How Long Can You Drive With Battery Light On? [Causes and What to Do]

It can be worrying if the battery light turns on when driving. Has it come on while you are behind the wheel or when you start your car in the morning?

The reasons for the battery light to come on vary, but how long can you drive with it? This depends on what caused it.

If you are asking how long can you drive with the battery light on, here’s a suitable response for you. If the alternator or the charging system is faulty, you have about 30-60 minutes to drive your car. That means your accessories and vital engine functions will use the reserve power in the battery.

But if the charging system is okay and the battery is the culprit, you can drive your car with the battery light on as long as you don’t stop the engine. The alternator will continue generating electric power for accessories and other systems, but the engine can also stall unexpectedly.

Read on for all possible causes of the battery light coming on. This article also covers the diagnosis and cost of fixing this problem. Let’s dive in!  

What Does the Battery Light Mean?

The battery light is a red dashboard indicator, which comes on if there is a fault with the battery or the charging system. A car battery can be dead or too weak to hold an electrical charge, or the alternator does not generate enough electrical power to charge it.

In other words, the battery light comes on when the battery voltage drops below the minimum level. You need to take your car to a mechanic for diagnosis to find the cause of the problem and fix it immediately.

The battery light on the dashboard tells you the car will stall soon and may turn into a piece of junk metal. It can leave you frustrated by the roadside or in the middle of nowhere.

When the battery runs down, the engine won’t start. You will need to recharge the battery or replace it if it is damaged.

How Long Can You Drive with Battery Light On?

Seeing the battery light illuminating your dashboard when driving does not mean you pull over immediately. You have about 30-60 minutes to drive if the charging system is the problem. But that depends on the lifespan and health status of the car battery,

But if your alternator or other charging system components are faulty, you can drive your car for many more hours. However, you should not stop the engine because it won’t start again due to a dead battery. The engine can also stall unexpectedly.

In general, the time you can drive your car depends on the status of the battery and what caused the battery light to turn on. Drive straight to the nearby auto repair shop for diagnosis and fixing.

Causes of Battery Light Turning On

The causes of the battery dashboard light turning on are many, and they can vary from car make and model to the next. But in general, the following are the most common causes:

1. Weak or Dead Battery

Car batteries have a definite lifecycle. The battery cells wear out with every charging and discharging cycle, and finally may die. It can also be caused by broken plates or leaking battery acid.

Dead battery cells mean your car battery won’t take in or store the electrical charges. That means the terminal voltage will be lower than the expected minimum, which triggers the battery management system to signal the control module to turn on the battery light.

But how do you know your car battery is nearing its service life or is becoming weak? Check out the following signs:

• Dim headlights
• Slow cranking or the engine taking too long to start
• Clicking sound when turning the initiation key
• Electrical accessories malfunctioning
• The engine doesn’t start
• Engine backfires
• Swollen battery case
• Jumpstarting becomes more frequent
• The smell of sulfur/battery acid leakage

But before concluding the batter is the culprit, test it first. Use a digital multimeter to measure the voltage across the battery terminals.

If the battery is dead, the voltage will read almost zero. But if it is weak, the reading will be below 12.5V. The recommended voltage for a healthy car battery is 12.6V or more when the engine is not running.  

2. Faulty Alternator

A car alternator is an electric power generator. It is driven directly by the engine to generate power for charging the battery. It is a vital component of the charging system.

An alternator can have electrical shorts or open in its windings, which interferes with its output voltage. The alternator output voltage is about 13.6V – 14.6V. Anything below the range will cause the battery light to turn on.

Like the failing battery, a failing alternator also shows signs. Some of these overlap with those of a dead or weak battery. But typically, you will experience the following:

• Frequent engine stalls
• Growling or whining noise from the engine bay
• Flickering lights
• Dim or overly bright headlights
• Dead battery
• The smell of burning rubber or wires
• Slow or malfunctioning accessories
• Difficulty starting the engine

Take your car for checking. A technician conducts an extensive test on the alternator and advice whether it is repairable or should be replaced.

3. Broken Serpentine Belt

The alternator is coupled to the engine’s crankshaft with a serpentine belt. A slacken serpentine belt will cause slips, meaning the alternator will not spin at the engine speed. That result in lower voltage output.

A broken serpentine belt means the alternator cannot run. So, there is a zero-output voltage at the alternator terminals.

Visually inspect the serpentine belt for any damages and replace it if necessary.

4. Damaged or Corroded Ground Strap

The ground strap is the cable from the negative terminal from the battery to the car chassis.

A damaged or corroded ground strap creates an open circuit. Therefore, the current does not flow back to the battery. This problem manifests itself in malfunctioning electrical accessories and battery lights coming on.

5. Loose or Corroded Battery Terminals

Like ground straps, corroded or lose battery terminals disrupt the flow of electrical power from the battery. That will create an open circuit, interpreted as weak battery voltage. The car’s computer may think the battery is dead.

6. Faulty Wiring of the Charging System

A car’s charging system is complex, with many wirings connecting the alternator to the battery through the battery management system. These wires can stiffen and break over time due to exposure to harsh conditions.

Broken wires create an open circuit that disrupts the charging system. The battery will not be recharged, and its voltage drops below the minimum after some time.

7. Blown Fuse

Your battery and the alternator or charging system may be linked by a fuse. If that fuse blows out, the battery won’t recharge, which triggers the battery light.

8. Faulty Battery Sensor

The battery management system relies on the information from its sensor. The sensor measures the current from the battery and monitors the terminal voltage. It also checks the state of the charge and the battery’s health.

The battery management system or body control module uses data from the battery sensor to adjust charging voltage and other parameters to enhance fuel efficiency and the battery’s lifespan.

A faulty battery sensor gives data outside the specified range, which triggers the battery light.

9. Accessories Overload  

Having many accessories in the vehicle running can draw excess power from the battery. The alternator may also not keep up with the increased demand for electrical power.

This usually happens in the winter when you are likely to turn on AC, seat heaters, and other accessories. Also, the aftermarket accessories, such as a more powerful audio amplifier and speaker, can cause accessories overload.

What Can You Do If the Battery Light Illuminates the Dashboard?

The best action is to drive straight to the nearest auto repair shop to have the problem checked. You don’t know how long you can drive your car with the battery light on. It is estimated to be about 30-60 minutes, but it can be far less than that if your battery is nearing its end.

Alternatively, you can request a mobile mechanic to come to your location. It is unsafe to continue driving your car with the battery light on.

Diagnosis and Resetting the Battery Light

The diagnosis of battery light involves checking the possible causes explained above to find the culprit. You better take your car to a dealership or an auto repair shop. But if you are a DIYer, you can try out the following:

1. Turn off all accessories, including radio, AC, heated seats, etc. If they are the cause, your battery will charge, and the dashboard light should disappear after a few minutes.
2. Check the alternator output voltage when the engine is still running. It is the culprit if the voltage is below the minimum of 13.6V. You will need a professional for further diagnosis.
3. Measure the battery terminal voltage when the engine is still running. The voltage reading should be about 14.0V, a slightly low or higher voltage is still acceptable.
4. Turn off the engine and measure the voltage again. It should read 12.6V or more for a healthy battery. If you get lower, the battery is weak or dead and should be replaced.
5. Inspect the ground strap and serpentine belt and replace any component with physical damage.
6. Clean the corroded battery terminals to reduce resistance to current flow.
7. Check the charging system wiring for open or short circuits. You may need to call a technician for this if you are not experienced with the wiring system in your car.
8. Clean the battery sensor if dirty or replace it if faulty. It is often installed on the negative battery terminal but can also be on the positive side in some cars.

If nothing works after the above diagnosis, call a mechanic. The professional should help you diagnose and reset the battery light.

Cost of Fixing Battery Light

The cost varies, depending on the part to be replaced or repaired. It also depends on your location and the make and model of your car.

Generally, the battery light inspection or diagnosis fee can range from $50 to $150. The cost of replacing various parts is outlined in the table below. But remember, these estimated figures can change over time!

FAQs

How do you tell if it’s a dead battery or a bad alternator?

A faulty alternator and a dead battery have some overlapping signs. But you can still distinguish the two if only one is affected. Your car will not start with a dead battery, and a weak one will cause the engine to take longer before starting.

But if the car stalls when driving or the engine suddenly turns off, the alternator is the culprit.

Why does my car operate with the battery light on?

Your car can continue to run normally with a battery light on because of the reserve power in the battery or an alternator still running. An alternator can still generate enough power for electrical systems, even if the battery is weak or dead.

How long does a car battery last?

A car battery has a lifespan of about 3-5 years, but that depends on many factors. The battery cells wear out over time with every charging and discharging cycle, which is why car batteries have a definite lifespan.

How to reset the battery light on Ford F150

You can reset the battery light in Ford F150 by disconnecting the negative battery cable. Next, turn on the headlight switch for 30 seconds and reconnect the battery cable.

Why is my brake and battery light on?

The two dashboard lights can come on to indicate a problem with the charging system. It usually means your alternator is faulty or dead, the voltage regulator malfunctioned, or broken or loose wiring connections.

Can a fuse cause the battery light to come on?

Yes. If a fuse connects the charging system and the battery, it can cause the battery light to come on if it is blown out. That is because it creates an open circuit, preventing the battery from charging when the alternator is running.

Does the check engine light come on for the battery?

Yes, but not always. A dead or weak battery will turn on the battery light on the dashboard. But low voltages can cause your car’s computer to malfunction, triggering the check engine light. It is possible but rarely happens.

How can you prolong the life of your car battery?

Proper car battery maintenance and practice can prolong its service life. Consider doing the following:

• Test and charge the battery when necessary
• Clean the battery terminals regularly
• Don’t over-drain your car battery. Don’t use the accessories when the engine is not running
• Drive more frequently to keep the battery charged
• Avoid driving short trips
• Minimize exposure to heat
• Tightly fit your car battery

Can you start a car without a car battery?

No. You cannot start a car without a battery since the starter motor needs electrical power to crank the engine. But you can use an alternative electrical power source. It should supply the correct voltage and current.

Is it the battery or is it a dead alternator?

A car with a dead battery usually would not start up or have problems starting up. If your car’s battery is dead, it might also mean that you would have dimmer headlights or a broken sound system. 

On the other hand, when you have a broken alternator, it could have the effect of stalling while driving or shutting your engine off altogether.

Is it safe to drive with my battery lights on?

No. It is unethical and unsafe to drive with your battery lights on. 

It’s bad because the main reason why your car has battery lights is that it warns you whenever your vehicle’s battery, or the other linked parts, is broken. 

When you find your car battery lights on your dashboard, find out what is causing it and fix the problem. If you ignore it, you may lose out on battery charge. 

Losing out on battery charge would mean that there would be difficulty when restarting your car.

So, if your car battery lights are flickering on and off, it would be less of a bother to check it and fix it rather than break it down.

Final Remarks

Driving with the car battery light turned on is dangerous, even if you have an estimated 30-60 minutes before the car dies. When the light appears, visit the nearest dealership or an auto repair shop for diagnosis and the issue to be solved.

Different reasons can cause a car battery light to come on, including a dead battery, faulty alternator, broken serpentine belt, accessories overload, and many others. Regardless of the cost, fix the problem immediately.

Troubleshooting and resetting the battery light is straightforward and relatively affordable. You should pick up your car the day you drop it at the dealership.