How to Know When Car Battery is Bad

How to Know When Car Battery is Bad

Like Iron Man needs his arc reactor to stay alive, your car also needs a battery to get moving. Your car battery provides the electricity needed start the engine and operate the electrical components in your vehicle.

Given its importance, an inefficient battery can be a real nuisance when you are trying to move from point A to point B. In this article, we are going to show you how to know when car battery is bad.

Battery Problems? How to Know When Car Battery Is Bad

It is always advisable to monitor the health of your car battery so your car doesn’t fail when you least expect it.

You can usually tell if your car battery is about to die by looking out for certain warnings. The most notable signs your car battery is dying include:

1. Electrical issues

All the electronics in your car get power from your car battery, including your stereo, dashboard, and lights.

Generally, the higher the number of components you are using on the battery when it’s on, the faster its lifespan is depleted.

When the charge is too low, the battery will not be able to run these components at full power.

2. Engine starts slowly

Your car battery will typically become less effective overtime due to wear, and as a result manifest weak car battery symptoms.

In particular, an old battery will take much longer to convert chemical energy to electrical energy that is necessary to start the engine. This is usually a sign of imminent failure.

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3. Bad odor from the battery

If you notice a bad smell when you open the hood, it may be an indication that your battery is in a bad condition.

A sour smell generally means that the battery is leaking gas, which can be caused by an internal short or damage to the battery. Get it checked out as soon as possible and replace it if necessary.

4. The check engine light is on

The check engine light signals that there is an engine-related problem with your vehicle. This could be caused by a malfunction in your car’s exhaust system, fuel, ignition, or even battery.

If you suspect that the battery may be the culprit, have a mechanic test it to see if it is working properly.

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5. Corroded terminals

The terminals are the positive and negative metal connectors on the top of your battery. If there is a white, ashy substance on these terminals, you may have a corrosion problem.

Corrosion can cause voltage issues and difficulty starting the vehicle, a telltale sign that the battery has a problem.

6. Battery is swollen

Swelling is usually a sign of an overcharged battery. Overcharging causes hydrogen gas and heat to build up on the inside, forcing the outer case to become warped and expanded.

A swollen battery is extremely dangerous, as it can explode anytime and cause serious damage to you or your car. In most cases, the best solution is to replace the swollen battery with a new one.

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How Much Voltage Does My Car Battery Need to Run Properly?

A fully charged car battery should generally measure 13.7 – 14.7 volts when the engine is running. This range may vary slightly depending on the specific conditions.

For instance, the battery current tends to drop when the atmospheric temperature falls, which can in turn lead to a slight reduction in the voltage.

If it falls below 11.5 volts, you need to charge the device as soon as possible. Using the battery in such a state can cause plate sulphation (buildup of lead sulphate crystals within the battery), which in turn diminishes its efficiency and duration of usage.

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How to Test Your Car Battery with Multimeter

You can easily test your car battery using a simple device known as a multimeter. A multimeter allows you to determine how much power is left in your battery by measuring its voltage.

Note that multimeters are ideally designed to test maintenance-free batteries, which do not have plastic caps on the cells.

If your battery has these caps, you should use a hydrometer instead of a multimeter. Here are the steps to test a car battery with multimeter:

Step 1

Let your battery stay at least one hour without usage before testing it. This is because the battery may hold on to some power from the alternator immediately after driving, which can result in a false reading.

Now turn the headlights on (without turning the car on) and wait for about two minutes to eliminate any surface charge on the battery.

Step 2

Inspect the battery for any signs of corrosion or build up on the terminals. If there are whitish or yellowish crusts around the metal connectors, they may interfere with the reading.

Use a battery terminal cleaner and a terminal brush to clean off the corrosion. Skip this step if there is no corrosion.

Step 3

Once you have prepared your battery, select voltage on the multimeter and set it to 15 to 20 volts DC (not AC). Note: Your lights should be turned off by now.

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Step 4

Touch the negative probe to the negative terminals of your battery, and the positive probe to the positive terminals. Multimeters and batteries are usually color coded to make this step easy: red = positive; black = negative.

Step 5

Check the readings on the multimeter. If the display shows 12.5 – 12.6 volts, the battery is fully charged. If the battery is 75 percent charged, expect about 12.58 volts on the multimeter. Anything below 12V means that the battery is out of charge.

Step 6

While holding the probes to the battery terminals, have someone else turn on the car as you observe the readings on the multimeter. The voltage should change now but if it goes below 10V, the battery is not producing enough power to run your car properly.

How to Test Your Car Battery without a Multimeter

If you don’t have a multimeter at hand, there are other ways you can test the voltage in your battery. Here is how to check if car battery is bad.

Step 1

Inspect the battery for any signs of leakage, corrosion, or swelling, which may warrant immediate replacement. If the battery looks fine, you may proceed to the next step.

Step 2

Turn the headlights on (without starting the engine), and leave them on for about fifteen minutes.

Step 3

Have someone crank the engine (with the headlights still on) as you observe how the lights react from the outside of the car. The bulbs should dim slightly as the car is powered on.

If they dim too much or turn off altogether, or you notice clicking noises from the engine, then your battery certainly has a problem. This is a sign that your battery is not generating enough power to start the car.

The quandary here is that you cannot use this method to get accurate voltage readings as we did with the multimeter, but it is still a great way to determine whether your car battery has enough charge to run your vehicle.

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Why Does My Car Battery Die So Quickly?

Some of the most common causes of a short lifespan in car batteries include extreme weather, overworking the alternator, charging problems, persistent electrical drains, and corroded or lose battery connections. How to know if car battery needs to be replaced:

a) Lose or corroded battery connections

If your battery connections are corroded, the charging system may not be able to top off your battery when driving. The same is true about loose battery connections.

b) Extreme weather

A new or stable battery may not be easily susceptible to extreme conditions, but an old or weak one may fail in hot or cold weather. Extreme temperatures can also amplify other underlying issues.

c) Charging problems

If your car battery seems to fail when you are driving, there may be an issue with your charging system. Worn tensioners and stretched or loose belts can keep an alternator from functioning.

d) Leaving the lights on

Leaving the lights on can easily drain your car battery. Even a dim dome light will use up all your battery power overnight.

Always ensure that all the lights are turned off before you leave the car, especially if you have a malfunctioning system that causes the lights to stay on after turning the car off.

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FAQs Concerning Car Battery Life

How long should my car battery last?

The average lifespan of a car battery is about 4 to 5 years, but it can be as short as 3 years in extreme conditions. Battery life can be affected by subjecting the battery to severe vibration, chronically undercharging it, or running it down frequently.

What type of battery should I buy as a replacement?

If your car battery dies or is on its last legs, you can replace it with an AGM battery or a conventional wet cell car battery. Make sure that the new battery has the same or higher CCA (Cold Cranking Amp) rating than the old one.

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Conclusion

Hopefully the information above will come in handy if you are wondering how to know when car battery is bad.

If your car battery keeps on dying, you may have some type of parasitic drain on your system. You can perform an easy test by disconnecting a battery cable and then checking for current flow.

If you are using a multimeter for this task, be sure to select the highest amperage setting possible to avoid blowing a fuse inside the meter.

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