Charging System Warning Light – Causes & Fix

The dashboard display in your car is crucial to your understanding of the health of your car and to alert you to issues that might not be obvious to you yet.

Among the helpful early warning signs your dash can alert you to is the charging system warning light. But when we first see this light, it might be difficult to diagnose exactly what it is this light is warning us of.

Battery failure is the number one cause of breakdown call-outs in the UK, especially in the winter, so it’s wise to be aware of what it’s trying to tell you.

In this article, we’re going to discuss what the charging system light means and why it might have turned on, as well as how to fix and reset it.

What Is a Charging System Warning Light?

Before we discuss what the charging system warning light means, it’s good to understand what the charging system in your car is.

The charging system consists of three parts: a battery, an alternator, and a voltage regulator. These components work together to power all the electrical components of your car, taking the pressure off your engine.

The alternator passes energy to the systems that need electrical power while maintaining the charge in your car battery.

With that in mind, it’s easier to understand that a charging system warning light alerts us when the current in your car’s electrical system is operating at below optimum levels.

Battery light symbols

If the battery light symbol on your dash is green or not on at all, then your car battery is being charged effectively.

If it turns yellow, it means the battery has a low charge. This is not so serious and can just appear after short drives.

However, if the light turns red, it means that the battery is no longer recharging due to a fault and requires immediate attention.

What Does Charging System Warning Light Mean?

If your battery is no longer receiving a charge from your car’s charging system, then this can trigger the warning light.

In short, the practical meaning of this light is that the battery of your vehicle is only running on its stored charge to power its electrical system.

What Causes the Battery Light to Come On?

When your car’s charging system light activates, it means the charging system has failed, and the battery is no longer receiving a fresh supply of electricity from the alternator and the voltage regulator.

While the overall meaning of a charging system warning light indicates a low charge or a lack of one, the initial reason the light turns could be one of many.

Loose battery cable

Loose battery cables can lead to a poor exchange of power between the alternator and the battery.

The cables should be wound tight, and you shouldn’t be able to move them by hand. If you doubt the tightness of the connection, try tightening them with a wrench or pliers but be careful not to 0vertighten as this can strip the bolts.

Corroded battery terminals

The battery terminals are designed to be good conductors of electricity, but like any electrical component, as they are used, they can develop wear and become corroded.

Corrosion on the terminals is a white, green, or blue substance that occurs with regular use and is worsened by persistent heat. It is acidic and will eat away at the terminals, so use a stiff brush and baking soda/water solution to clean them but use caution to avoid skin irritation with the correct PPE.

Malfunctioning alternator

The alternator takes energy from the crankshaft and changes it into electricity which is then stored in your battery. Alternator issues can take time or happen suddenly, but once they do, they can cause a variety of issues in your car’s electrical components.

A voltage regulator limits energy output to 14.5 volts, and if that is failing to do its job, that can also be the source of the problem.

Keep a lookout for dimming headlights, which is often an early sign of a bad alternator.

Bad battery

Conventional car batteries have a lead dioxide and lead plate submerged in a sulfuric acid electrolyte solution in each of its six cells. A normal 12-volt battery has a 3-5 year lifespan, and over this period, the plates can break, or the solution can leak, resulting in a dead battery that will need replacing.

Wiring issues

Faulty wiring can prevent your battery from holding a charge, causing the energy to drain from it quickly. Wiring that was installed well initially can loosen or malfunction over time and will require a mechanic’s inspection if it fails.

What Happens When the Charging System Light Is On?

When this light is on, it means your car’s charging system has been compromised and that your car battery is running solely on the electricity it has stored.

While your charging system light doesn’t mean anything immediately, it does mean that your car is running on limited energy, and the battery may be at risk of dying at any point.

How to Fix and Reset Check Charging System Light

You might want to do a reset of your charging system light to check that it isn’t on incorrectly. This can be done in a variety of ways.

However you choose to check the system, it is important to be safe if you decide on your car’s electrical and charging system. Wear rubber gloves to avoid shock and goggles to protect your eyes from acid splashback.

What you need

Most methods can be performed with minimal gear besides PPE, but our method will require an OBD2 scanner, which is a diagnostic tool that scans the electrical components of your car.

Step 1

If your check engine light is on, connect your OBD2 to the port usually located under the steering portion with its 16 pin plug.

Step 2

Turn the ignition on and wait for the scanner to initialize.

Step 3

When the scanner is ready, you will need to key in the relevant data. This will include the type, model, and make of the car engine and VIN.

Then begin the scan of your car’s diagnostic system. Some scanners have a single button to initiate the scan, and others will require you to go through a manual.

Step 4

After the OBD2 has completed the scan, it will give you one or several problem codes. Record them and transfer them to your computer using a USB, or Bluetooth if you have the capability.

Step 5

Use these codes to check in the manual exactly what it is that is causing your car to suffer. The manual may only show basic codes, but more advanced ones can be found in supplemental sections online.

Is It Safe to Drive with a Charging System Warning Light?

The charging light means that your car is running on a limited supply of energy, so driving while it’s on could leave you stranded at any time.

So while it might not be strictly unsafe, it’s unwise to drive when the charging system light is on as your car could stop from a dead battery at any time.

How Long Can You Drive with the Battery Light On?

This depends upon exactly what it is that has caused the light to switch on.

Assuming the issue is with the alternator, then your car will have around 30-60 minutes of life left before it dies.

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Author: Dave Johnston

Dave Junior is a hands-on automotive technician with experience in performing service, diagnostics, and repairs on domestic and imported vehicles. He enjoys writing and sharing his knowledge far and wide.

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