Blog Car Care Advice Battery Light On: 7 Reasons Why And What To Do
Car Care Advice

Battery Light On: 7 Reasons Why And What To Do

Looking for a mechanic near you for maintenance or repair? AutoNation Mobile Service brings the shop to you. Get a free instant quote today.
Get a Quote

When you see the battery light on, it’s usually a sign that something’s not quite right with your car’s battery or its charging system.

But what turns the battery light on in the first place?

And is it safe to drive your car with that battery indicator light on?

In this article, we’ll answer those questions, cover the basics of how a vehicle’s battery system works and help you understand everything else about your car battery light.

This Article Contains:

Let’s jump right in.

7 Reasons Why Your Battery Light Is On

The battery warning light on your dashboard usually gets activated due to one or more of the following seven reasons:

Reason #1: Bad Battery

A car’s battery usually lasts between 3 to 5 years.

But, as your car battery ages, the electrodes inside it might break, or the electrolyte contained within the car’s battery may leak. As a result, the battery voltage (and battery power) generated will decrease. 

And with a dead battery, the battery voltage would just drop to zero.

When either of these happens, your dashboard battery light activates to warn you of a bad battery or dead battery.

Reason #2: Malfunctioning Alternator

An alternator is a component that charges your vehicle’s battery. 

If your vehicle’s alternator is malfunctioning, the vehicle battery may not receive sufficient voltage for proper charging, or it may get exposed to excessive voltage. 

In many cars, the optimal charging voltage is between 13.6 and 14.6 Volts. If your vehicle has a failing alternator (or faulty alternator), it’ll probably produce a voltage outside the optimal range. And this can negatively affect the proper functioning of your vehicle battery. 

As a result, the battery warning light can turn on to indicate that you’ve got a failing alternator, or worse, a wholly damaged alternator.

Reason #3: Broken Alternator Belt

An alternator belt (aka serpentine belt) uses the power generated by the engine crankshaft to:

However, with repeated working, this alternator belt or serpentine belt can develop cracks over time and finally break. When that occurs, your battery can’t be charged anymore with the broken alternator belt, and the battery warning light turns on.

Reason #4: Corroded Battery Terminal

Your battery terminal (or battery post) can undergo corrosion from exposure to the leaking electrolyte solution, vented hydrogen, atmospheric moisture, and so on. 

Additionally, heat generated from your engine can accelerate the corrosion of your battery post or battery terminal.

But how does that affect your car battery?

A corroded battery terminal or battery post is a poor conductor of electricity. And since your battery ultimately receives power through these terminals, poor electrical conductivity can result in a battery charging problem.

Consequently, the dashboard battery light can turn on to indicate this charging problem.

Reason #5: Faulty Battery Cable

Battery cables are responsible for delivering power from the battery to the rest of your vehicle. 

If a battery cable cracks or degrades, the flow of electricity may get interrupted. Moreover, if the battery cable isn’t snugly fit (not loose and not too tight) around the battery terminal, the recharging process may also be adversely affected.

When either of these scenarios happens, your battery dashboard warning light could turn on.

Reason #6: Wiring Issues

Your charging system and the electrical circuits that draw power from it involve lots of wiring.

When any of these wires break or get disconnected for some reason, you’d have trouble charging the battery or drawing power from it.

For example, say your vehicle’s ground strap or ground wire is damaged.

The ground wire completes the electrical circuits in your car and ensures that electricity flows the way it’s supposed to. If it’s damaged, your vehicle could encounter charging issues, and the electrical components could start acting up in different parts of your vehicle. 

As a result, your battery light may activate.

Reason #7: Accessory Overload

Many accessory components in your vehicle draw power from the alternator. This includes the subwoofers, auxiliary lighting gear, winches, and more.

However, the problem here is that the same alternator also charges the vehicle’s battery. And if too many accessories draw power from the alternator at once, it won’t be possible to charge your vehicle’s battery effectively.

When this persists, your battery’s energy levels may get depleted too much, resulting in a battery light activation.

Apart from these seven common causes, there can be other reasons why your dashboard warning light or charging system light is on, like a:

So far, we’ve covered why your battery warning light is on.

But what should you do when you see the battery light on?

What Should You Do If Your Battery Warning Light Is On?

If your vehicle’s battery light is on, it’s your cue to get the vehicle inspected ASAP.

For this, you can take your car to the dealership or an auto service shop. 

Better yet, you could request a mobile mechanic to come to you.

We recommend contacting a mobile mechanic since driving your vehicle to a dealership or auto repair shop with the battery light on isn’t safe or practical. 

A mobile mechanic can come to where you are and inspect your vehicle’s electrical system to check if you’ve got a bad alternator, charging problem, or so on. Additionally, the mechanic can tell you whether you’ll need a new battery or require repairs for other electrical components.

Either way, irrespective of whether you choose mobile mechanics or repair shops, just ensure that the professional mechanic you hire:

But where do you find such mechanics?

Just contact AutoNation Mobile Service — a convenient, accessible, and affordable mobile auto repair solution.

With AutoNation Mobile Service:

To book your repairs, all you have to do is fill in this online form, and we’ll take care of the rest!

Next, let’s look at some FAQs related to the dashboard battery light turning on:

3 FAQs About Battery Light Activation

Here are answers to the three most commonly asked questions related to car battery light activation:

1. How Does A Vehicle Battery Work?

A vehicle battery stores and converts chemical energy into electrical energy (electricity).

Usually, your car battery would contain a set of six electrochemical cells that generate a total of 12 Volts.

The vehicle’s battery powers the ignition system, air conditioner, interior lights, power windows, and more. Essentially, the battery brings to life the different electrical components in your vehicle!

But won’t the battery run out of juice from powering so many things?

Typically, it wouldn’t. 

And it has to do with how your vehicle’s battery system works:

In short, once the engine is fired up, the vehicle’s battery usually has the means to charge itself.

2. What Does The Battery Light Do?

Every time you start your car, the dashboard lights come on. This includes the check engine light, brake light, coolant warning light, power steering light, the battery dashboard warning light, etc.

And, in a few seconds, these lights would go off. 

However, if the car battery light (aka charging system light or battery indicator light) doesn’t turn off for some reason and stays on while you’re driving, you might have a problem on your hands. 

The battery light staying on is your vehicle’s way of indicating that there are issues with the:

3. Is It Safe To Drive With My Battery Light On?

While it could be possible to drive your car with the battery light on, we advise against it.


Chances are that your vehicle’s battery is running on whatever juice was left from the last battery recharge cycle. But there’s a high chance that the battery power will get drained entirely, and your engine may stop running.

Essentially, you might not be able to drive for very long with the battery indicator light on.

Moreover, if you turn off your engine, you may be unable to restart the ignition system without:

Closing Thoughts

There are many reasons why your battery light could turn on.

It could indicate a bad battery or dead battery, a charging problem, a faulty alternator, a wiring issue, and so on.

And while driving with the vehicle’s battery light on is possible, it’s not recommended. You won’t know when your car may just stop running or if you’ll be able to start your engine once it has been turned off.

If the vehicle battery light is on, the best course of action is to get in touch with a mobile mechanic.

For convenient, hassle-free repairs, you can simply contact AutoNation Mobile Service

Our certified and experienced technicians will come right to your driveway to diagnose and resolve any vehicle issues you may have!