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Why Is The Battery Light On?

You’ve started your vehicle, and suddenly, you notice that your battery light is on. What does it mean when the battery light comes on while driving? 

There are a few possible causes, but the bottom line is that your battery is likely failing. It’s very important to fix this problem before the battery fails completely. 

It’s very important to fix this problem before the battery fails completely.
It’s very important to fix this problem before the battery fails completely. 

What Is A Car Battery’s Purpose?

Most vehicles come equipped with a 12V battery, and this battery powers all of your car’s electrical components. That includes the radio, headlights, and brake lights

Most importantly, this 12V battery powers your ignition system. Without power, your ignition system won’t work, and your car won’t be able to start. 

Why Is The Battery Light On In My Car?

“My battery light is on. Why?”

If your battery light stays on once you’ve started your car, there are a couple of possible causes. So how, exactly, does the battery light work, and why is it on? There a few possible causes. Remember, the battery light doesn’t necessarily indicate a problem with the battery itself and you need to check battery light.

In fact, you’ll sometimes see your battery light on in car after replacing your battery. An illuminated battery symbol on your dash could be due to your vehicle’s alternator, and it may light up due to issues occurring within the battery itself. It can also indicate a simple connection issue. 

Battery Light On: Check Alternator 

Basically, your alternator charges your vehicle’s battery. There’s a circuit in your vehicle that detects the amount of current being provided to your battery. If the current isn’t strong enough, it warns you with this battery light. 

If you’ve encountered the battery light, it might just be that your alternator belt is broken. Luckily, the alternator belt is a relatively inexpensive and easy fix. However, it could also be that your alternator has failed entirely. Fixing this problem will be more complicated and more expensive. 

 the alternator belt is a relatively inexpensive and easy fix
The alternator belt is a relatively inexpensive and easy fix

Battery Light On: Replace Battery

Alternatively, you might be seeing this battery light due to a problem with the battery itself. Batteries, like all electronic components, have a lifespan. 

Eventually, you’ll need to replace your battery. However, early warning signs such as slow cranking will typically begin to occur long before your battery light turns on. 

If you’re not sure whether to replace your battery or alternator, keep reading. We’re about to go over a simple test that you can use to determine why your battery light’s on. 

Battery Light On: Is It My Alternator Or My Battery?

Is It My Alternator Or My Battery?
Is It My Alternator Or My Battery?

If you’re not sure whether the problem lies with your alternator or your battery, the most obvious solution is a mechanic. However, there are some DIYers out there that won’t be satisfied with that answer.

Let’s briefly go over how you can perform a simple at-home test to determine the cause of your dash’s illuminated battery symbol. Before you can begin this test, you’ll need a battery tester. 

First, connect your battery tester to your vehicle’s battery. For this initial battery test, your vehicle shouldn’t be running. If your battery’s voltage is close to what it should be, the cause of the battery light is likely the alternator. Still, we don’t want to leave anything to chance. 

To check your alternator’s health, keep your battery tester connected to your vehicle’s battery. Start your engine and rev it up to 2,000 RPM. Ideally, your battery’s voltage will increase as your engine warms up. If the voltage stays the same or drops, there’s a problem with your alternator. 

Performing this test should give you a good idea of the cause of your battery light. There are a few other miscellaneous causes that may be causing your battery light to turn on. If you’ve performed this test with no luck, check for these common issues.

Other Causes

If you’ve checked your alternator and battery but your battery light is still on, there are a few other things you should check. Luckily, these alternative causes are easy and inexpensive to resolve. 

Check the connection around your battery. If they’re loose, tighten them up. It could be that your battery isn’t capable of providing the correct current due to this loose connection. If you find your battery light on after replacing the battery, it’s likely due to a loose or faulty connection. 

Another common issue is rust. If your connections have gotten rusty, the rust could be causing connectivity issues. 

If this is the problem, you can eliminate the rust with nothing but a toothbrush and a simple homemade concoction. Mix one tablespoon of baking soda with one cup of water. Then, get to scrubbing! Reconnect your newly rust-free battery. Hopefully, the issue has been resolved. 

Battery Light On: Preventative Measures

You’ve just resolved your battery light issue. You’re probably wondering how you can save yourself the time in the future. Luckily, there are preventative measures that you can take. These preventative measures will decrease the likelihood of future battery issues. 

Keep your battery tightly fastened. A loosely fastened battery will move around when you drive, which can damage the battery and loosen connections over time.

Turn off all of your lights when your engine isn’t running. Using your lights and radio for short periods of time with the engine off is fine. However, doing so for too long can drain your battery. 

If you drain your battery, you can simply jump it off with some jumper cables. However, making a habit of this will decrease your battery’s lifespan. Avoid draining your battery at all costs.

Additionally, you should keep an eye on your battery. Clean it often to prevent corrosion and make sure that your battery and all of its connections are tight. 


As you can see, an illuminated battery symbol on your dash can mean a variety of different things. If you see your battery light on, remember that the problem might not be the battery itself. It could just as well be your alternator or even a connection problem with your wires. 

Here, we’ve listed the possible causes and a few tests that you can perform to determine the cause of your battery light. Hopefully, the tips and information on this page will help you resolve your battery light problems with ease. 

Read more: Why Does My Oil light Come On? How to reset it?

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