. A low fluid level could mean that your battery is overheating. A sealed battery will never need to be checked. Many batteries produced today are sealed, but some inexpensive batteries are not.

Swollen Battery

If the battery case is swollen or bulging, it's probably bad. It should be tested and most likely replaced. Excessive heat can also be the cause, which shortens the battery's lifespan.

Leaking Battery

If a sealed battery is leaking, it must be replaced. An unsealed battery probably needs to be replaced, but it might also be overheating and some of the fluid can be spilling out.