An automotive battery is one of the most well-known and most recognizable car parts to most people.
It makes sense that things like dim headlights, pressing the gas pedal while starting, and battery corrosion would be sure signs that the battery is bad. However, this is only true to an extent since most signs and symptoms of a bad battery are more telling of a charging system problem than a bad and/or dead battery. That being said, a bad battery is much simpler to diagnose and replace than many realize.
What Is Car Battery?
A car battery the device in a car – usually located under the hood, under one of the front seats, or in the trunk – that produces power via a lead-acid reaction. Small lead plates within the battery are plunged into sulfuric acid which creates a chemical reaction. The result is the production of ions and lead sulfate. Upon reacting with another plate, electrons are produced, creating the power produced by the battery.
Common Signs & Symptoms of a Bad Battery
If your car can start without any additional drama than normal, the problem is more likely associated with the charging system. Batteries are vital in the initial starting of a vehicle, but the alternator and other charging system components recharge the battery and help power other electronic accessories while the engine is running.
Because of this, there are only a few telltale signs that the battery itself is the issue. More likely there is an issue causing the charging system to fail to maintain the energy needs of the car. There are several straightforward, and not quite as straightforward signs you have a bad battery.
Advanced Age
Just because a battery is “older” does not mean it needs to be replaced after a specific time. Batteries can last anywhere from two to five years, but if the battery is still functioning normally after a few years, it is not bad until it stops functioning.
Of course, the chances of having it go dead increase with time, but battery load testing is always an option if you are worried. This can be done at most automotive retail stores for free, and load testers are quite cheap if you want to buy one for at-home use.
Extended Cranking Time
Because a battery has so much to do with the starting of your vehicle, extended cranking time is one of the more obvious signs that a battery is starting to go bad. Load testing is still the best way to ensure that it is a battery issue as opposed to the starter or something else.
Clicking Noise When Starting
A clicking noise exhibited at startup could be another sign that the battery is not producing the power necessary at startup. Chances are good that extended cranking times will precede these types of noises, and a bad starter will also produce a clicking noise.
Load testing the battery is the common theme when diagnosing a battery issue, and differentiating a battery issue from a bad starter is the first step in confirming what is truly happening.
Battery Corrosion
Battery corrosion occurs when some amount of the contents of the battery are leaked and react with the metal on the battery terminals. It can be cleaned off and should be when it happens, but ultimately, it signals potential battery sealing problems. Some batteries have a sealed design that aims to prevent this from happening.
Frequent Jump Starts
Similar to long cranking times, frequent jump starts are another more pointed sign that you have a bad battery since it has to do more with starting the vehicle than maintaining a charge. This is also another common predecessor to the notorious clicking noise when a battery can fully support engine starting.
Lights Are Left On Overnight
Many modern vehicles either automatically shut off a vehicle’s lights when the engine is turned off, or they are designed to only stay on for a short amount of time afterward. In vehicles that do not have this feature, accidentally leaving the lights or radio on can drain the battery.
Just because this happens does not always mean the battery is automatically dead. It could be completely fine, but attempting to start the car will be a good indicator as to whether or not the battery was affected.
Most modern vehicles have electronic sensors and other passive systems that use a small amount of power while the vehicle is off. It is common that walking out to a vehicle with a dead battery a day after everything was fine means that these systems could be drawing too much power, resulting in a dead battery. It is important to have both the battery and electrical draw checked when this occurs.
Leaking or Bloated Battery
A battery that is visibly leaking or deformed is a definite sign that the battery is bad. A leaking battery can also be a general hazard because of its contents, but many modern batteries are designed to prevent both from happening as much as possible.
Everything is Dead
Walking out to a vehicle in which nothing works, including the keyless remote, interior lighting, exterior lighting, and other systems, is the most obvious sign that your battery has gone bad. Usually, this does not happen instantaneously and there are other signs and symptoms exhibited first. This commonly happens when you let your vehicle sit for several days at a time.
Other Miscellaneous Signs
Several other things like dim headlights, backfiring, the check engine light and unusual smells are listed as common bad battery symptoms, but these issues are either so broad or so indirectly related to a bad battery that they are rarely bad battery issues. With that being said, they certainly can be battery-related signs, but they should be considered in tangent with other more straightforward battery signs.
What is the Expected Lifetime of a Battery?
Depending on the brand, type, and expected normal use of the battery, it can normally last anywhere from two to seven years. Most modern high-end batteries are expected to last for an average of five years while less expensive, less technologically advanced batteries will normally last for two or three years.
Batteries that do not meet those expectations are those that are inadequate for the power needs of a vehicle or those that have been on the shelf for too long. Even though batteries are primarily used to start a car, vehicles with many accessories can cause the charging system to fail to keep up with energy demands. Even if the charging system is working perfectly, too much energy draw is a possibility.
How Much Does Battery Cost to Replace?
Because batteries are generally easy to replace, doing it yourself will only require the buying of the battery itself. It could be just as easy to have the battery replaced with other services are done to the vehicle, and in this case, labor will add a few extra dollars to the cost of everything else.
Depending on the size of the vehicle and its electronic needs, a battery can cost as little as $50. Some high-end batteries can cost around $250, but unless your vehicle has special needs or you want a presumably incredible battery, this is the exception rather than the rule.
It is also sometimes possible to recharge a battery without getting a replacement. This will usually cost less than replacing the battery, and at-home battery chargers are easy to find in automotive retail locations or through online shopping.
Learn More: How Long Does it Take to Charge a Dead Car Battery?
Final Thoughts
Despite batteries being one of the better-known vehicle components, many people assume that it does more than it actually does. It is still an important component that helps power the electronics in your vehicle, but there are fewer direct signs and symptoms of a bad battery than many realize. Things like slow cranking, frequent jump starts, and a totally dead vehicle are much better signs of a bad battery than dim lighting, backfiring, check engine light illumination, and bad odors.
