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4 weeks ago

How Long Does a Car Battery Last and How to Tell if It’s Bad

signs of a bad car battery

Batteries are one of the least understood elements of a car. There is no definite answer to the frequently asked question: how long does a car battery last? That is because there are a lot of different batteries and a lot of different cars. The age of a battery depends on the cell type, the electrical system of the vehicle, and how well it is taken care of. 

Generally speaking, if the car’s alternator and battery charge controller are working correctly, a lead-acid battery can last three years. A dry battery would have enough power to start the engine for five to six years.

If your battery is already beyond saving, and you want to replace it, here’s a detailed guide on Replacing a Car Battery.

Otherwise, please keep reading to learn how long a car battery lasts and the signs it gives before dying.

When is the Best Time to Replace a Car Battery? 

Batteries are mysterious; they sometimes give signs, and other times just die out of nowhere. It is common for people to park their car perfectly fine at night and find out that it won’t even crank in the morning because the battery is flat. It is good to make battery inspection a part of your Car Maintenance Checklist to avoid sudden battery failure. 

Other than that, on the question of when to replace a car battery, here are the four times when you need to replace your car’s battery. 

Signs of Electrolyte Leakage 

This is the most critical indicator that a vehicle needs a new battery right away. The electrolyte is the lifeblood of any battery. If it leaks out, the battery cannot function. However, the consequences of leaking electrolytes can be far worse than just a dead battery. 

The electrolyte is sulfuric acid (H2SO4), and it is highly corrosive. It can eat through the body and structural elements of the car very fast. Suppose you see signs of excessive rust or paint damage under the battery. In that case, you need to replace the battery even if it is working fine.

Car Takes Longer to Start

If a car is mechanically fit and in a good state, it should start within 5 seconds. If the vehicle takes more than 10 seconds to start, the most probable culprit is the battery. This is one of the most common bad car battery symptoms and should not be ignored. Please consider having the battery replaced soon in such a case. 

The Age of the Battery 

The age of a battery is the most critical consideration in deciding when is the best time to replace a car battery. Please look for it in the car’s owner’s manual if it is the stock battery or the battery’s manual if it is a replacement unit. If the battery is past the time or mileage limit, it is rated for, consider changing it and don’t wait for the signs of a dying car battery.

If the Battery Has Run Dry 

This only applies to lead-acid batteries. These batteries have an electrolyte that facilitates the chemical reaction that makes electricity. The electrolyte evaporates during the battery’s regular operation and needs to be topped off every couple thousand miles. If the battery is dry and it is not clear when (or if) it was last topped off, the battery has probably been damaged beyond repair. Please use distilled water (never use the electrolyte) to top the battery off, and consider getting a new one soon.

How to Tell if a Car Battery is Bad 

Even though a car’s battery can die without any warning sign, that is pretty rare. Generally, there are many symptoms that a battery shows before it quits. There are specific weak car battery symptoms that you can look for to change the battery in time. Some of these signs show up on their own, and others are diagnostic measures that you can use. 

Battery Warning Light 

The most obvious sign of a vehicle’s battery being bad is the battery warning light that appears in the dash. It is a red battery icon. If that light stays on while the engine is running, the battery is bad. However, some vehicles have the same indicator light for the battery and the alternator. Keep reading to differentiate the signs of a bad car battery vs. an alternator.

Car Makes Clicking Sound When Started 

Suppose a vehicle makes a clicking sound when the key is turned in the ignition but does not crank at all. In that case, this is the most significant sign of a weak or potentially dead car battery. This happens when the battery has some current in it, but not enough to turn the starter motor which typically takes very high amperes. 

The car has Trouble Starting 

As stated above, a vehicle cranking more than 10 seconds to start is one of the signs of a bad car battery. In addition to that, the car cranking weak also indicates that the battery is just about to give up.

The battery has Low Voltage 

Car batteries have a voltage of 12.6 volts. If a battery is bad, the voltage will be lower than this. Anything under 12 volts is indicative of the vehicle needing a new battery. Some cars have battery voltage gauges in them. The voltage needs to be checked when the engine is off. When the engine is running, the alternator will correct the voltage. If a vehicle is not equipped with a battery voltage meter, a multimeter can be used to check the voltage. 

Cold Cranking Amperes are Low

The cold-cranking amperes (CCA) indicates how much maximum current it can deliver while cold. The CCA rating is written on the battery. The battery must deliver 50% of the CCA for at least 15 seconds. For example, if a battery is rated for 500 CCA, it is loaded with 250A for 15 seconds. To pass the test, it needs to deliver the current while keeping the voltage above 9.6 volts during the test.

Dim Headlights with Engine Off  

Another make-shift test that can be used to test if a battery is working as it should or not is by checking the brightness of the headlamps. To do this, park the vehicle in a dark spot and turn on the high beams with the engine running. Keep the beams on and turn off the engine. If they are considerably dimmer than when the engine was running, the battery is most probably weak.

What Are the Signs of a Bad Car Battery vs. Alternator?

Even if the car battery light is on in the instrument cluster or other signs of the battery being bad are presenting themselves, it is not always the battery. The trouble can be with the alternator. The alternator is a small electricity generator driven by a belt from the engine and charges the battery. If it is not properly charging the cell, the vehicle will show typical weak car battery symptoms. 

Here are some of the signs of a bad car battery vs. alternator that can help you distinguish the problem. It is essential to pinpoint the issue because if the alternator is bad, the issues will not be solved no matter how many times you replace the battery. 

Indicator Light 

The most obvious sign of a bad alternator is a warning light in the instrument cluster. This is often in the shape of a red battery icon. If that light stays on while the engine is running, the alternator is most probably faulty. However, it can also be indicative of a defective battery. The following signs will help distinguish the problem.

Headlamps Flicker During Normal Use 

Headlamps are among some of the most energy-intensive electronics of the car. They cannot run on the battery alone for a long time and need the current from the alternator. If the alternator is bad, the headlamps can flicker, or their brightness can fluctuate while the engine is running.

Frequent Problems with Car’s Electronics 

Suppose you have problems with the car’s electronics like a malfunctioning ECU, blown headlamps, and indicator lights. In that case, it can be a sign that the alternator is not working as it should.

Fuses are Blown Often 

A bad alternator does not always produce lesser current; it can cause surges in electric output too. If that is the case, the fuses in the vehicle will keep blowing regularly. A lot of, or frequent, blown fuses with no apparent cause indicate a malfunctioning alternator.

In Conclusion 

To sum it up, a car battery typically lasts between three and six years, depending on the type of the battery and how well you take care of it. If your car battery dies and you want to replace it, you can follow this guide to replace it at home and save service costs. 

The battery is not the only part of your car that needs to be taken care of. Depending on your vehicle, make a car maintenance checklist and keep checking the car periodically. It will save you the trouble of being stranded on the side of the freeway and increase the life of your vehicle.

Frequently Asked Questions

Will a dead car battery recharge itself?

No battery can charge itself. Cars, however, have an alternator that charges the battery. If a car’s battery is dead, it needs a jump-start, and then the alternator will charge the battery. However, a discharged battery draws much current and strains the car’s alternator and the electric system. So, it is better to get it charged outside the vehicle.

What causes a car battery to die?

The most common cause of battery failure is the age of the battery. Batteries last between three and six years on average. Other than that, leaking electrolytes and over-discharging can also permanently damage a car battery. 

Does a car battery charge while driving?

Yes, the car has an alternator driven by a belt from the engine and charges the battery as you drive. Without the alternator, the battery will hardly last 20 miles.

Can a dead battery be brought back to life?

That depends on how dead the battery is. Suppose the car battery died because you left the headlamps or stereo of the car on overnight. In that case, the battery can be charged, and it will work normally. However, if the battery is old or has run without the electrolyte for too long, it cannot be fixed.

What to do if a car won’t start and the battery is good?

The first thing to check is the anti-theft or immobilizer system of the car. If that is not the issue, check the fuses to see if one of them is blown. Beyond that, there can be problems with the fuel delivery, air intake, or timing of the car. Those issues need a mechanic.

Is there any kind of car battery testing?

There are two ways of testing a battery in a vehicle. First is testing the voltage of the battery. It needs to be more than 12 volts. 12.6 is ideal, but anything above 12 is good. The second type of car battery testing is called cold cranking amperes (CCA). This is the amount of current the battery can deliver to the vehicle’s starter motor while it’s cold. These differ from battery to battery and are written on it. 

What does the car battery light on the dashboard mean?

That light can mean two things. There is either a problem with the battery or the alternator that charges it. Some cars have separate indicators for both, while some have a single light for them.