Skip the auto shop - Our mechanics make house calls

How to React If Your Battery Light is On

close up of battery light coming on

The battery light or charging warning light, available on the dashboard of your car, indicates malfunctioning or poor charging of the battery. This light illuminates whenever the charging system does not charge the battery with a voltage above approximately 13.5 volts. As this warning may be triggered by a number of things, it is important to take steps to ensure that you know what the actual issue is before replacing any parts.

  • Note: This article describes a general check of most common car battery vehicle charging systems and some vehicles may be tested differently.

The troubleshooting process can be fairly straightforward, but there are certain issues that only a professional should address. If the problem appears to be complex, or if the process of troubleshooting becomes daunting, call a mechanic to come and perform an inspection.

Here’s what you can do when your car’s battery light turns on:

Part 1 of 3: React to the battery light

When you first turn on your car with the engine off, the battery light will illuminate and this is normal. If the battery light comes on while the engine is running and the vehicle is being driven, this indicates a problem with the charging system.

Step 1: Turn off everything that draws power. If the battery light is on, then there is still enough battery left to power the vehicle but possibly not for very long.

When this happens, first turn off anything that draws power from the battery, except for the headlights, if you are driving at night. This includes the air conditioning and heating system, the stereo, any interior lights, and any accessories such as heated seats or heated mirrors. Disconnect any phone or accessory chargers as well.

vehicle parked with ignition on

Step 2: Stop the car. If you notice the engine temperature getting warmer or it is is overheating, stop the vehicle on the side of the road to prevent the engine from damage.

If you notice a loss in the power steering, then your car may have a broken a serpentine belt and the power steering or the water pump and alternator may not be turning.

  • Tip: Try starting your car in a safe location, if the battery light comes on again, do not drive it. Shut off the engine and open the hood to see whether the serpentine belt, alternator or battery have any problems that can be identified visually.

  • Tip: Always turn off the engine before inspecting the battery or other components.

Part 2 of 3: Inspect the Battery, Alternator, Serpentine Belt and Fuses

engine battery location

Step 1: Locate the battery, the fuse box and the alternator. Locate the battery, the fuse box behind the battery, and the alternator at the front of the engine.

In most vehicles, the battery is located under the hood. If the battery is not under the hood, then it is either located in the trunk or beneath the rear seats.

  • Warning: Always use safety glasses or goggles and gloves while working on or near a car’s battery. Follow all safety precautions when handling batteries.

good battery vs bad battery reading

Step 2: Inspect the battery. Look for corrosion on the battery terminals and any damage to the battery.

  • Warning: If the battery is damaged or shows signs of leaking, it may need to tested by a professional mechanic and replaced.

corroded battery terminal

Step 3: Remove corrosion from the battery terminals. If there is a lot of corrosion on the terminals, use an old toothbrush to scrub it and remove the corrosion.

You can also dip the brush in water to clean the battery.

  • Tip: Mix 1 tablespoon of baking soda with 1 cup of very hot water. Dip an old toothbrush into the mixture and scrub the top of the battery and at the terminals where corrosion has accumulated.

Excessive corrosion at the battery terminals can cause a low voltage condition which makes the starter turn slowly when trying to turn on your vehicle, but it will not illuminate the battery light if the alternator is charging properly once the car is started.

person inspecting terminals

Step 4: Secure the clamps on to the battery terminals. Once the terminals are cleaned, make sure that the clamps connecting the battery cables onto the terminals are secure.

  • Tip: If the clamps are loose, use a wrench or a pair of pliers, if available, to tighten the bolt on the side.

close up of cables and clamps

Step 5: Inspect the battery cables. Inspect the battery cables that deliver power from the battery to the vehicle.

If these are in poor condition, the vehicle may be receiving insufficient power to start the vehicle properly .

Step 6: Inspect the alternator belt and alternator for problems. The alternator is located on the front of the engine and is driven by a belt.

alternator belt replacement

On some vehicles, this belt is easy to spot. On others, it can be nearly impossible without removing engine covers or accessing them from underneath the vehicle.

  • Tip: If the engine is horizontally mounted, the belt will be on either the right or left side of the engine bay.

Inspect the electrical connections on the alternator to make sure they are secure and tight.

Step 7: Check the condition of the serpentine belt. Verify that the serpentine belt is not missing or loose.

good vs bad belt

Look for any damage or fraying on the belt.If the alternator belt is damaged, it needs to be replaced by a qualified mechanic.

  • Tip: If the belt is the culprit, it is likely that there would also be other symptoms like a squealing noise emanating from the engine.

Step 8: Check the fuses.

fuse box locations

The fuse box will be located either under the hood or in the car’s interior.

If the fuse box is inside the car, it will be either on the ceiling of the glove compartment or located on the left side of the dashboard near the floor of the driver’s side.

  • Tip: Some vehicles have fuse boxes inside the vehicle and under the hood. Check all the fuses in both boxes for any blown fuses.

Step 9: Replace any blown fuses. Some cars will have extra fuses in the fuse box for some of the smaller fuses.

If any of the large fuses are blown, then the system may have a major short and should be checked and replaced by a certified mechanic.

Part 3 of 3: Test the Battery

Step 1: Start the engine. After all of these steps have been taken, the engine needs to be started up again to see if the charging warning light is still on.

If the light goes out after starting the engine, check the charging system for any other problems.

If none of the steps taken do anything to fix the problem, then the problem is probably due to a malfunctioning alternator. This is something that needs to be tested and repaired by a professional. Call in a certified mechanic, like one from YourMechanic, to inspect and repair the battery and alternator systems.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...

Related questions

Q: Battery dead car won't run

Disconnecting the battery while the car is running to check the charging system may have been ok in older cars, however most newer cars with all the on-board electronics do not respond well to that old trick. Things like...

Q: What should I know about the system warnings displayed in the message center?

Your car’s message center not only lets you change settings and check various systems and their operations, but it can give you a number of different warnings. However, there are a few things that you’ll need to know here: ...

Q: my battery light is on when the car was started, in the morning whiles going to work it was normal, it was till I closed from work

Hey there. I would test your alternator. Use a multi meter to ensure your alternator is reading 13.8-14.2 volts while the vehicle is running. If it is not, try replacing the alternator and see if it removes the battery light....